Controlling depth of field is a matter of using aperture settings (mostly) and lighting (to a lesser extent). We’ve discussed this subject above, but here are a few more tips and thoughts. When you want to bring a single subject to the foreground as the focal point, a shallower depth of field is the best approach. Having your subject be sharply defined while the rest of the photograph remains blurry and out of focus can bring more attention to your subject and avoid distractions. Portrait photographers do this a lot. However, there are some cautions that should be kept in mind.

One cautionary note involves avoiding a cluttered but blurry photo. If your background is busy but out of focus, this can actually detract from your subject by drawing attention to blurred objects that are hard to recognize. The mind wants to ask, “What the heck is that thing?” rather than simply letting the background be background. With shallow depth of field, you want the objects in the background to phase into one another so that none of them draws attention in particular but all of them serve to frame the main subject. With a busy background, if there’s no way to compose the picture so as to reduce the busy aspect of it, the best approach is often to use a wide depth of field so that all of the objects are in focus. Use another method, such as framing, to draw attention to the main subject. A DSLR camera has (usually) three different modes of focusing which are set with a control. These are AI servo focusing, one-shot focusing, and manual focusing. One-shot focusing allows you to use one control in one position (usually depressing the shutter button partway) to automatically focus on the focal point (by default the center of the frame, but this can be reset to some other location), after which the picture is taken and the focus is lost. You have to do the same process again to focus on a different focal point (or on the same one). This is the way autofocus used to work on all cameras prior to the digital revolution, and it’s still the most common, popular, and easy to use method. AI servo focusing allows you to hold down the shutter control and take pictures in rapid succession, click, click, click. The camera focuses automatically on the focal point (again, by default and normally the center of the frame) before each picture is taken. This allows you to take multiple shots of a moving target far more easily than you would be able to do with one-shot focusing. Finally, manual focusing is just that. You turn the camera’s AI off and use the Force – that is to say, you set the focus manually by looking through the view port and seeing whether it looks like it’s in focus or not. This is a good idea when doing macro photography, because the tolerances for focus are quite small, and the autofocus is more likely to make small errors that translate into a blurred subject when taking close-ups. It’s also a good technique for shooting landscape pictures at night, when the autofocus finds it difficult to lock onto the target Most DSLR newer cameras allow you to combine autofocus and manual, letting you fine-tune the focus after the autofocus has locked in. As long as you have the time to use it, this is often the best of both worlds.