Pressing the shutter button

It's time to discuss how to press the shutter button on your camera. Now I know that may sound a little patronizing, particularly when I talk like this. But it turns out that that simple button press triggers a fairly complex chain of events, and you need to be aware of those events when you press the shutter button. If you don't understand everything that happens, you could miss shots, or end up with images with bad exposure or bad color. So, to work through what we're going to cover here, you first need to switch your camera to program mode. We covered mode changes earlier, so you should be comfortable with this.

In the days of all manual photography, before you took a shot, you framed it, then you focused, then you dialed in your exposure settings, and it was only after doing all of those things that you could take a shot. You still have to do about all of those things, but the good news is that your camera can probably do them for you, and it probably does a very good job. The way you start this process is to press the shutter button down halfway. Now, if you take a moment now to feel your shutter button, and I mean feel what happens when you press it, you'll find that it is pressing it all the way down, but then there is also a halfway point, a little stop that you can feel.

When you press to this point, you're telling the camera to start working on all of those decisions that need to be made before it can shoot. The first decision is autofocus. When I press halfway, my camera's autofocus mechanism springs into action and calculates focus. Next, a light meter in my camera measures the light in the scene and calculates the shutter speed and aperture that'll give me a good image for that particular light. That is, an image that's neither too bright nor too dark. Now finally, the camera also calculates white balance. This is a process that will improve the chances that the colors in my scene will look correct.

Now this is all a fair amount of work, and it can actually take some time, especially if you're trying to focus in low light. Well, once it's made all of these decisions, your camera will beep at you and possibly flash a little light in the viewfinder. This lets you know that all the necessary preparation is done, and you're ready to shoot. Now, you press the shutter button the rest of the way, and the camera takes the shot. Now it's absolutely critical that you always half-press, hold there, wait until the camera says it's ready, and then press the rest of the way.

If you just mesh the shutter button down all the way, the odds are you're going to miss your shot, because your camera has to chug through all of those steps before it can take the picture. It's a much faster than you would be doing it if you were doing it yourself, but it still takes some time for your camera to do this. If you've experienced that problem of trying to capture a particular moment, and you press the button, and the camera doesn't take the picture when you thought it was going to, that's probably because you've mashed it all the way down. So if you're not already used to this process, then you need to start practicing it, because this half-press step is going to be critical for some of the more sophisticated light metering that we'll be doing later.

Autofocus, metering, white balance, these are all complex operations, and we're going to talk about all of them in great detail as we continue.