Suppose you’ve been taking pictures with your digital camera for a while, and you’re wondering why some of your pictures look so much better than others. Or suppose you’ve noticed that somebody else’s pictures look a lot better than yours, and you’ve decided it’s time for you to do something about it. What should you learn? Well, if you’re a beginner, it’s very likely that you need to learn to understand exposure better.
This article is my attempt to teach somebody who is in the habit of letting the camera set the exposure how to take control of it themselves. I hope this will get you started with the basics. There is immensely more to be learned, but I’m not qualified to teach it all, and you don’t want to try to learn it all at once anyway, it’d just bury you in details. If this gets you started, I’ve done my job, and you’ll be able to understand more advanced articles on exposure when you’re ready for them.
These instructions are for digital cameras. The meaning of setting an ISO differs between digital cameras and film cameras; the other two are the same.
Despite common usage, you should remember that exposure is a matter of opinion. There is no objective “right” or “wrong”; there is only “what you want” and “not what you want”. The purpose of taking control of your exposures is to be able to get “what you want” more often.
There are three controls on your camera that affect exposure: shutter speed, aperture, and ISO. Each of these things affects both the exposure and one other aspect of the picture. Often getting the picture you want is a matter of balancing different effects to get a compromise you can live with.