I began my photography career as photojournalist for newspapers. At the time it was a field dominated by men who held certain, hardcore values. One of which was that it was a sign of weakness to use a tripod, auto focus or auto exposure. I was young and easily influenced at the time so I tried hard to live up to that standard.
Eventually I realized that both auto exposure and auto focus are great tools. When used properly, they can free you up to think more about your image composition and the scene unfolding in front of you. Plus, what good is a great photo if it is improperly exposed? And, I must admit, I even use tripods from time to time now as well.
Auto exposure settings vary from camera to camera. I am a Canon user. But it is universal to have these camera settings:
– Automatic or Program (P): the camera automatically sets the shutter speed and aperture to suit the subject’s brightness.
– Manual (M): you set both the shutter speed and aperture desired.
– Aperture Priority (AV): you set the desired aperture and the camera sets the shutter speed automatically to obtain correct exposure suiting the subject’s brightness.
– Shutter Priority (TV): you set the desired shutter speed and the camera sets the aperture automatically to obtain correct exposure suiting the subject’s brightness.
I don’t ever use the fully automatic setting. I use the manual setting when indoors or at night most of the time. But I use both aperture and shutter priority constantly when outside. For instance, if I am outside photographing children running around I use shutter priority (TV) to make sure the shutter speed is fast enough to capture the fast action (ie. 1/250 or higher). Or another example would be if I am taking a landscape photo of beautiful scenery, I would use aperture priority to make sure I had deep depth of field (ie. f/11 or higher).
Autoexposure isn’t perfect. A camera sees a scene as grey. The camera doesn’t have a smart, flexible, sentient brain like you. Because they are designed to accurately capture a scene that has an average reflectance of middle gray, your camera is puzzled by setups that don’t fit this ideal. Sometimes you have to override the camera’s auto settings just a bit using exposure compensation. Let’s begin by looking at some of the most common situations where your automatic exposure system will have a problem and then explore how you can easily achieve perfect exposure.