Getting my work out to the public, to share and learn

Back-Button Auto Focus

I changed the way I trigger the auto focus on my camera and it has stuck.

There is a technique of using a second button (other than the shutter release button) to trigger the autofocus and it is not new to the camera world.  Believe it or not the availability of this function on a camera body has been around since 1989 (Canon SLR film camera).  I on the other hand first heard of the technique and of others using it with great success though one of the many photography podcasts that I listen to about 8 months ago.  Their success was enough to convince me to give it a try.  It did take a while before I got used to it as the shutter button focusing was so engrained in my memories (both mental and physical), but now I would not switch back.  For me and how I take pictures it has meant I am “getting the shot” more often and by that I mean the focus is right where I wanted it.  The technique has helped me in three main areas.  With moving subjects where I have the camera set to AL focus or AL servo mode, I can keep that focus point trained on the subject and not have to worry about keeping the shutter only halfway pressed.  It has allowed for quicker locking of both AF and exposure, as now these are being controlled by two different buttons (exposure is still set when the shutter is halfway pressed). The last major benefit I have found is with my composition.  By allowing me to lock that focus, then composing and knowing it won’t change before or when I take the shot; I’m more relaxed with spending the time to compose (no more finger cramps).

The function of setting a back button is available on many brands and models of cameras, so if you have the option, give it a try, it just might surprise you too.

Nothing ventured, nothing gained.

Here is a link to a Canon article about using a back-button for auto focus –


One response

  1. Robert

    Nice summary about this very useful function 🙂

    June 1, 2011 at 6:31 pm

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