Button Cameras: How Do They Focus?

Button cameras, like other cameras, can use back-button focusing. This is a camera technique that separates focusing and shutter release into two separate buttons. The autofocus function is taken away from the shutter release button and reassigned to another button, usually on the back of the camera. This allows the photographer to lock the focus on a subject or scene and then recompose the shot before firing the shutter. This is particularly useful for wildlife photography, where the subject is often moving, and for situations where the autofocus system struggles, such as when the subject is hidden behind a complex foreground element or in low light conditions.

Back-button focus separates the shutter release and autofocus functions

Back-button focus is a camera technique that separates focusing and shutter release into two separate buttons. This means that the autofocus function is taken away from the shutter release button and reassigned to another button on the back of the camera. This can be any physical button, but most advanced digital cameras have a dedicated AF-ON button for back-button focusing.

By default, cameras are set up so that when you half-press the shutter release button, the focus system engages and tries to focus on your subject. Then, when you apply a bit more pressure, the shutter trips and an image is captured. This essentially means that the single shutter release button is used for two different purposes – one to focus and one to take a picture.

Back-button focus simplifies this process by moving the focusing function to a dedicated button. Any time you need to focus, refocus or continuously track the subject, you engage the focusing button. If you need to take a picture, you engage the shutter release button. There is no need to remember which focusing mode you are using, because you can always keep your camera in AF-C mode.

Advantages of Back-Button Focus

Back-button focus has several benefits:

• Shoot in AF-C with the benefits of AF-S: The dedicated focusing button is only engaged when you need to focus, so you can keep your finger off it when you need to lock focus and simply keep taking pictures.
• Instant manual focus: Since the camera's autofocus is only engaged when you press the dedicated focus button, you can take complete control of the manual focus on most lenses without your camera overriding the focus when the shutter is released.
• Shoot stationary and moving subjects: Back-button focus can be advantageous when you need to quickly transition from shooting a stationary subject to one that is moving.

Disadvantages of Back-Button Focus

There are a few drawbacks to back-button focus:

• Requires excellent coordination: It can take time and practice to master pressing two buttons to do a job you previously did with one.
• Challenging shooting conditions: It can be difficult to maintain the high coordination needed for back-button focus when shooting with a heavy lens or when you are tired. This is especially true in very cold weather conditions.

It allows you to combine manual, single and continuous focusing modes

Button cameras, or cameras in general, have different focusing modes. These include manual, single, and continuous focusing modes.

Manual focusing mode (M) allows the photographer to decide where to focus instead of letting the camera do it. This is useful for astrophotography, low-light conditions, and genres like macro, architecture, and stills.

Single autofocus mode (AF-S) is the most basic option available. The camera will lock the focus on the subject that you want to photograph. This is best for static subjects, such as portraits, macro, and architecture.

Continuous autofocus mode (AF-C) is best for moving subjects. The camera will continue to track the subject, even if they move around within the frame. This is most useful when you’re photographing moving subjects – from athletes running on the football field to kids playing on the beach.

By combining these three focusing modes, photographers can be prepared for a variety of situations and subjects. For example, when shooting a portrait, one might use manual focus to ensure the eyes are in sharp focus. If the subject is moving, one can use single autofocus mode to lock focus on the subject, and then switch to continuous autofocus mode to track their movement.

You can lock focus independently of the shutter release

Back-button focus is a camera technique that separates focusing and shutter release to two separate buttons. It is a useful way to stop the camera’s autofocus system from getting continuously engaged when the shutter is released. The name comes from the fact that the autofocus function is typically activated using a button on the back side of the camera.

Back-button focus is achieved by reprogramming the function of the AF-ON button, which stands for "Autofocus On". By default, the shutter release button is set to engage autofocus when half-pressed. However, by decoupling the autofocus function from the shutter release button and reassigning it to the AF-ON button, photographers can gain more control over when their camera focuses.

With back-button focus, photographers can lock focus independently of the shutter release. This means that they can focus on their subject using the AF-ON button and then recompose their image without needing to worry about the camera refocusing when they press the shutter release button to take the picture. This is especially useful in situations where the photographer wants to maintain the same focus point but adjust the framing of their image. For example, in portrait photography, a photographer might want to lock focus on their subject's eyes and then adjust the framing of the image to create an interesting off-center composition.

In addition, back-button focus simplifies the process of transitioning between shooting stationary subjects and moving subjects. With the default autofocus settings, photographers need to remember to switch from Single-Shot/One-Shot autofocus (AF-S) mode to AI Servo/Continuous Servo autofocus (AF-C) mode when their subject starts moving. With back-button focus, photographers can simply keep their camera in AF-C mode at all times. When they need to lock focus on a stationary subject, they can do so by releasing the AF-ON button, and when they need to track a moving subject, they can continuously focus by holding down the AF-ON button.

Overall, back-button focus provides photographers with more control over when their camera focuses and simplifies the process of adjusting focus and transitioning between shooting stationary and moving subjects.

It eliminates the need to switch between AF-C and AF-S modes

Back-button focus is a camera technique that separates focusing and shutter release to two separate buttons. It is a useful way to stop the camera’s autofocus system from getting continuously engaged when the shutter is released.

When you pick up a camera and half-depress the shutter release button, the focus system engages and tries to attain focus on your subject, which is the way most cameras are set up by default. With a bit more pressure applied to the shutter release button, the shutter trips and an image is captured. This process occurs regardless of the autofocus mode set up on the camera.

This essentially means that the single shutter release button is used for two different purposes – one to focus and one to take a picture. While doing this, if you apply a bit more pressure to the shutter release button than usual, you will ultimately end up taking unwanted images.

Back-button focus takes the autofocus function away from the shutter release button and re-assigns it to another button on the back of the camera. The biggest benefit of back-button focusing is the ability to shoot in AI-Servo / Continuous Servo (AF-C) mode with all the benefits of One-Shot / Single Servo (AF-S). Since the dedicated focusing button is only engaged when you need to focus, you can keep your finger off of it when you need to lock focus and simply keep on taking pictures.

By moving the focusing function to a dedicated button on the camera and using the shutter release button only to take pictures, you can greatly simplify this process. Any time you need to focus, refocus or continuously track the subject, you engage the focusing button. If you need to take a picture, you engage the shutter release button. There is no need to remember which focusing mode you are using, because you can always keep your camera in AF-C mode.

It's particularly useful for wildlife photography

Button cameras, or cameras that use back-button focus, are particularly useful for wildlife photography because they allow photographers to separate the focus and shutter functions. This means that photographers can focus on their subject and then recompose the shot without having to worry about the camera refocusing when they press the shutter button. This can be extremely helpful when photographing wildlife, as animals are often moving and may be difficult to keep in focus.

Additionally, back-button focus can provide more flexibility in composition, as photographers are not limited to placing their subject under one of the autofocus points. This can be especially useful when photographing wildlife, as it allows for more creative and dynamic compositions.

Another advantage of back-button focus is that it can make it easier to shoot with a tripod, which is often necessary for wildlife photography. With back-button focus, photographers can focus on the desired area of the scene and then adjust the camera position using the tripod without having to worry about the camera trying to refocus.

Furthermore, back-button focus can be beneficial when using manual focus, which may be necessary in low-light conditions or when the subject is hidden behind a complex foreground element. With back-button focus, the camera will not adjust the focus when the shutter button is pressed, allowing photographers to have more control over the focus.

Overall, back-button focus can provide several advantages for wildlife photography, including improved focus accuracy, compositional flexibility, and easier tripod shooting. It allows photographers to have more control over their focus and composition, which can be crucial when capturing fast-moving and unpredictable subjects like wildlife.

Frequently asked questions