I often see Internet discussions where a newcomer to the world of photography posts a question about which mode to use when photographing a specific subject, and invariably there will be someone who claims that one should only shoot in Manual mode because that’s the way the pros do it. After all, you upgraded to a DSLR so you can better control the camera—not so you can let the camera do all the work, right?
The fact is, most professional photographers use some form of automatic settings for the majority of their work. The two most common exposure modes are Shutter Priority, also called Time Value (Tv), and Aperture Priority, or Aperture Value (Av). In the truest sense, these two exposure modes are semiautomatic, since they require the photographer to control at least one aspect of the exposure settings. If everyone bought DSLRs so they could manually control every aspect of focus and exposure, then the manufacturers wouldn’t spend millions of dollars of research designing and improving upon things like metering and autofocus because it would all be done in the photographer’s head.
Almost no photographer looks at a scene and intuitively knows the exact exposure. You can use the "Sunny 16 Rule" as a jumping-off point, but every scene is different and must be taken as such.
Most photographers who shoot Manual exposure use the camera’s built-in light meter, the same light meter that the camera uses when determining settings in automatic exposure modes. The photographer is using his or her brain to decide which combination of shutter speed, aperture and ISO will get the image created expressively, but he or she still is relying on the camera’s ability to accurately measure light for the actual exposure.
What if you could choose your settings for creative purposes, but allow the camera to do most of the work when it came to adjusting for those settings? The good news is that, with most DSLRs, you can!
First and foremost, I’m not recommending using the fully automatic point-and-shoot mode that most cameras have, often referred to as the "green" mode because of the icon that commonly denotes it. I’m also not recommending the little brother to the green camera mode: the fully auto flash-off mode. These modes don’t allow the photographer any creative flexibility at all.
The key to making automated settings useful is to take control of them by knowing how they function and by setting parameters for them to work within. When you know what the camera is doing and why, the automatic settings aren’t so unpredictable after all.
PROGRAMMED AUTO, OR P MODE
Cameramakers know that most photographers not only want control of their cameras, but they also would like to control them in the easiest way possible. For this reason, companies include what’s usually called the Programmed Auto (or simply Program) mode on even their top-tier professional models. This is one of the most misunderstood, and therefore most underutilized, exposure modes.
Unlike the green camera mode—which chooses all settings, including exposure, flash, ISO and white balance—Program mode controls only the aperture and shutter speed settings. This leaves the rest up to the photographer. When in Program mode, the camera doesn’t randomly choose an aperture and shutter speed; it uses parameters that are preprogrammed into the camera’s firmware.
The parameters are quite simple. In low light, the aperture is fully opened and the shutter speed is set as needed to get a proper exposure according to the metering method you’ve selected. As light increases, the camera will shorten the shutter speed until it reaches a speed that’s the reciprocal of the focal length of your lens (the handholding limit).
From there, the aperture is stopped down and the shutter speed shortened alternately until one of the settings maxes out. As you may surmise, this isn’t necessarily the best mode to use if you want to achieve a specific effect in your photograph, such as controlling depth of field or portraying motion.
The good news is that when using Program mode, you still can easily modify camera settings to suit your needs. You can engage Flexible Program or Program Shift (depending on your camera system), which allows you to adjust the shutter speed and aperture settings as you see fit. Simply rotate the appropriate command dial until you achieve the aperture or shutter setting that you want, and the camera takes care of the corresponding setting.
If you know which aperture setting or shutter speed you want for a particular effect, why not use Shutter or Aperture Priority settings? The answer is that, when using these semiautomatic settings, the camera doesn’t necessarily take advantage of all data that’s available. For example, when using Aperture Priority, the camera doesn’t take into account the focal length of the lens and attempts to keep the shutter speed fast enough to reduce camera shake, as it does in Program mode.
Program mode may not be the best option for all shooting situations, but it’s very handy for photographing scenes when you want to focus your attention more on composition and less on settings. Since you can physically adjust the settings on the fly, it’s more flexible than most people think.
Auto ISO takes one aspect of the exposure trio out of the equation and allows you to focus on the more creative settings of aperture and shutter speed. Auto ISO is less automatic than the name may lead you to think it is. Auto ISO settings can be programmed by the photographer to fit a certain criteria. Setting these criteria is a very important step to follow so that Auto ISO functions best.
Not all camera systems have the same feature set, but most current cameras allow you to set a limit on the highest ISO sensitivity setting that can be automatically selected. This is a key feature of Auto ISO. Capping your ISO sensitivity to a setting that you can live with is the most important part of the feature. Each camera is different, and every photographer has different criteria of acceptable noise, so the parameters for settings won’t likely be the same for everyone, but most current cameras are good up to at least ISO 1600.
Some camera systems, such as Niko
n, allow you to set the minimum shutter speed that the camera will attempt to maintain before increasing the ISO sensitivity. On the newest Nikon cameras, there’s an auto setting that allows the camera to adjust the minimum shutter speed setting of the Auto ISO feature according to the reciprocal of the lens focal length rule. You also can adjust this setting to be biased toward faster or slower shutter speeds. Once you enter your preferred parameters, you can almost forget about setting the ISO at all.
Using Auto ISO in Manual exposure mode gives you the best of both worlds. You have 100% control of the creative settings of aperture and shutter speed, while the camera controls the exposure according to the metering mode you choose by adjusting the ISO sensitivity.
Auto settings won’t cover the bases for every situation. In controlled environments, or when going for a specific effect, setting the shutter speed, aperture and ISO manually may be the best route to get optimal results.
Different situations call for different settings, and there are definitely situations where using automatic settings are extremely useful. If controlling depth of field isn’t an important consideration, Program mode can be an easy option to use when lighting is sufficient to get a fast enough shutter speed to avoid blur from camera shake.
When shooting in a busy environment, where the lighting is constantly changing, such as a wedding or an event, using Auto ISO can be extremely helpful. Setting the parameters to your acceptable levels will allow you to get usable images across the board.
Setting the parameters of your camera’s automatic features constrains your camera to your acceptable limits and takes the unpredictability out of the auto settings, freeing you up to focus on the creative side of your photography rather than the technical side.
Check out J. Dennis Thomas’ “Nikon Digital Field Guide” at nikondfg.com.