Have you ever dialed in the focus perfectly, pressed the shutter button, and the focus automatically changed, creating an out-of-focus image? If you have the auto-focus linked to the shutter release, then there is a good chance this can happen. In my humble opinion, if you use 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 and ISO along with depth of field. producing higher quality images.

Why to use Back Button Focus

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

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.

I have found that using the AF-ON button for back button focus has been much more reliable for capturing sharp images consistently and has over time improved my keeper rate. Try this simple technique to see if it right for you. I would love to hear your comments below.