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Back Button Focus – Sharp Focus Photography Guide

Have you ever dialed in the focus perfectly, pressed the shutter button, and the focus automatically changed, creating an out-of-focus image?

Using back button focus, you’ll never have this problem again.

Back button focus ensures sharp focus, 100% of the time, ensuring precise control over focus, exposure, shutter speed, ISO, and depth of field, producing higher quality images.

Below, you’ll learn five, step by step, back button focus techniques, for sharp focus in any shooting scenario.

Back Button Focus – Why You Need It

Out of the box, cameras control autofocus using the shutter button, which also takes the image.

When the autofocus button and the shutter button are one and the same, the camera has to guess between two choices. 

Should it:

  1. Take the photo?
  2. Focus on the subject?

The camera’s guess is often incorrect leading to out-of-focus images & incorrect settings.

Moving the autofocus button to the back of the camera removes this guesswork giving the photographer complete control & sharper images on a consistent basis.

Now, the photographer can control focus with a single button and take the image with a single button.

Benefits of Back Button Focus

Each important camera setting should be controlled by a single button, no more.

This way the camera never has to guess why you’re pushing a specific button.

Here are the main benefits of back button focus. Each is described in more detail lower on this page.

  1. Photographer has complete control of focal point location and focus prior to taking the image.
  2. Photographer has complete control over metering prior to taking the image.
  3. Photographer has complete control over exposure triangle settings prior to taking the image.
  4. The camera never guesses what the photographer wants.
  5. Photographer has complete control over the camera & lens.

When the photographer wants to focus, they press the back button.

When the photographer wants to capture an image, they press the shutter button.

It’s that simple.

Problems with Shutter Button Autofocus

Here are some of the problems produced by having the autofocus button assigned to the shutter button.

These are the main reasons to start using back button focus.

Problem 1: Unwanted Change in Focal Point, Exposure Settings & Metering

Using the shutter button to focus often produces the incorrect focal point, exposure/image brightness, and shutter speed, rending the image useless.

Here’s an example:

After selecting the correct settings, f-stop, shutter speed, ISO, and focus, the photographer reviews the image, prior to pressing the shutter button.

When pressing the shutter button, the camera tries to refocus and meter the amount of light in the scene.

Although both tasks have already been accomplished by the photographer, the camera has no way of knowing this.

Without the photographer being able to review these newly selected settings, the camera captures the image.

Since the camera was guessing at the new settings, without the photographer’s final review, the image was out of focus with the incorrect focal point and exposure.

None of these problems exist using back button focus.

After selecting the correct focal point, using the back button, the photographer selects the exposure settings & presses the shutter button.

The shutter button takes the image, nothing more, nothing less.

The results are sharp focus and the correct exposure settings, consistently.

Problem 2: Delay in High-Speed Continuous Shooting

When the autofocus button and shutter button are one and the same the camera may not take the photo at the precise moment the shutter button is pressed.

At times, when the photographer wants to take a large number of photos, quickly, in sequence, as often happens in wildlife or nature photography, the camera may not take the image.

Instead of taking the image, the camera tries to refocus, delaying the image.

The photographer, in turn, misses the shot.

Here’s an example:

The photographer has selected the perfect focus, exposure settings and focal point within the scene, preparing to take an image of birds flying by very quickly.

  • The shutter button must take the image the instant it’s pressed or the birds will be gone.
  • The camera doesn’t know if the photographer is trying to take the image or focus on the birds.
  • The photographer knows he/she is ready to take the image but the camera does not.

The camera guesses and tries to focus on the birds, therefore it does not take the image the instant the shutter button is pressed.

It may try to refocus, for seconds, missing the shot entirely.

When holding the shutter button down to take a series of images, in quick succession, the camera may or may not try to refocus each time. It’s a guess!

  • The photographer knew the image was in focus and only wanted to capture the shot.
  • There was no way to communicate this to the camera so it guessed & tried to refocus.

By moving the autofocus button to the back button, the camera no longer delays or tries to focus when the shutter button is pressed.