How to Use Your DSLR Features and Exposure Settings to Improve Your Photography
Whether you’ve been shooting for awhile, or you’re completely new to photography, you should have a good handle on everything discussed in this guide to DSLR photography if you want to get the most out of your camera. I hope that you’ll find this a useful and comprehensive reference.
This DSLR photography guide covers many interrelated topics. I’ve provided a table of contents to make it easier for you jump to the parts you’re most interested in.
1. DSLR Camera Features and Components
Here is a list of several basic DSLR camera components:
Camera Body
When we use the term, “camera body,” we’re referring to the camera only; not the lens, external flash, battery, memory card, or other attachments and accessories (see Figure 1.1).
Lens
The lens is attached to the camera body via the lens mount on the front of the DSLR. The camera and lens must have compatible interfaces or some form of adapter in order to make a proper connection. The lens release button must be pressed in order to detach the lens from the camera. The lens may have a switch which allows you to choose manual or autofocus functionality. Lenses are available in a wide selection of focal lengths (e.g. wide angle, normal, telephoto) that are suitable for different types of photography. Zoom lenses offer the flexibility of changing focal lengths without changing the lens. Fixed focal length lenses (often called, “prime” lenses) don’t allow you to zoom, but often have advantages over zoom lenses, including better optical quality. Photographers often regard their camera lenses as more crucial to the quality of their images than their camera bodies. Well-made and cared-for lenses tend to retain their value over the years.
Shutter Release Button
This is the button you press to take a photo. The shutter must be released in order to expose the image sensor to light from the scene. It is usually located on the top of the camera in a position accessible to the right-hand index finger. The default behavior of the shutter button on many DSLRs causes it to activate exposure metering and auto-focus as it’s partially depressed; releasing the shutter as it’s fully depressed.
Built-in (Pop-up) Flash
If your camera has a built-in flash, it can be activated automatically in Full Auto mode, or manually as needed, via a button. Built-in flashes are not as powerful as external shoe-mount flash units but they can come in handy for snapshots. On some cameras, the built-in flash can also facilitate wireless communication between the camera (acting as master controller) and one or more remote/slave flash units.
Viewfinder
Unlike with compact cameras, where you compose your shots by looking at the back of the camera (LCD screen), on the DSLR, you’ll usually look through the eyepiece of the viewfinder for composing, focusing, and viewing certain information provided by the camera (see Figure 1.2). Some DSLRs will allow you to use their LCD monitors the same way you would with a compact camera, but you won’t usually take photos this way.
LCD Monitor
One of the biggest advantages of your DSLR is its ability to preview an image immediately after you take a picture. The LCD monitor is located on the back of the camera and may have a swivel capability so that you can orient the screen for easier view from different camera positions. As you take each shot, a preview of the image will appear for a short time on the LCD. This monitor also gives you access to image data and the camera’s menu system.
Depth-of-Field Preview
When you’d like to get an idea of how much of your image will be in focus, based on your current aperture setting (f-stop), you can activate the depth-of-field (DOF) preview. This is usually accomplished by holding down the DOF preview button on the body of the camera as shown in Figure 1.3. Looking through the viewfinder, upon pressing the DOF preview button, you’ll notice that it gets darker with smaller aperture settings. This is because smaller apertures allow in less light, but this is not necessarily going to make your photo appear darker because other controls (e.g. ISO and shutter speed) can compensate for the decrease in light caused by smaller apertures.
Connection Terminals
Your camera may have terminals and jacks for a flash sync cord, microphone, USB connection, and A/V connections. See the documentation for your camera model to see what types of connections are available.
Settings/Controls
Knobs, dials, buttons, switches, and the menu system all give you access to numerous camera settings and controls. Many of the physical controls on the camera body can be customized to your preferences. Some of the settings and controls will, at times, be automatically handled by the camera. Other times, you will maintain full or partial control over them. The number of in-menu and on-camera settings might seem overwhelming at first, but keep in mind that you’ll deal with a very limited number of them on a regular basis.
Mirror
With many compact cameras and DSLRs, you can compose your shot before you take a photo by looking at a live optical view of the scene as your camera sees it. Most DSLRs have viewfinders that make shooting, focusing and controlling other features more convenient. The mirror located at an angled position in the camera body, just in front of the shutter mechanism, reflects the scene coming in through the lens, up to the viewfinder. Some “mirrorless” cameras operate differently and the viewfinder actually provides an electronic (rather than optical) view of the scene through the lens. Mirrorless cameras are not DSLRs.
Shutter
The shutter (or shutter mechanism) is a precisely timed and controlled sliding “window” that opens when you take a photo. It is located behind the mirror and in front of the image sensor. When the shutter button is pressed, the mirror moves out of the way and the shutter opens for a set amount of time (usually a fraction of a second) to expose the image sensor to the light coming in through the lens. The amount of time the shutter is open is determined by an important control called the “shutter speed” setting.
Image Sensor
The image sensor is a component located inside the camera body, just behind the mirror and shutter mechanism. When the shutter button is pressed the mirror and shutter open to expose the sensor to the scene. The sensor collects the light as small points of data (pixels) in order to record an image file. This image file is then stored on a memory card which you’ve previously inserted into your camera. Image sensors come in varying sizes and pixel densities. Full-frame sensors have an area roughly the size of a single frame produced by a 35mm film camera. Because of their size, they can capture a large area of the projected scene coming through the lens. So-called “crop” sensors are smaller, consequently recording a smaller area of the total projected scene.
Tripod Socket
Located on the bottom of the camera (see Figure 1.4), this threaded socket allows you to connect a tripod, battery grip, or other gear or accessories to your camera.
Battery Chamber
A door on the camera opens up to allow you to insert or remove the camera battery.
Memory Card Slot
One or more slots located on the camera body, as shown in Figure 1.5, that allow you to insert or remove the memory cards that are used to store the image files created when you take photos. Make sure you only attempt to insert the memory card type(s) compatible with your camera. Memory cards can be removed from the camera and then inserted into a memory card reader in order to upload the image files to your computer for organizing and/or editing. Since they are reusable, you can delete the images from the card via the delete or format feature on your DSLR opening up space on the card for new photos.
Hot Shoe
An external flash unit as well as some types of flash adapters, cords, and triggers can be attached to the camera’s hot shoe (see Figure 1.6). The hot shoe, located on the top of the camera, has contacts that match up to flash units compatible with the manufacturer’s camera/flash system.
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2. DSLR Shooting Modes
Your DSLR is capable of making complex exposure decisions for you. As a matter of fact, there is some highly sophisticated, computerized programming that goes into many of the shooting modes. Some of these modes take most, or all, of the guesswork out of taking pictures. Essentially, your DSLR can even function as a point-and-shoot, with the benefit of creating better quality images than you’d get with a smaller, compact camera. As you get more confident with your camera, you’ll want to graduate to more sophisticated shooting modes. But we’ll start here by addressing the basic, so-called “fool-proof,” modes.
Just to give you some context, shooting modes are what you use to tell your camera how you’re planning to use it. There’s no way we can cover all of the specific modes and terminology used by all of the different camera manufacturers, across all the models of cameras out there. But, generally speaking, a shooting mode sets up the way your camera will function in terms of handling exposure settings.
Fully Automatic Mode
More than likely, your camera has an all-encompassing automatic mode. On Canon and Nikon cameras this full-auto mode is denoted by a green icon on the mode dial. On your camera it might be under a different icon, or simply under the word AUTO. You can think of full-auto as sort of a point-and-shoot mode. Few camera settings are set by you, and the actual decisions about exposure are made entirely by the camera. ISO, aperture, and shutter speed are determined based on what the camera’s programming thinks is best for the scene. While this might seem like a great way to shoot, it provides you with very few creative choices and not always the intended results.
To use this mode, just set your camera to AUTO or the green icon, and you can start shooting just as if you were using a point-and-shoot. The camera will make all of the important exposure decisions for you including whether or not to trigger the internal or pop-up flash if your camera has one.
Again, just as with all of the automatic and easy shooting modes, you’ll have limited creative control over your exposure settings and the camera will not always make the best decisions on your behalf. That’s definitely a point you should be aware of. If you want more control, you’ll have to abandon these modes and move on to the ones that put more control in YOUR hands. We’ll discuss other modes as we progress.
Basic/Scene Modes
Now, besides full-auto, some cameras also have modes designed for very specific shooting scenarios like “Portrait” or “Landscape” shots, night shooting, action and other situations. Depending on the camera manufacturer, these might be called BASIC or SCENE shooting modes on your camera. These are more than likely found on consumer and some pro-sumer models than on high-end DSLRs. As you might expect, if you want the camera to attempt to make good exposure decisions for you, you’d select the BASIC or SCENE mode that matches up to your shooting scenario. I’ll stress this one last time: the camera’s not always going to make the best choices, and your creative options might be very limited, but these modes could make shooting a little easier for beginners.
Program or Program Shift (P) Mode
Program mode is another easy-to-use mode that gives the camera initial control over the aperture and shutter speed settings. The camera controls the balance between the aperture and shutter speed, but it allows you to shift the exposure mix in case you’d like to see one of the other settings in a different place.
For example, let’s say your camera is showing an aperture at f/5.6 and shutter speed at 1/60 sec. If you’d like to open up your aperture to f/4, you can turn a dial until you see that adjustment as your camera automatically makes the reciprocal adjustment to the shutter speed (in this case, to 1/125 sec.). This is usually done via one of the adjustment “wheels” on the camera. This type of exposure control shifting is a handy way to exert a little more control over the exposure settings than you’d have with the full-auto mode.
Besides allowing you to shift the exposure settings up or down, P mode also allows you to set the ISO and dial-in Exposure Compensation, which we’ll cover later.
Shutter Priority (Tv or S) Mode
Controlling things like the aperture setting and shutter speed will become very important to you as seek to gain more control over the look of your images. When you want to deliberately control shutter speed, or the duration of your exposure, Shutter Priority mode, often denoted with the symbols “Tv” (time value) or “S”, allows you to select and adjust the shutter speed as you shoot, while the camera automatically adjusts the aperture to compensate for any change in exposure. If you’re taking pictures at a sporting event for example, you might want to capture the images at shutter speeds no slower than 1/500 sec in order to freeze the action. As background and other lighting conditions change, your aperture will be adjusted automatically.
Of course, the camera’s ability to maintain good exposures through automatic aperture adjustments is limited by the aperture range of the lens used. In other words, if the camera would otherwise adjust the aperture to f/2.8 to compensate for a change you’ve made to the shutter speed, it can’t if the lens’ maximum built-in aperture is f/4. In those cases, a simple manual adjustment to your ISO will put you back into a good exposure range.
Aperture Priority (Av or A) Mode
This can be thought of as the flip side to Shutter Priority mode and can be found on your shooting mode dial under “Av” or “A.” You’ll use Aperture Priority when you want to have direct control of your aperture setting while allowing your camera to automatically adjust the shutter speed for you to maintain proper exposure. Although using this setting means you’re less concerned about the exact shutter speeds being used, you’ll want to keep an eye on the shutter speeds your camera is selecting for you. Stopping your aperture down too far can lead to slower shutter speeds and blurry pictures.
Manual (M) Mode
Manual mode (“M” on the shooting dial) gives you total control over all exposure settings: ISO, aperture, and shutter speed. This means you, and not the camera, are responsible for getting a proper exposure. The camera’s metering system will still provide you with feedback to help you judge the potential for over/under exposure, but it won’t take over to correct your exposure settings. Where lighting conditions are inconsistent, you’ll have to make frequent adjustments. Since you can freely adjust aperture and shutter speed independently of each other, you’ll find that you have a great amount of creative freedom with manual mode. But since you’re doing all the thinking for the camera (as far as exposure goes), you might be spending more time dealing with the settings than you’d like.
Manual mode is very useful in situations where you can take your time composing and making creative adjustments to exposure. It’s also great for studio lighting and portrait setups because in those situations the lighting conditions tend to remain constant throughout a series of shots; few if any exposure adjustments have to be made unless there are changes made to the lighting setup and/or the ambient lighting conditions.
Bulb (B) Mode
Another version of Manual mode is Bulb mode. Here, you can control all aspects of the camera as with manual, but instead of pre-selecting a shutter speed, the shutter simply remains open for as long as you hold the shutter release button down (or maintain the open shutter with a remote shutter release). This is a very inaccurate way to manage the duration of the exposure, but it can be useful under the right conditions. Bulb is best used with a tripod and some type of remote/cable release to prevent blur from camera movement. It’s often used to photograph fireworks, the night sky, and other low-light scenes.
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3. DSLR Camera Image File Formats
Of the many choices you have available via your camera settings, the file format you choose to save and export your captures in is among the most important. The type and size of your image files will determine certain limitations regarding editing and image quality. By understanding how Raw and JPEG file types can affect your workflow and the look of your images, you’ll be able to make informed decisions about image quality settings for your photography.
Image capture with a digital camera can be thought of as “data capture.” During exposure, your camera’s image sensor gathers information about the light and colors in the scene and this simple data comprises all of the optical information the sensor can record about that scene (see Figure 3.1). That data is translated and encoded into various implementations of what we generally refer to as Raw and JPEG files.
Metadata, information about the camera, lens, settings, time of exposure, and other details are usually stored along with each image file as shown in Figure 3.4. This information can be viewed in any software or file viewer that displays Exchangeable image file format (Exif) tags and data. This is a convenient record of when and how an image was created.
JPEG (.jpg, .jpeg)
JPEG refers to a technically defined standard for encoding and decoding digital images. There are many implementations and enhancements to the standard (determined by the Joint Photographic Experts Group) which we’ll refer to for our purposes as simply JPEG. This file format is probably the most ubiquitous and is quite useful for final versions of photographic images intended for digital display or printing. Even when the original digital image file is exported as a raw file, final versions of that image are often converted to the JPEG format for use. JPEG has the advantage of balancing space-saving data compression with acceptable image quality.
Capturing your images in a JPEG-only quality setting can be beneficial when you’re trying to conserve space on your memory card or other recording and storage media. This might also allow you to avoid extra steps during image processing. With this setting, your camera takes the digital image data normally stored in a Raw file and converts it down to a finished JPEG image for export.
Because much of the original image data is no longer needed, it is not saved along with the JPEG. At this point, the potential of the image (in terms of editing, correcting, and other adjustments) is greatly reduced because so much of the original information has been discarded. Alterations are still possible, but limited. This makes a JPEG-only choice an excellent one for images that will:
require little, if any, color and exposure correction.
undergo less scrutiny.
need to be delivered, printed, or distributed quickly (often straight from the camera or memory card).
take up less media storage.
Raw (e.g. RAW, CR2, NEF)
Raw files, unlike JPEG, contain the maximum amount of information about an image that you can export from your camera. Because of this, it takes up more room on your recording and storage media than a JPEG. But Raw data also provides you with the widest range of choices after export.
For our purposes, Raw refers to any of the file types produced by digital cameras that contain as much of the sensor and camera data as possible. The .CR2 and .NEF file types are Canon and Nikon versions of Raw, respectively, and many other types exist.
Raw files must be decoded by software, called a Raw file converter (see Figure 3.2.), in order to convert their rich but simple data into more defined image files. The Raw converter doesn’t alter the original Raw file in any significant way, it only creates a new image based on the original data and any applied settings. The settings that the Raw converter uses to generate the resulting image might be the camera settings you specified when taking the photo (recorded along with the Raw file), new settings you apply using the converter software, or a combination of both.
Because software packages like Photoshop and Lightroom make importing and converting Raw files fast and easy, there’s little downside to capturing your images as Raw files. JPEGs might eliminate an extra step in the process, and take up less storage, but they are also more limited when it comes to exposure adjustments and color correction during post-processing. Raw files provide you with a great amount of flexibility and options even after the original capture (see Figure 3.3).
You can produce many different high-quality JPEG versions of an image from a single Raw file, but if your only original is a JPEG file, major adjustments and editing can severely degrade image quality. Raw image files:
provide you with plenty of image detail and data to make reasonable adjustments without compromising image quality.
offer the maximum available image data, thus provide the potential for generating the highest quality images your sensor can record.
take up to several times the media storage than do JPEG files.
must go through a Raw file conversion process which adds an extra step before distributing, displaying, or printing images using the normal JPEG format.
do not have camera color balance, exposure, or other settings “baked-in,” so you are free to apply these adjustments (within the boundaries of the available data) after image capture.
Raw and JPEG Camera Options
Fortunately, many camera manufacturers have made the choices about which format to use easier by allowing both types to be recorded simultaneously. For example, your camera might allow you to record its highest-quality (highest resolution) Raw file and a JPEG at the same time. This gives you the option to use the JPEG version of the image for quick printing or distribution, while holding the original Raw file in case you need, for example, to adjust exposure or color balance. Recording to Raw files and JPEG at the same time takes up more media storage but gives you the convenience of both file types.
Other options on your camera might include combinations of smaller resolution Raw files and JPEGs of varying resolution and quality (compression) settings as shown in the menu view in Figure 3.5.
It’s good practice to record at the highest image quality possible given your time and storage constraints. Since the available software makes dealing with Raw files a quick and natural part of the workflow, its many advantages make it the best choice unless immediate JPEGs are necessary.
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4. ISO
In order for your camera to capture and record an image, hardware, electronics, and software must work together to first transform light from the scene into raw digital data. During exposure, the camera’s image sensor receives the light coming in through the lens while electronics keep track of how much light each individual photo receptor (pixel) is exposed to when the shutter is open. ISO is the camera setting we use to control the relative “sensitivity” of our camera’s sensor to light.
When you take a picture, the lighting conditions of the scene, as well as shutter speed and aperture settings determine how much light is striking the image sensor during exposure. ISO determines if that amount of light is enough to record a properly exposed image. If enough light strikes the sensor according to the ISO setting, adequate data is recorded for producing an acceptable image (see Figure 4.1).
ISO and Exposure
The sensor has a maximum amount of light that it is capable of recording (per each pixel). If that maximum is reached or exceeded, the data can only be interpreted as being the brightest possible tone. In our images, this is often what specular highlights or pure, blown-out white areas, are made of.
Conversely, it’s possible for the sensor not to receive enough light to record adequate data for all or part of a picture. It might be that the scene is too dim, or that your shutter speed and aperture settings are cutting down on the amount of light necessary to record the desired detail during exposure. Whatever the reason, less light striking the sensor can mean a darker image, or lack of detail in darker parts of the image.
If we had no way to adjust the sensitivity of our camera’s sensor, we’d always have to adjust shutter speed and/or aperture to suit such a rigid constraint. This might mean slower than useful shutter speeds in low light or smaller than desired apertures in brighter light.
By having a way to adjust how the sensor reacts to the amount of light reaching it, we are given more control over our aperture and shutter speed settings. As you’ll see in later sections, being able to control aperture and shutter speed allows for many creative options. This is why ISO, aperture, and shutter speed comprise the three main components of exposure; they all work together to give us total control over our exposures.
The camera’s ISO setting is our convenient way to tell the sensor to act as if it is more, or less, sensitive to the light during an exposure. A normal or low sensitivity response (normal or low ISO) allows the sensor to report light information under normal exposure conditions. Whereas a more sensitive response (higher ISO) might allow the sensor to report the same amount of light under lower lighting conditions.
Just as with aperture and shutter speed, adjustments to ISO can affect exposure and will cause an image to record as darker or brighter if aperture and/or shutter speed are not adjusted as well (see Figure 4.2).
ISO and Image Quality
How exactly does adjusting the ISO setting make the sensor more “sensitive” to light? It might be helpful to understand that in order for our cameras to deliver enough information from our sensors, sometimes that information needs to be “turned up” just like the volume on a sound recording when the recording is too low.
For example, say that you made a recording of a distant or very low sound. The signal is stored on the recording media, but in order to clearly make out the sound, you must boost the gain (or volume) which also makes some unwanted noise audible. With digital cameras, turning up your ISO is very similar; sometimes you need to “turn up” the signal in order to record enough useful information. The problem with amplifying the information signal is that, just like the sound recording example above, a lot of unwanted noise is also amplified. With our images, conspicuous noise (with a look similar to film grain) is a by-product of higher ISOs (see Figure 4.3).
The International Organization for Standardization is the authority over various technical standards. “ISO” is a sort of transposed acronym for this group that in photography has come to be used as notation for film speed and digital image sensor light sensitivity settings.
Choosing The Best ISO
Choosing the “best” ISO setting when you’re taking a picture depends on what you’re trying to accomplish. Generally speaking, most photographers would like to minimize unwanted noise in their images. This is often accomplished with lower ISO settings. So it could be argued that the best ISO setting you can choose is the lowest one possible that will work with your chosen aperture and shutter speed under the given lighting conditions.
Of course, since ISO, aperture, and shutter speed must be in balance to achieve a good exposure, any changes you make to one, affects the other(s). We’ll expand on how all this all works in the next few sections, but here is an example: Let’s say you can get a good exposure of a scene in natural light with the aperture at f/8 and a shutter speed of 1/125 second at ISO 400. It’s likely that your camera can record a slightly less noisy image at ISO 200, so you can set your ISO to 200 (half as sensitive to light as 400), and adjust your aperture to f/5.6 (twice as much light reaching the sensor than f/8). Either of these two combinations would provide you with a properly exposed image.
The following sections on aperture, shutter speed, and exposure will make exposure control interdependency more clear, but what you should understand now is that the best ISO in terms of minimizing unwanted extra noise in an image is generally going to be the lowest ISO setting on your camera that will result in a good exposure under the circumstances. Sometimes you’ll have no choice but to use very high ISO settings, but if you can get away with using ISO 800 instead of ISO 1600, go with the lower number.
Of course, sometimes the extra noise in an image is desired. Noise can contribute a sense of texture that reminds of us film, or just looks interesting. Not every image has to appear slick and noiseless. Knowing how your particular camera handles ISO and noise will help you make informed decisions about which ISO setting to use under various lighting conditions for the effect you want to achieve (see Figure 4.4).
Keep in mind that even if you must use higher ISO settings, most DSLRs are great at making unwanted noise less obvious. However, if you feel the noise in an image is not acceptable, image processing and editing software can diminish much of the noise for you, especially if you’re working with an original raw file.
ISO Setting Options
Your camera might have modes that will automatically select the ISO setting for you. In these cases, your camera might not choose the best ISO according to your preferences. Another feature of some digital cameras is the ability to use special low or high ISO settings outside of the normal range for the camera, and/or incremental ISOs like ISO 160 or ISO 320 (as opposed to ISO settings like 100, 200, 400, etc.).
In general, I recommend you start with the standard ISO numbers and adjust them in standard doubling or halving increments. It’s easy to remember that ISO 200 is half as sensitive to light as ISO 400, just as ISO 3200 is four times more sensitive to light than ISO 800. Simple.
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5. Aperture
In our everyday lives, our eyes are constantly being drawn to areas of interest; the people and objects we look at receive our visual (and mental) focus. Our eyes dart around — scanning, stopping, and focusing on the world around us. But our eyes aren’t really capable of focusing on more than one thing at a time, so while some areas of a given scene are in focus, other areas are not. The same can be said of our camera lenses. When we focus our camera’s lens on a nearby subject, objects at a good distance from the subject are usually out of focus. The area that is in focus can be thought of as a plane parallel to the camera sensor plane. The depth of this plane of focus (how much of the area around the subject is in focus) is called the Depth of Field (DOF) and it is controlled by adjusting your lens’ aperture.
What is Aperture?
When we think of camera lenses, we usually think of the clear optics in them that project the image of our scene or subject onto the sensor plane to create a photograph. But one of the most important parts of the lens is the built-in adjustable diaphragm that creates a hole (aperture) for the light from the scene to pass through, before it reaches the sensor (see Figure 5.1). By adjusting the aperture setting on your camera, you’re telling the lens how wide, or narrow, to make the hole. Because of the way the optics work, the diameter of the hole actually affects how much of the scene is in focus (DOF). Photographers will often refer to aperture settings in increments called “f-stops.” F-stops with lower numbers indicate wider apertures, whereas f-stops with higher numbers indicate narrower/smaller apertures (see Table 5.1 and Figure 5.4). Two examples of f-stop notation: f/1.8 (a wide aperture), f/16 (a smaller aperture).
Aperture and Exposure
As the aperture in the lens is adjusted up or down (wider or narrower) the actual amount of light moving through the lens in a given unit of time is going to change. Wider apertures allow more light to strike the sensor in less time than their narrower counterparts.
You can see that aperture actually affects two important things:
Depth of field (how much of the scene is in focus) as shown in Figure 5.2;
The amount of light passing through the lens onto the sensor (in a given unit of time) as shown in Figure 5.3.
While DOF relates to the parts of the image that are in focus, it’s the amount of light passing through the aperture, that affects our overall exposure. This is why aperture, along with ISO and shutter speed, is one of the three main components of exposure.
In order to get a good exposure, your camera’s image sensor must receive enough usable light from a scene while the shutter is open. Your ISO setting determines how much light the sensor needs during exposure. Your shutter speed controls the duration of exposure, and your aperture setting is going to control how much light the sensor is exposed to in that time. All three components have to be in balance in order to get a good exposure. By adjusting the aperture, we are able to adjust the amount of light the image sensor receives during exposure.
Table 5.1. Common Apertures. Many fast lenses start with f/1.8 which is actually a third-stop below f/2.8.
Choosing The Best Aperture
As stated earlier, your aperture setting (f-stop) controls both DOF and the amount of light your sensor receives during exposure. As with most things in photography, the “best” aperture is usually the best one for the job.
For portraiture and other imagery, most photographers find it preferable to visually isolate the subject from the background by keeping the subject in focus while other elements in the scene are blurred out of focus. So, for portraiture, wider apertures are generally preferred. Landscape and other imagery where much, or all, of the scene should be in focus will require narrower/smaller apertures.
In practice, sometimes what determines your choice of aperture setting is less about the creative use of DOF, and more about necessary adjustments for good exposure. For example, with an outdoor portrait under very bright conditions, even with your ISO on its lowest setting and your shutter speed at its fastest, using a very wide aperture might still result in an over-exposed image. In such a case, you’ll likely opt to adjust the aperture down to get a properly exposed image even though you’ll sacrifice a more pleasing, shallower DOF. Conversely, in very low light conditions, wider apertures are necessary.
Aperture Setting Options
Your DSLR has modes that allow for automatic aperture adjustments. Using these modes, your camera might not always choose the best apertures according to your preferences.
In cases where you’d prefer to maintain a set aperture, or control aperture directly, you’ll want to use Aperture Priority or Manual modes (see Shooting Modes for more information). Aperture Priority mode allows you to control the aperture while the camera makes automatic reciprocal adjustments to shutter speed to maintain good exposures. Manual mode also allows you full control over aperture settings but requires you to make the necessary reciprocal shutter speed adjustments on your own.
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6. Shutter Speed
As you’ve already seen, your camera’s image sensor must be exposed to light in a controlled way in order to properly record a picture. The mechanism that controls the duration of the exposure is called the shutter. The shutter’s job is to block the light coming in through your lens until you press the shutter release button to take a photo. When you press that button, the shutter slides open, exposing the image sensor to the light coming in through the lens (the projected image of the scene), then closes to block the sensor again, ending the exposure. Your DSLR is capable of a wide range of shutter speeds (see Table 6.1).
Usually, the shutter remains open for only a fraction of a second, but the duration can be longer. We refer to the length of time the shutter remains open as the shutter speed. Shutter speed is either controlled by the photographer directly, or by the camera in some automatic modes.
Shutter Speed and Blur
Your camera’s image sensor records any light projected onto it when you take a photo and the result is saved as a single still image. If there is no movement during exposure, the sensor only records stillness. However, if there is movement during exposure (either in the scene or from camera movement) it will may be recorded as overlapping areas of light in the frame. This produces blur, ghosting, light streaks, and other effects. Sometimes these effects are used creatively, as shown in Figure 6.1.
To help prevent blur due to camera movement, a tripod or monopod can be used. Image Stabilization (IS), Vibration Reduction (VR) and similar technologies are lens and camera features that can also assist in minimizing this type of blurring. While these will help minimize the effects of camera movement, they will not reduce blurring caused by movement in your scene — but faster shutter speeds will.
The faster the shutter speed, the shorter the duration of exposure; the sensor will have less opportunity to “see” anything move or change in the scene. Many compact and DSLR cameras are capable of shutter speeds as fast as 1/8000 of a second. At high speeds, you can capture images with virtually no motion blur regardless of subject or camera movement.
Slower shutter speeds are useful, too. In low light conditions slower shutter speeds offer the ability to capture a scene when higher ISO and wider apertures are not practical. In other words, in low light a slower shutter speed can allow enough time for the image sensor to collect enough light for proper exposure. Again, the tradeoff is that a slower shutter speed increases the potential for blur due to movement of the camera and/or the subject.
Shutter Speed and Exposure
As the shutter speed is adjusted up or down (shorter or longer durations of exposure) the actual amount of light reaching the image sensor, using a constant aperture, is going to increase or decrease. Slower shutter speeds allow more light to strike the sensor because the exposure is longer, while faster shutter speeds allow less light to strike the sensor (see Figure 6.2).
You can see that shutter speed actually affects two important things:
The amount of motion blur visible in an image;
The amount of time light is able to build up onto the sensor.
While the duration of the exposure affects the appearance of motion blur, it also determines the amount of light building up on the sensor which affects our overall exposure. This is why shutter speed, along with aperture and ISO, is one of the three main components of exposure.
As stated in an earlier section, a good exposure requires that the camera’s image sensor receive enough usable light from a scene in a given amount of time. Your shutter speed is going to control the duration of exposure, and your aperture setting is going to control how much light the sensor is exposed to in that time. ISO determines how sensitive the sensor is to the overall amount of light reaching it. All three components have to be in balance in order to get a good exposure. By adjusting the shutter speed, we are able to control the amount of time light is allowed to build up on the image sensor.
Choosing The Best Shutter Speed
Depending on the situation, it might be helpful to think about shutter speed in one of two ways; either as a creative tool to freeze (or express) movement, or as a tool for maintaining proper exposure. Keep in mind that your choice of shutter speed is going to depend on your aperture and ISO settings. One, or both, of these two settings might have to change if you’re making deliberate shutter speed adjustments.
If your goal is to take photos with minimal chance of motion blur, you’ll want to use a fast shutter speed. If you’re aiming to capture a sense of motion via creative use of blur, slower shutter speeds are called for.
Fast and Slow Shutter Speeds
The fact is, there are ranges of shutter speeds that will show little if any difference, from one speed to the next, where subject movement is concerned. For example, if you’re shooting portraits in the park on a sunny day, you’re not likely going to have to worry about movement blur with shutter speeds past 1/125 of a second (especially with a wide or normal focal length lens). But using shutter speeds slower than that might give you unwanted blur. Since you’ll probably be more concerned with creative use of DOF, your aperture will take precedence over shutter speed, so long as your shutter speed is above the aforementioned threshold. This is why Aperture Priority mode is useful outdoors in daylight; shutter speeds are determined automatically by the camera and generally stay in the higher ranges where there is little chance of detectable motion blur. In Aperture Priority, you control the aperture, while the camera automatically adjusts the shutter speeds as the lighting conditions change from shot to shot.
In low light situations, slower shutter speeds are generally called for because the image sensor requires more time to achieve a good exposure. Also slower shutter speeds can be useful with creative effects such as motion blur (see Figure 6.3), panning (see Figure 6.4), and “painting with light” (see Figure 6.5).
Shutter Speed Setting Options
Your DSLR has modes that allow for automatic selection of shutter speed. In these cases, your camera might not choose the best shutter speeds according to your preferences.
Shutter Priority mode allows you to set the shutter speed manually as needed (for example with sporting events, it’s often necessary to use shutter speeds above a certain range, say 1/500 second or faster). Aperture Priority and other modes adjust shutter speed automatically for you and are quite good choices as long as you make sure speeds remain in acceptable ranges.
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7. DSLR Exposure
When you depress the shutter release button on your camera to take a picture, the shutter opens, “exposing” the image sensor to the light coming in through the lens. The quality of this exposure will greatly affect the look of your image. In many cases you’ll allow your camera to make some (or all) of the decisions regarding exposure via its program modes and metering system. This is fine, but a skilled photographer also knows how to manage their own camera settings in order to really control the look of their photos. Understanding how exposure works is key to becoming a skilled photographer. This section will likely be your most challenging, but it will be worth it.
In the previous sections we discussed how ISO, aperture, and shutter speed are not only useful creative tools, but also the most important components of exposure. You might have also picked up on the fact that they are interdependent; any change made to one of these settings requires a reciprocal change to another to maintain the same overall exposure. In this section, you’ll learn more about how ISO, aperture, and shutter speed relate to each other during exposure.
Keep in mind that just because you can get the same exposure using different combinations of ISO, aperture, and shutter speed, it doesn’t mean that all combinations will result in identical images. Combinations using slower shutter speeds and smaller apertures may result in blur, while faster shutter speeds and wider apertures will give you less blur and shallower DOF.
Measuring Light
We control exposure by controlling the quantities of light reaching the image sensor with a given ISO. In order to do this in a consistent way we need a standard, easy-to-follow system of measurement that ties into our camera settings. And while your camera may allow you to make adjustments to these settings in various increments, including 1/3 steps, we are going to discuss exposure using the traditional unit of light/exposure measurement, the basic, “stop.” A stop is a unit of light (or exposure) measurement that doubles with every increase.
The following are examples of one-stop differences:
If you start with an f-stop of f/8.0, and change it to f/5.6, you will double the amount of light coming in through the aperture (f/5.6 is 1 stop wider than f/8.0).
If you start with an ISO of 200, and change it to ISO 400, you will double the sensitivity of the sensor to light (ISO 400 is twice as sensitive to light as ISO 200).
If you start with a shutter speed of 1/60 second, and change it to 1/30 second, you will double the amount of time light is allowed to pass through to the sensor.
Consequently, going the other direction with any control “halves” the light, time, or sensitivity:
If you start with an f-stop of f/8.0, and change it to f/11, you will halve the amount of light coming in through the aperture (f/11 is 1 stop narrower than f/8.0).
If you start with an ISO of 200, and change it to ISO 100, you will halve the sensitivity of the sensor to light (ISO 100 is half as sensitive to light as ISO 200).
If you start with a shutter speed of 1/60 second, and change it to 1/125 second, you will halve the amount of time light is allowed to pass through to the sensor.
While standard ISO setting increments are straightforward (100, 200, 400, 800, etc.), other settings are a little less so. Full-stop increments in shutter speed might not always be divisible by 2, and aperture f-stops are not labeled with simple numbers. Still, knowing that each standard incremental adjustment from one to the next results in a full-stop difference is what’s important.
In the following sections, we’ll go into more detail about how this works from the perspective of each of the three major components of exposure.
Aperture
As stated previously, a camera exposure adjustment can be thought of as either halving, or doubling light (or light’s effect on the sensor). For example, given a consistent amount of light and the same amount of time, going from an f-stop of f/2.8 down a full stop to f/4.0 is effectively cutting the amount of light passing through your lens in half. Conversely, adjusting your aperture setting from f/5.6 up a full stop to f/4.0 doubles the light passing through your lens. Aperture affects the amount of light allowed through your lens in a given unit of time. You might think of it as a light “valve” that provides a hole of varying size for the light to pass through (see the previous section, Aperture).
There are f-stops between the full-stop values we’re discussing. For example, there are 1/2-stop and 1/3-stop values. But to keep the concepts simple here, we will use examples featuring full-stop values.
Aperture also affects depth of field (DOF), which is something we discussed earlier. The numbers associated with f-stops might not be intuitive, but the important thing to remember is that they are standard and allow us to measure light as described here.
It’s important to realize that your camera can only make aperture adjustments based on the limitations of your lens. You can’t dial your aperture up to f/2.8 or f/1.8 if your lens’ widest aperture is only f/4.0. It’s advisable then to purchase the best and fastest lenses you can afford (“fast” referring to lenses capable of wider apertures of at least f/2.8). These will give you the best optical quality and the most versatility in terms of DOF and exposure.
Shutter Speed
Shutter speed is the time factor in your exposure. It is the unit of time your camera allows light to pass from the rear of the lens onto the image sensor.
Shutter speeds are most often fractions of a second. For example: 1/60, 1/125, 1/250, 1/500, etc. Discounting a few unusual looking increments (after 1/8 we have a 1/15 setting, and after 1/60 we have a 1/125 setting), from one of these settings to another is a full stop as shown previously in Shutter Speed.
There are also speeds between these full-stop values, but to keep the concepts simple here, we will use examples featuring only full-stop values.
Again, given a consistent amount of light passing through the aperture, from one standard shutter speed to the next, we are either halving or doubling the duration of exposure, which halves or doubles the amount of light allowed to pass through to the sensor. Moving from 1/250 to the twice as fast 1/500 cuts the time light is allowed to reach the sensor by half. Thus, moving from a shutter speed of 1/250 to the twice as slow 1/125 doubles the amount of time light is allowed to reach the sensor.
ISO
Your camera’s ISO setting controls the image sensor’s sensitivity to light. It’s the final part of the light pipeline we are concerned with during exposure. The higher the sensitivity of the image sensor, the less light needed in a given unit of time to record a good exposure.
As with the aperture and shutter speed settings, changing ISO settings can either halve or double the amount of light (in this case the “effect” of the amount of light reaching the sensor). However, the numbers involved tend to be more straightforward.
An ISO setting of 400 indicates twice the light sensitivity of an ISO setting of 200. If you can get a correct exposure with an ISO setting of 400, then you can get a similarly correct exposure if the ISO is set to 200 AND you adjust accordingly the aperture and/or shutter speed to make up the difference. In other words, if everything is set for a good exposure of a scene, and you change the ISO to be less sensitive to light, you’ll have to allow more time for light to build up on the sensor (via a slower shutter speed), or allow more light to go through the aperture in the same amount of time (via a wider aperture), or both.
A side effect of forcing the recording media to be more sensitive to light is that an increase in noise might be noticeable (see ISO).
The Three Controls in Combination
Given the amount and type of light we have to work with when taking a picture, finding the balance we desire of these three components: aperture, shutter speed, and ISO is always our (or the camera’s) goal. You might adjust one, two, or all three in various ways, but all three have to add up correctly to create the exposure you want. And there is more than one way to get that exposure as shown in the following tables and in Figure 7.1.
For example, with regard to exposure, if we start off with the following combination for a given constant amount of illumination on our subject:
All four exposure setting combinations above will result in the same exposure. An example of this is shown in Figure 7.1 below.
In the case of flash illuminated subjects, shutter speed plays less of a factor and adjustments you can make for flash exposure on the camera are basically limited to ISO and aperture. There is a little more to it than that, but the takeaway right now is that shutter speed shouldn’t be thought of as a way to control flash exposure.
So, in a nutshell, we generally measure light in “stops” and control it with aperture, shutter speed, and ISO. Within any of these components, each standard incremental change either doubles our light (or its effect), or cuts it in half. We have to balance these components and compensate for a change in one, with a change in the other(s) to get similar exposures across adjustments.
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8. DSLR White Balance
For achieving accurate color in your images, the White Balance (WB) setting on your camera can be very helpful. Different types of light and how that light bounces around in the environment can affect the way color appears in your images, often showing up as blue or orange color casts. These color casts aren’t something we tend to notice in everyday life. Our minds automatically compensate for them by perceiving white objects as true white, even when we’re looking at those objects under the orange/yellowish glow of lamp light or candle light, or in the blue light of an overcast sky. If we take photos without the correct WB applied, our cameras will produce images with the warmer or cooler colors we didn’t notice with our eyes.
Video: White Balance and Color Temperature
The WB setting tells your camera how to compensate for these color casts with the goal of achieving true white for white objects in the scene (see Figure 8.1 and Figure 8.2). The reasoning is that if you achieve accurate whites, the other colors aren’t being affected by a color cast, either, and they will consequently reproduce accurately.
Here is a list of several common WB settings and what they’re used for:
Auto. With Auto WB, your camera estimates the best WB adjustment for the scene. Auto will not always give you the most accurate results, but it is a good choice if you don’t want to deal with WB settings while shooting.
Daylight, Shade, Cloudy, Flash. These settings help compensate for the bluish (cooler) colors associated with outdoor/daylight and flash lighting.
Tungsten. This setting helps compensate for the orange (warmer) colors associated with incandescent lighting.
Fluorescent. This setting helps compensate for the greenish colors associated with traditional fluorescent lighting.
Kelvin. If you’d like to dial-in a specific color temperature as your WB setting, use this. It can be great for fine-tuning the WB.
Custom or “White Card” setting. After photographing a known white surface under the lighting conditions you’ll be shooting in, you can use that image to calibrate your WB setting. This is usually accomplished by having the camera prompt you for the image of the white surface. The camera then uses the color cast in the image to determine a good WB adjustment for subsequent photos. A neutral gray card can also be used. See more about this in Gray Cards and Color Reference Charts later in this section.
We often talk about color casts by referring to the Kelvin scale which specifies a range of color temperatures (in degrees Kelvin) associated with the visible color spectrum. The bluer, or cooler, colors appear in the higher temperature range with daylight and flash illumination being around 5,500 K. Incandescent lighting (light bulbs) are in the 3,200 K range (see Figure 8.3).
With the proper WB setting, the camera will compensate for a color cast range when producing a JPEG (or it will record the WB setting in the Raw file for use during Raw conversion). This is useful when the color temperature of the light sources are all similar in a scene (e.g. flash used as fill light in bright daylight conditions where both types of lighting are approximately 5,500 K). When lighting is mixed, however, the WB cannot be set to compensate for completely different color casts at the same time. But there are solutions to this problem which we’ll discuss next.
Flash and Ambient Lighting
To highlight the problem of WB in mixed lighting, we’ll look at a common situation involving flash and ambient light. When you use flash for indoor photography, you will often have the cool color temperature of flash in the same scene with the warm color temperature of incandescent lighting. Here are three options for dealing with this type of mixed lighting where WB is concerned:
Auto WB. Let the camera handle it. This will generally result in good color balance indoors, although there will be noticeable warm tones in background lighting as shown in Figure 8.4. This is because the automatic WB setting will give the flash priority since it is illuminating the subject. This will insure the flash illumination does not appear blue in the scene, which would be the case if the WB were trying to correct for the incandescent (tungsten) lighting.
Use a CTO gel. You can attach a filter over your flash head called a Color Temperature Orange (CTO) gel as shown in Figure 8.5. This essentially turns the light emitted from your flash into an orange color, somewhat matching the color of incandescent lighting. With this in place, your flash and the ambient light will all be in the same color temperature range so a WB setting of tungsten will correct for the whole scene.
Correct in post. Color corrections can be made to selected areas of a photo in your image editing software. Instead of making color adjustments to your entire image at once, use selective techniques to change the colors in parts of the image. This solution tends to be more time-consuming because each image needs to be corrected individually. See more below in, Correcting for WB in Post-Processing.
Correcting for WB in Post-Processing
You can make WB adjustments to your image during post-processing using tools found in software like Adobe Lightroom. This can be as easy as clicking on a neutral color in an image, allowing the software to make the correct adjustments to achieve proper WB. Below, is a photo taken in a NYC subway station under fluorescent lights (see Figure 8.6). The shot was taken with the camera set to AWB. The first image shows what it looked like in Lightroom using the settings applied by the camera (“As Shot”). The second shows the same image after applying Lightroom’s default setting for Fluorescent WB adjustment. The third shows the WB adjustment after I used the WB adjustment eyedropper to select one of the neutral gray areas on the color chart. It was this last method that gave me the most accurate colors.
Mixed Lighting, Mixed Color Casts
Adjusting for a color cast is pretty straight-forward, but a problem might arise if you’re using mixed lighting (lights of different color temperatures). Your camera can only compensate for one color cast at a time. So when you have more than one potentially unwanted color cast in a scene, you have a problem.
I have to admit that I really don’t worry about this kind of thing very much. My approach is to simply get a decent WB setting in camera for the image in general; really I just want to make sure the subject isn’t affected by a color cast. If I’m shooting with flash, and there are tungsten lights in the background (maybe as part of the environment; candles, fireplace, accent lights, etc.), those might look just fine appearing as warmer colors and lights. In some cases, it might look natural to see these warmer colors somewhat reflecting off the subject. If I don’t like some of the colors appearing in an image, I will often selectively adjust them in post as shown in Figure 8.7. This means, I’ll adjust the colors to parts of the image as I see fit.
Gray Cards and Color Reference Charts
As I mentioned earlier, a neutral gray card (often called an 18% gray card, but I’m not really sure about the accuracy of that term) can be used by the camera or post-processing software to help make WB adjustments. You’ll have to consult your camera’s manual if you want to learn how to do custom WB on your camera. In post-processing, any area of neutral color can be used to quickly, automatically make WB adjustments.
Some color reference charts have specially produced color swatches that can help you get very accurate color matching results. I’ve been using the DKC-PRO Digital Kolor Card – Pro 5×7 (see Figure 8.8) because it’s small enough to fit into my backpack and has a large series of swatches that cover a range of white to black in 6 steps. On the back, is a large offset printed neutral gray card that does the job.
You can use a simple gray card or reference chart under any lighting conditions, or anytime you’d like to be able to get a good WB or have a known color reference in your images.
But that’s just the beginning of the story
These are all tools that are helpful for achieving correct color. If you’re aiming for accurate color, it’s important that your monitor be correctly calibrated, too. Without that, your colors might be way off, and once you get the colors in a shot looking correct on your screen, they might actually be more blue or orange on other screens, or in the prints you order.
There are different schools of thought on reproducing “correct” color. I mean, sometimes it’s necessary to reproduce colors as accurately as possible, but other times, not so much. Even if you manage to get those colors right, who’s to say they’ll look right on someone else’s monitor, or once they come back from the printer? Even if a print depicts the colors accurately under white light, those colors are going to look very different when viewed under tungsten light. So, I really don’t worry about that kind of thing very much, unless color accuracy is critical. I just make sure the colors look good to me, and convey the feeling I want. I’ll even throw in a color cast sometimes if I think it looks good.
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9. DSLR Metering Modes
Getting good exposures with your camera is a result of providing the right amount of light to your sensor. Of course, the “right” amount of light is going to be based on the given sensitivity of the sensor (ISO) and what you are trying to achieve with the picture. As you’ve seen in previous sections, ISO, shutter speed, and aperture settings are the three components of exposure that must be in balance for a proper (or desired) exposure. With your ISO set, the aperture and shutter speed are the two controls that determine how much constant/ambient light is provided to the image sensor. Metering is how we measure light intensity so that we can know what aperture and shutter speed settings we need to use for the exposure we want to achieve.
When taking photos in automatic and semi-automatic shooting modes like Full Auto, Program, Aperture Priority and Shutter Priority, your camera will use the information from its internal meter to automatically adjust one or more settings to maintain a proper exposure for the scene.
Here is a list of common metering modes for DSLR cameras (note that your camera might use different nomenclature for these standard types of metering):
Evaluative/Matrix Metering. This is considered a general purpose metering mode that uses intelligent programming to identify what type of scene you’re photographing, and which areas to prioritize for metering, so the camera can adjust exposure accordingly.
Center-Weighted Metering. This can be visualized as a combination of Evaluative/Matrix and Partial metering modes. Here, the center area of the frame has priority but the lighting in the rest of the frame is also taken into account.
Partial Metering. A small area in the center of the frame is metered rather than the overall scene. Useful when you want to expose properly for a subject in the middle of the frame and not have the meter take strong background lighting into account.
Spot Metering. With spot metering, a very small area of the frame is metered. This is good for times when you want more precise metering on a small area of the scene.
In practice, you’ll probably want to leave your camera set to Evaluative/Matrix as it will provide accurate results for most shooting situations. As you encounter scenes that are out of the ordinary in terms of subject placement and illumination, you might find that one of the other metering modes is more suited to a particular situation.
Exposure Compensation
Despite what your camera meter might determine as being the best aperture and shutter speed settings, you might find that you’d prefer the subject and/or background to appear a little brighter. Without changing the actual lighting in the scene (with reflectors, additional light sources, moving your subject, or adding flash), you’ll have to adjust the exposure overall. You can leave your camera on its current shooting and metering mode and simply override the camera’s exposure settings via the Exposure Compensation (EC) control. Doing this is as easy as dialing the appropriate control wheel to move the exposure level indicator up or down the meter scale. For example, if you’d like the subject to appear a bit lighter in the picture, you might dial-in +1 stop in the exposure indicator. To make the subject appear less bright, you might dial-in -1 stop. For more about compensation controls see 100% Reliable Flash Photography.
Locking in a Meter Reading
In some cases it might be useful to use the camera to meter a scene or subject and lock that information in before taking the actual picture. For example, you could take a meter reading of the scene, knowing that the background might become brighter as conditions change or you recompose the shot. By pressing your camera’s auto exposure lock (AE/AE-L), you will let the camera know to take a meter reading and store it for the next shot, or subsequent shots.
What About Metering For Flash Photography?
The light metering we’ve discussed in this section is for constant, non-flash lighting. These metering modes are suitable for metering and determining the exposure based on ambient lighting conditions. Flash metering is handled by another system in the camera (TTL) that sends out a preflash, reads it through the lens, and determines what the flash output will be for the actual exposure. This all happens automatically as you press the shutter. Some new to flash photography don’t realize that the flash metering and exposure are separate from the regular metering and exposure. Not only are the light readings taken separately, but compensation adjustments can be handled with different controls; EC for normal Exposure Compensation, and FEC for Flash Exposure Compensation.
In contrast to the usual flash control provided by the TTL system as described above, manual flash photography is not metered by the camera at all. With manual flash, you set the power of the flash unit(s) yourself. Often, this is where a handheld flash meter can be useful, as there is no mechanism on your camera to meter manual flash.
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10. DSLR Drive Modes
Pressing the shutter release button on your camera usually results in a single image being captured. But in certain drive (or release) modes, you can initiate a burst of exposures, often more than two or three per second. The drive/release modes also let you set self-timer and remote release controls.
Most of the time, we take photos using a basic single-shot mode. This is great for portraiture and relatively static subjects where you’ll take at least a few seconds between shots to compose and capture your images. However, with sports or other action photography, it might be helpful to take a series of continuous shots. Sometimes a sequence of shots helps tell a story. Other times, the goal is just one good shot, and by capturing several images in quick succession, you’re hoping to find at least one in the sequence that you like.
Many cameras are capable of continuous bursts exceeding 3 frames per second (fps), with some able to shoot up to 8 or even 12 fps. The upper limits of these burst modes aren’t always achieved however because they are somewhat dependent on other camera settings and modes including focusing, exposure, image quality settings, flash, and the capacity of your memory card.
Here are some of the drive/release modes offered on many DSLRs:
One-shot: A single image is taken when you depress the shutter release button. You must lift your finger off the button and press it again to take another picture.
Continuous/Burst: The camera continues to take pictures as long as you hold the shutter release button down. Some cameras offer a Low and a High setting allowing you to vary the number of frames per second. Some things to be aware of:
- Your flash may not be able to keep up with a long burst of exposures. Damage to your flash can occur.
- Focusing can be an issue; continuous auto-focus is usually the best way to go for moving subjects, but use a mode that maintains the original focus if necessary.
- Since the shutter release button remains depressed during continuous shooting, the camera may not be able to adjust exposure as lighting conditions change.
Timer: Self-Timer modes release the shutter and take a picture on a time delay. This allows the photographer to set the camera on a tripod or some steady surface and include himself in the picture. In self-timer mode, the photographer depresses the shutter release button but the camera waits a set number of seconds before actually taking the picture. Good for self-portraits and group shots including the photographer.
Remote Release: This mode also frees the photographer from having to be at the camera position to take the picture. A cable or other remote device is attached to the camera and triggered from a distance. This also allows the photographer to be included in the picture, while still giving them full control over the exact time they want to release the shutter. Many photographers will also use remote releases to prevent camera shake, photograph wildlife, or to work on stop motion animation projects.
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11. DSLR Focus Modes
Manual focus is available with many digital cameras and lenses but automatic focus (Autofocus/AF) is more often employed because of its reliability and ease of use. Today’s cameras are equipped with multi-point AF technology that can achieve and maintain tight focus on still as well as moving subjects. In Full Auto mode, your camera will likely make all focusing decisions for you, including the focus mode and points of focus within the frame. Other modes will give you more options where focus is concerned. Check your camera’s documentation for instructions on how to select the various AF options with your camera.
Here is a list of AF concepts you should be familiar with:
Focus modes for still and moving subjects. Many cameras have a focus mode that is suitable for still subjects (often called “One Shot” or “Single Servo”) and another for moving subjects (often called “AI Servo” or “Continuous Servo”). While focus is activated, the one for moving subjects will continually track and focus on the subject as it moves. When the shutter button is fully depressed the camera will attempt to accurately predict focus for the moment of exposure.
AF points. These are small areas of the frame designated as AF control points; objects in the scene appearing directly in line with these AF points are the ones that will be used for focusing decisions. These points can be chosen automatically by your camera, or manually selected by you. Depending on the model, your camera may have anywhere from a small number of AF points to more than 50. Sometimes AF points are grouped into zones which can result in more accurate automatic focusing in challenging shooting situations.
AF Assist. Cameras and external flash units often come equipped with AF assist features which enable your camera to focus in darker environments when that might not otherwise be possible. AF assist can come in the form of a visible red or white beam of light from an external or built-in flash.
Single point focusing. Many photographers like to use only one AF point to set focus on a subject. If the center AF point is used, the photographer will usually press the shutter button half way (or another designated focus button), achieve focus, and recompose just prior to taking the photo. This method of focusing is not recommended for moving subjects because the other AF points are not used and therefore cannot provide multi-point tracking.
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12. DSLRs & Flash
Using your camera’s flash can open up a world of possibilities for your photography. If your camera has a pop-up flash, activating it can be as simple as pressing a button. In Full Auto mode, the flash will activate automatically when the camera detects low light. In this case the flash is activated in order to prevent slower shutter speeds that could result in blur. In other modes, using flash is optional. Although we’ll focus on the basics of using built-in flash here, more powerful and versatile external flash units are also available. There are also many advanced techniques you can apply to your flash photography which you can explore in other resources like, 100% Reliable Flash Photography.
When is Flash Needed?
Flash lighting can be useful in many situations, but it’s not always the best choice. Quite often, ambient and natural light is all that is needed for great looking pictures. But, flash is required if you want to take a picture when the environment isn’t providing sufficient light to work with your desired camera settings to achieve a good exposure. Of course, you can always adjust ISO, aperture, and shutter speed to record an image in otherwise very dim light, but unacceptable noise and blur might be introduced. Even when high ISOs and low shutter speeds can be avoided, for a subject receiving much less ambient illumination than the background is receiving, flash is usually the appropriate solution. Finally, flash is a good way to freeze the action in an environment that would otherwise call for slower shutter speeds.
Flash Exposure Compensation
Before we move forward with this section I want to start by discussing Flash Exposure Compensation (FEC). Simply put, FEC is a setting that allows you to control/override the output (power) setting of your flash. It might surprise you to know that your flash does not always produce light of the same intensity; in certain modes its output is automatically adjusted according to several conditions including existing light, distance to your subject, and the various camera settings in use. This automatic output control of your flash is handled by a system generally referred to as through-the-lens (TTL) metering and flash exposure control. Here, an almost imperceptible pre-flash is fired to “test” the flash against the scene so that the camera can calculate the correct amount of flash to fire during the actual exposure.
What the FEC setting on your camera does is allow you to override the automatically determined flash output. In other words, you can use FEC to dial-in more, or less, flash if you feel it will improve your picture. An FEC setting of -1 will tell the flash to emit one stop less light than TTL calculated for your picture (or half the flash power originally determined). A setting of +1 will tell the flash to emit one stop more light than TTL calculated for your picture (or twice the flash power originally determined). FEC is just an easy way to lower, or boost, your flash’s power while still relying on TTL’s automatic flash control as the baseline (see Figure 12.1).
I should note that TTL is not the only type of flash control available. Many cameras allow for the manual control of flash output, but this is a less flexible option that is better suited to static shooting situations. TTL automatically adjusts output so you and your subject can move freely, and camera settings can be changed, without worrying about manually resetting the flash output to compensate for those changes.
Flash as Main Light
Your camera’s built-in flash can be used as the main light source for pictures taken in low light situations. Because the flash is small and positioned so close to the camera body, thus the lens, it not only produces a rather harsh light, but also unnatural light pattern. The light is striking your subject not from a side angle but from straight-on. This causes the shadows to be projected straight back and the light to decrease in intensity quickly from the front of the subject to the farthest part of their form, to the background as shown in Figure 12.2. We lose the sense of dimension provided by a more natural shadow pattern, and often get darker backgrounds than we expect. But sometimes, you need that extra light, and if the built-in flash is all you have to work with, that’s what you use.
Using flash as the main source of illumination can be as easy as any point-and-shoot photography; set your camera to Full Auto mode and take a photo in low light. Full Auto will even detect back lighting conditions and activate the flash when it thinks it will help.
In modes other than Full Auto, you can follow these steps to use and adjust your flash when it’s your main light source:
Select a camera shooting mode, an appropriate WB and activate the camera’s built-in flash so it’s ready to go. Make sure your flash is set to operate in TTL mode and that FEC is set to “0” compensation (see your manual if you need instructions on how to do this).
With your subject at a normal distance of between 5-10 feet away, take a shot and view the results on the LCD monitor.
If you feel the illumination from the flash is too bright for the subject, set your FEC to -1 to lower the flash output by one stop.
If you feel the illumination from the flash is too dim for the subject, set your FEC to +1 to raise the flash output by one stop.
Make incremental changes to FEC until you are happy with the way the flash is illuminating your subject. Remember to reset FEC back to “0” when finished.
You can also use EC to adjust the way the background light appears in your images while maintaining the flash exposure you desire for the subject. How and to what extent you can use EC is going to depend on your camera mode and is an advanced topic we won’t get into here. But I encourage you to learn more about it in your camera manual and 100% Reliable Flash Photography.
Flash for Fill Lighting
Often, when people think of flash photography, they think of pictures that have that typical bright “flash” look to them. The use of flash is certainly called for when there isn’t enough light in the scene to capture your subject the way you’d like, but flash can also be used in subtle ways to enhance a picture. Fill flash, for example, allows you to add a little extra illumination to an outdoor daylight portrait. Shadows often need some light brought in for a more balanced look and to reduce contrast. Fill flash adds just enough light to the subject to get the job done (see Figure 12.3). This is one area where FEC comes in handy as it allows you to adjust the amount of fill flash to your taste.
Here’s how to apply fill flash to an outdoor daylight portrait:
Position your subject so that they are not facing the sun. This can be in an area of shade or with the sunlight coming in from behind them. You should notice that the background lighting is brighter than the illumination on their face.
Select a camera shooting mode, an appropriate WB, and activate the camera’s built-in flash so it’s ready to go. Make sure your flash is set to operate in TTL mode and that FEC is set to “0” compensation (see your manual if you need instructions on how to do this).
With your subject at a normal distance of between 5-10 feet away, take a shot and view the results on the LCD monitor. If you are using your camera’s Full Auto mode, it will provide the amount of fill flash it thinks is appropriate for the scene. If you are using a mode that allows you to adjust the flash output via FEC, continue to the next step.
If you feel the illumination from the flash is too bright for the subject, set your FEC to -1 to lower the flash output by one stop.
If you feel the illumination from the flash is too dim for the subject, set your FEC to +1 to raise the flash output by one stop.
Make incremental changes to FEC until you are happy with the way the light on your subject is balanced with the light in the background. Remember to reset FEC back to “0” when finished.
Built-in vs. External Flash Units
There’s no doubt that external flash units designed for use with your camera system provide superior performance to the built-in variety (see Figure 12.4). External flash units provide several advantages including:
More powerful output. Mid- to high-end units offer substantially more lighting power than smaller and built-in flashes. This means they give you better reach and more intensity when you need it.
Higher position over the camera. As the flash moves farther from the lens axis, a more natural lighting pattern starts to develop on the subject. True, when simply mounted on the camera, the change in distance is only several inches, but it does help.
Bounce lighting is possible. Better external flash units have flash heads that can be tilted and rotated to point in different directions. This gives the photographer a tremendous opportunity to bounce the light emitted from a powerful flash against the ceiling and/or a wall opposite the subject. Large, even illumination and beautiful pictures can result.
Off-camera capabilities. This is the game-changer; when you are able to position your flash units to illuminate the subject from any direction in the scene the possibilities are endless. And TTL makes it easy to setup, use, and balance flash just as you wish. There are also powerful manual techniques you can use to assume precise control over your flashes for studio-quality lighting.
Attachments and modifiers. In order to create more sophisticated looks, several modifiers are available that will help you control the quality of the light coming from your external flash. Gels to help maintain WB, diffuser attachments to help scatter the light around a room, and off-camera modifiers like shoot-through umbrellas (see Figure 12.5) can give you lighting that rivals that of any professional studio.
Other Flash Features
Here is a short list of some other flash features you might find useful:
High-Speed Sync. With compatible external flash units, your system will be capable of High-Speed Sync or FP Sync. This feature allows your camera to use shutter speeds faster than the normal speed recommended for flash with your camera (often up to the highest shutter speed your camera is capable of). This can be useful for daylight fill flash photography but you should be aware that High-Speed Sync necessarily results in much weaker flash than what you’ll get when using normal flash sync and slower shutter speeds. Use it if necessary, but avoid it when you need more powerful flash output.
Front and Rear Curtain Sync. Since the burst of light from your flash is of a much shorter duration than any shutter speed normally used with flash, you have a choice as to when you want that burst to happen. Basically, you can set your camera to fire your flash near the start of the exposure, or close to the end. This becomes a factor when ambient light is being recorded along with flash. Front curtain sync will fire the flash at the beginning of the exposure and terminate, while the rest of the exposure continues to gather any ambient light it can. Rear curtain sync will fire the flash near the end of the exposure, after most of the ambient light was recorded. One effect of using front curtain sync is that motion recorded as light streaks from a moving subject show the streaks ahead of that subject, whereas rear curtain sync will result in showing the streaks behind the subject in a more natural “follow” pattern.
Multi/Stroboscopic Flash. This is a mode on your flash that creates a series of flashes in a single exposure. This is good for special effects showing an action sequence where the subject’s movements are displayed as discrete flash exposures within an exposure. Uses for this feature are probably limited for most types of photography and it’s important for you to be aware that firing your flash too many times in rapid succession can damage it.
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13. Evaluating Exposure and Making Adjustments
The technology behind your DSLR’s automatic features can make getting good exposures easy for even the most inexperienced photographer. But that technology isn’t perfect. Much of it relies on internal metering and algorithms that can only make a “best guess” at the settings to use in any given situation. Whether you’re shooting in a program mode or in manual mode, you should take advantage of one of digital photography’s best features: the instant preview. By occasionally checking your shots on the LCD monitor, you can verify, among other things, that your images are properly exposed and make any necessary adjustments accordingly.
The LCD monitor provides you not only with simple previews of your images, but also useful numerical and graphical data about each image. In this section, we’ll discuss three important image evaluation tools that you can use to improve your images as you shoot. Check your manual for instructions on how to quickly activate and access these useful tools.
The Histogram
It’s easy to get frustrated because you can’t see the preview image clearly under bright light. Times might also arise where you’re second-guessing what the preview is showing you because you’re not sure if the brightness setting on the LCD is too high or low. The histogram is a quick way to view what your camera is recording about an image’s tonal values when other methods are not as precise. With the knowledge you’ll get from that data, you can make quick, informed adjustments to your exposure settings.
Your camera’s histogram displays a bar graph detailing the distribution of tones in an image from darkest to brightest with the darker tones to the left and brighter tones to the right (see Figure 13.1). Each tiny bar represents one shade or tone in the image with the height of that bar representing the number of pixels the image contains of that tone. The histogram is somewhat reminiscent of mountain peaks and valleys. The valleys are tones that appear infrequently (or not at all) in the image and the peaks are the tones that appear most often. Note that although the bars in the histogram are clustered, this does not indicate that those tones are clustered in the actual image. Each bar simply indicates how often a particular tone appears throughout the image.
With that in mind, it’s easy to understand what the histogram says about a particular photo. If most of the image contains very bright areas, the histogram will show most of the higher bars to the right of the graph. If most of the image contains very dark areas, the histogram will show most of the higher bars to the left of the graph. A photo with plenty of middle tones will display a cluster of bars around the middle areas of the graph. Histograms with displayed zones, delimited by visible vertical lines on the graph, give you an idea of how the values fit into the dynamic range of the sensor. The middle zone is where the medium tones are, while the zones just to the left and right of the middle zone are -1 stop, or +1 stop, respectively. The two zones farthest to the left and right of the graph are -2 and +2 stops, respectively.
How is the histogram useful for evaluating exposure? Having a graphical view of the distribution of all the tonal values can help you know what’s going on with an image in ways that might not be obvious in the regular image preview. One thing to keep in mind is that the histogram is most useful when you have an idea of what it should look like based on the type of image you’re capturing. There is no single “correct” histogram, because there is no single “correct” type of image.
Two things to look for when evaluating a histogram:
Blown-out highlights. If your image contains brighter/whiter areas there is always a chance that those areas might have been overexposed, even though other parts of the image seem fine. If the histogram shows high bars on the very right edge of the graph, it means you have a lot of pixels making up the pure white tones lacking any detail. Many photographers try to avoid getting too many pixels of this type in their images.
Low-key, High-Key. Most of the time, you’ll want to see a nice distribution of tones across the graph, but this isn’t always the case. If you’re shooting dramatic low-key images a histogram showing the concentration of bars to the left of the graph is expected. Likewise, a high-key image will show the concentration of bars closer to the right.
There is also a color channel histogram available that gives you an indication of the distribution of pixels for each of the red, green, and blue (RGB) values. As you might surmise, this is a useful feature for analyzing how color is being captured.
The Highlight Alert/Warning
As stated earlier, as far as exposure is concerned, many photographers try to avoid blowing-out the brighter areas of the image. Looking at a normal preview, if everything else in your shot seems fine, you might be more concerned with retaining the detail on a white bridal dress, for instance, than worrying if the rest of your image is drifting slightly to the left on the histogram. By enabling the camera’s highlight alert (also called the highlight warning), you’ll be warned with every shot about potential highlight area problems. The LCD will display your image as usual, but with the added “blinking” effect superimposed over the areas in the image that have blown details (see Figure 13.2).
Keeping with the bridal photography example, when shooting images featuring the bride, it might not matter if some areas of the image show the blinking highlight alert, but if your bride’s dress is blinking, you’ll want to dial down the exposure on subsequent shots so the blinking (and overexposure) disappears off the dress, at least.
The Overall Preview
The standard LCD monitor preview is probably the most important tool for assessing your images as you shoot. It will give you quick visual feedback regarding composition, focus, depth-of-field, motion blur, white balance settings, and the overall look of your images as shown in Figure 13.3. It will also provide you with a general look at the quality of your exposures. In most cases, you won’t have to pull up the histogram view or enable the blinking highlight alert because the regular preview will give you a good idea of how your images are turning out. However, taking the occasional look at the other exposure evaluation tools, while shooting a series of images, can help you avoid exposures that are slightly off the mark. And keeping an eye on the highlights and the right side of the histogram will let you know that you’re not losing important detail in the brighter areas of your images.
Exposure Adjustments with EC and FEC
When you determine changes to your exposure settings are necessary, all that may be required to correct any issues are simple Exposure Compensation (EC) and/or Flash Exposure Compensation (FEC) adjustments. How and to what extent these controls work is determined by several factors including the camera mode you’re using.
Full Auto mode. In Full Auto, the camera may not allow access to compensation controls.
Program mode. EC adjustments will affect aperture and shutter speed settings.
Aperture Priority mode. EC adjustments will affect shutter speed settings. Dialing EC to -1, for example, will increase the shutter speed, while dialing it to +1 will decrease the shutter speed.
Shutter Priority mode. EC adjustments will affect aperture settings. Dialing EC to -1, for example, will stop down the aperture by one f-stop, while dialing it to +1 will open up the aperture by one f-stop.
Manual mode. EC is not really a factor when manual camera settings are being used. This is because any changes to exposure are accomplished via direct and deliberate adjustments to aperture, shutter speed, and ISO. In this case, you’ll simply change the settings that suit you.
The adjustments you can make to EC are also limited by the use of flash. For instance, although EC affects shutter speed, it can’t adjust it to a speed faster than the flash sync speed (unless High-Speed Sync is available, as with external flash units). Another important thing to note is that with some camera/flash combinations, making an adjustment to EC will automatically force a change in FEC.
FEC adjustments are similar in that you can dial-in more, or less, brightness on flash-illuminated portions of the image.
Bracketing
Where time allows, some photographers will employ bracketing techniques to cover a range of exposure settings for a single shot. This gives them the option of choosing the best shot in a sequence rather than making individual exposure adjustments as they go. You can set your camera to take a series of images according to a bracket range you specify using Auto Exposure Bracketing (AEB) as shown in Figure 13.4. For example, you might setup your bracketing to make a -1, 0, and +1 (or one stop under, normal, and one stop over exposed) series of shots. Be careful to reset or turn off bracketing when you don’t intend to use it or you might be surprised by unexpected exposure results.
Exposure Adjustments in Post
When shooting Raw image files, you’ll always have a little wiggle room in your exposures for corrections, especially if you don’t exceed the practical limits of what the sensor was able to record of the highlights and shadows. When your camera is set to only save JPEGs, however, you lose most, if not all of your ability to save the detail in slightly blown-out highlights. When the camera saves to JPEG, only the data that matches up with your camera settings is saved, the rest of the data, including the detail that might have been available in the highlights, is lost. This is why I recommend Raw files over JPEG for image capture and export.
Exactly how you can make exposure adjustments to a Raw file after the fact is going to depend on the type of software you have available and the tools that are most appropriate for those adjustments. In applications like Adobe’s Lightroom or Camera Raw, you can use Raw editing and conversion features to improve the overall exposure, recover detail in the highlights, and adjust the mid-tones. With some applications, selective adjustments are possible; you can make adjustments to portions of an image rather than the image as a whole. JPEG image editing is also possible but less data is available in a JPEG file so the potential for adjustments will be limited.
Note: A convenient pdf download of this guide is also currently available.
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