AF, what does it mean in photography? To be precise, it is a system for automatically focusing the image on a given object. AF is one of the most important camera functions for the professional photographer.
The vast majority of photos are taken using AF, disabling it only in very rare cases. But if situations where you need to shoot with manual focus are rather the exception, there are an incredible number of scenes using autofocus.
Autofocus for the best focus on your subject
Autofocus dramatically increases shooting speed for simple subjects such as landscapes and portraits. It is irreplaceable when shooting portraits with a shallow depth of field, because the slightest movement of the model can lead to a shift in focus.
In a portrait, the focus should be in front of the subject’s eyes, and if the focus has shifted to the nose or ears, this is a serious mistake. Autofocus – AF, which is set before each new photo is taken, makes it easy to avoid this.
In genre and reportage photography, where great photographer response is required, the fast autofocus helps you keep the shot. For example, it helps a lot when photographing moving subjects – cars on the road or people walking down the street.
Street photography without autofocus will become impossible for most photographers as it is quite difficult to focus on moving subjects. And some scenes become possible to shoot only with good AF. First of all, this is important when photographing very fast moving objects, for example during sports competitions.
What are autofocus modes and for which scenes?
A camera can have two key autofocus modes, AF-C and AF-S. They differ greatly from each other and are used in different scenes.
- AF-S is simple focusing on a stationary subject. The camera focuses once and locks the focusing distance. This mode is great for shooting still or slowly moving subjects in landscapes, portraits and architecture. However, if the subject is moving quickly and you shoot in AF-S mode, the pictures may be out of focus. The fact is that after pressing the shutter button, the subject already has time to leave the focus area. This happens very often when photographing people moving towards the photographer, cars, in sports.
- These scenes use the AF-C (Auto Focus) mode, which constantly monitors the subject and adjusts the focus based on the movement of the subject. At the same time, because the AF-C constantly tracks the subject, it is not recommended for shooting static models as the focus may accidentally extend.
Cameras have an arsenal of autofocus activation options. Firstly, it is a traditional shutter button, when pressed halfway, the camera focuses, and when pressed all the way, it takes a picture.
For the photographer, this means that each button can be assigned a separate function, significantly speeding up the work on shooting. Whether you’re shooting weddings, sports coverage or street photography, fast focusing can help you capture that precious photo.
Why is it important to choose the right autofocus point?
I mean, which is better – manually or automatically? Another key point in working with autofocus is choosing the right focus point. If you choose the wrong focus point, there’s a good chance your shot will be out of focus. The camera will simply misjudge the shooting conditions, and some details will remain blurry.
For simple scenes, the chance of error is low, but the more complex the scene, the more likely it is to get a blurred shot.
The camera is able to select the focus point automatically using various parameters. For example, it could be fully automatic, it could be face detection focusing, or it could be advanced 3D tracking technology.
Most professional photographers select the AF point manually to have full control over the image. At the same time, the camera offers a wide range of advanced automatic focus point selection functions.
For example, for simple scenes, it is enough to use the fully automatic mode. Suitable for simple landscapes or portraits.
Face detection focusing is ideal for portraits, weddings, street photography. 3D tracking and point tracking is an advanced feature for capturing moving objects. But despite the development of automation technologies, automation and creativity are different things. Therefore, in most cases, the photographer uses manual focus point selection to control the frame as much as possible to create it with his own hands.
For static objects, it uses single-point focusing. To do this, it moves the focus point to the desired part of the frame where the main subject is located. For example, in a scene with a car against the background of mountains, the photographer may focus on the car because that particular detail of the image was supposed to be perfectly sharp.
For action scenes, AF-C with group or dynamic focus points is often used. In this case, the camera monitors the subject with several sensors and helps not to miss the focus at the most important moment.