The Auto-Focus (AF) function of modern digital cameras is simply amazing, especially when using a Digital SLR (DSLR). In most instances shooting in AF mode will result in a sharp, crisp image that rivals the ones you’ll take by focusing manually. But there are some situations in which you’ll get better results by focusing manually, and others where Manual Focus (MF) will be your only practical option. Here are a few tips to help you recognize when you should opt to focus manually:
1 – Low-light photography
Most digital cameras have trouble focusing automatically at night or under extremely low-light conditions. You can usually tell when this is the case because the camera will “hunt” by zooming in and out as it tries to find a clearly defined subject to focus on. If it fails to find one, the camera usually won’t even attempt to take the photo and an error message will be displayed. In instances like this your only option will be to focus manually.
2 – Close-up (macro) photography
All auto-focus lenses have a minimum distance between lens and subject at which the auto-focus function will work properly (usually several inches) . If you place the camera closer to the subject than this distance, you’ll have to focus manually.
3 – Portrait photography
When shooting portraits, it is almost always desirable to ensure that the eyes are in perfect focus, a task that is very tricky indeed when using the camera in AF mode. By focusing manually, you can concentrate on the eyes and get the results you are looking for.
4 – Shooting a “crowded” scene
When shooting a subject in a crowded scene, your camera’s AF will often have difficulty finding the subject that you wish to focus on. For example, if you’re trying to focus on just one of the individuals in a group, you’ll probably have to focus manually to get the desired effect.
5 – Wildlife photography
As in #4 above, photographing a bird in a tree or an animal peeking out of some underbrush will almost certainly require manual focus as there will be branches or other objects for the AF to “find” and focus on.
Conclusion: Sometimes you’ll simply have no choice except to focus manually in order to get a decent shot. To do so using a DSLR, you usually have to flip a switch on both the lens and the camera body from “AF” to “MF”. Many point-and-shoot cameras require you to change a menu setting. Your camera’s user manual will provide instructions if you need them.