Back Button Focusing: Why should I use it?

Back Button FocusingMost digital cameras auto focus when the shutter button is pressed half way down, taking a picture when the button is fully pressed. When using back button focus, control of the focus function is moved away from the shutter button and to a button on the back of the camera (no one said the reason for using a particular name had to be complicated).


Why Should I use Back Button Focusing?


Now that you know what back button focusing is you are probably wondering why you would use it instead of the standard focusing option on your digital camera. The normal focusing by the shutter button certainly seems to be easier on the face of it, one button/finger controls both the focusing and picture taking, and holding the shutter button down allows you to lock the focus in place.

However there are some strong arguments as to why you should use back button focusing. The best reason I can suggest to you is for photographing action scenes. When using the standard focusing method on your camera the auto focus is completed once you then have to hold the shutter button down to get the camera to keep focusing as the subject moves. The problem is it can be hard to tell if the shutter button is half pressed or not. Plus if you accidentally press down to hard you run the risk of taking a shot too early.

The other risk with standard focusing when taking action shots is blurred shots. It’s a naturally tendency to lift the finger slightly before pressing down on the shutter button. So if you are holding the shutter button down to keep the camera focusing, you then release the button before pressing down an the subject moves nearer you end up with them slightly out of focus. With back button focusing you can hold the back button fully down while pressing the shutter button, removing this risk.

How do I enable back button focusing?


Obviously this can vary depending on the make of camera and even from model to model.

Canon where the first manufacture to implement back button focusing and have now made it available in all their models for nearly the last 10 years.  The only thing to remember is that back button focusing is only available in creative modes (i.e. shutter priority, aperture priority, program or manual) if you are in the “green zone” (i.e. fully automatic) then back button focusing will not work. The following is a list of the menu options used on a number of canon models to enable back button focusing:

  • EOS Rebel T3: C.Fn 7 (option 1 or 3)
  • EOS Rebel T3i: C.Fn 9 (option 1 or 3)
  • EOS Rebel T4i: C.Fn 6 (option 1 or 3)
  • EOS 60D: C.Fn IV-1 (option 1, 2, 3, or 4)
  • EOS 7D: C.Fn IV-1 (Custom Controls — Shutter, AF-ON, AEL buttons)
  • EOS 6D: C.Fn III-5 (Custom Controls — Shutter, AF-ON, AEL buttons)
  • EOS 5D Mark II: C.Fn IV-1 (option 2 or 3)
  • EOS 5D Mark III: C.Fn menu screen 2 (Custom Controls — Shutter, AF-ON, AEL buttons)
  • EOS-1D X: C.Fn menu screen 5 (Custom Controls — Shutter, AF-ON, AEL buttons)

The menu options on Nikon cameras vary a little more but they should be something like:

Step 1: Go into your custom settings menu

Step 2: Select A (autofocus)

Step 3: Select A5 (AF Activation)

Step 4: Choose AF-ON only

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