If your camera has priority controls (Shutter and Aperture in addition to full Manual), it likely also has a “P” alongside the A, S, and M. That “P” stands for “Program,” but as we’ll see today, it might as well stand for “Pray.”
Program mode is theoretically supposed to be like Automatic, but with a degree of control. This works fine in principle; the camera makes decisions for you based on how your scene and subject are lit, but you have control over ISO, exposure compensation and flash. Some cameras also allow flexibility within Program, so that you can alter either the shutter speed or aperture as well. In those cases, it should theoretically be like having both Aperture and Shutter priority in a single control option. In practice? Picture playing whack-a-mole with your SLR.
Here’s the problem: we saw in the previous weeks’ tutorials that when the camera allows you to choose one variable (say, your aperture), it automatically takes control of the other to give you what it thinks should be the optimum exposure. The problem with shooting in Program, as with shooting in full Auto, is that there are many combinations of shutter speed, aperture and ISO that will get you the same exposure in the same lighting conditions, but sometimes the choices the camera makes won’t be ones that you’re comfortable with. Sometimes it’ll give you the quicker shutter speed you’d like, but make you sacrifice aperture for it; conversely, you can also try for the slower shutter speed only to find out that more of your background is in focus than you’d like. Sometimes slight under- or over-exposure is needed to get the rest of the photo to look the way you wanted (or you may even have a preference, as some people do, for one or the other as a general rule). Program takes some degree of that control from you. What’s worse, several frames taken in sequence under the same light can have different shutter and aperture values.
This is especially a pain if you’re trying to use exposure compensation; if you dial in a -.3 exposure compensation, you can still end up with shots taken under the same conditions being exposed unpredictably. As you get used to your camera’s quirks, it becomes easier to predict when it will go to one side or the other of a medium exposure, and to compensate accordingly.
Setting shutter and aperture is similarly problematic; you may find the thumb wheels unresponsive for a few tries, to a point where it’s like trying to figure out the button combination in a video game. That’s all well and good if I’ve got a character from Street Fighter in my viewfinder, but otherwise I expect my camera to behave like a camera rather than a game console.
It’s entirely possible that I’m doing something wrong here; I know a couple of photographers who absolutely swear by Program mode. To my mind, the purpose of having controls in the first place is just that: control. Anything that adds unnecessary guesswork to the equation isn’t terribly useful. But then, your mileage may vary.
Program can be good in situations where there’s a lot of action (sports and street photography), though it’s a good idea to check your photos frequently if you’ve set the aperture to make sure it hasn’t picked a default shutter speed that’s too low. It can be downright lousy when you have the time to compose your shot and a very definite idea of the settings you’d like to use (and sacrifices you’re willing to make). On that note, in the next two weeks we’ll be putting together the lessons of the last few weeks and shooting in Manual.