Customizing AF Functions

Learn about autofocus from a professional photographer.

What is Autofocus?

Autofocus is a camera function that allows you to focus on a subject automatically. In other words, your camera searches for a subject and focuses on them without you having to adjust the focus. Today, most cameras you can buy in the store have this feature. It might sound pretty self-explanatory, but there are different ways to use and customize your AF functions. 

Autofocus has become so advanced and easy to use that photographers very rarely feel that they can benefit from using manual focus. Most digital cameras are quite accurate when focusing on a subject, so you might never need to photograph in MF mode.

AF Settings

There are several different modes of operation you can choose from when you want to make use of the autofocus function. These are the 3 main modes present on my Canon camera:

One Shot AF

One shot AF, also known as single area AF or single AF, is used for subjects that are not moving. For instance, you can use this mode of operation when you’re shooting a model in a studio. The camera acquires focus and maintains it when the shutter opens. Thus, if you did not manage to acquire focus or the subject moves, the photo will reflect that. 

AI Servo AF

AI servo AF, also known as continuous AF, is suitable for shooting a subject that is in motion. You can use this mode of operation for events, sports photography, and other. The nature of this autofocus setting is a lot more complex than one shot AF. A lot of work and technology goes into predicting subject movement. Camera manufacturers implement advanced artificial intelligence to increase the accuracy of these predictions. The good thing about this setting is that the camera will keep re-focusing as the subject keeps on moving.

AI Focus AF

AI focus AF, also referred to as AF auto or hybrid mode, is a setting that enables the camera to switch between one shot AF and AI servo AF automatically. As a result, the camera is able to decide when you’re working with a subject in motion and should use the latter, or when the subject is stationary and you can use the former. This is an excellent mode to start with, when you are not entirely sure how to shoot your subject yet.

AF Area Modes

Your camera focuses on the subject by choosing one or several points in the frame. By doing so, it can focus rather well or not at all. It’s important to understand the way you want your camera to focus in order to take clear and crisp photos. Each type of photography has its own preferred AF area mode. Here are some you should remember:

Manual AF Point Mode

Also known as the single point AF area mode, this mode creates only one point of focus in the photograph. You can move the focus point to the side. This mode is great for photographing buildings and landscapes, as well as other subjects that are not in motion.

AF Point Expansion Mode

Also known as the dynamic AF area mode, this mode allows you to work with subjects in motion. You only need to pick one focus point initially. Once the focus point has been acquired and your subject begins to move, the camera will use the points surrounding the main focus point to keep the subject in focus. 

Automatic AF Point Selection Mode

This mode is also referred to as the auto-area AF mode. The mode is very advanced. It decides what to focus on and how to get the job done based on the subject of the photo. In other words, the camera takes full control of who and what to focus on when you’re shooting in this mode. It can recognize skin tones and will automatically focus on the people in the frame. If there are multiple people in the picture, the camera will pick up on the ones closest to it. It is an interesting mode to work with, but it’s not suitable for photographers who like to have more control over their focus point. 

Pinpoint AF Mode

This mode is only available on Nikon cameras and it’s used in photographing very detailed scenes with a stationary subject. The way it works is that the autofocus narrows down to a very tiny point in the shot. You can move the focus to a different point within the frame.

Group Area AF Mode

This is another exclusive Nikon-only AF area mode. This mode uses a whole of 5 focus points to track your subject. It’s great for subjects that are moving too quickly for you to be able to acquire focus with just one point. You can also use this mode in the beginning of the shoot when you don’t feel confident enough to only choose one focus point. 

What Settings Should You Use For Sports?

As a professional sports photographer, working with subjects in motion is my day-to-day. Finding focus can feel very peculiar when your subject literally never stops. I recommend starting with AI servo AF. AF point expansion is probably the best AF area mode to use with moving subjects. Alternate between different modes depending on who your subject is, how close you are to the subject, and how fast the subject is moving.

Conclusion

Delivering the sharpest image you can is a big part of photography. Unless you are attempting a blurry and abstract masterpiece, you need to utilize autofocus. Autofocus functions will help you keep your image clear and your subject in focus. Unlike other camera settings, there is not too much wiggle room with autofocus modes. You need to find the best suitable mode for the type of photography you’re doing and stick with it. Despite the seemingly strict guidelines, you can play with your settings and find out what works best through trial and error. Keep in mind that practice makes perfect!

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