November 27th, 2015
Photo Tip | Ryan Craig Follow The Light Finalist Teaches Techniques for Toggling Auto-Focus
Name: Ryan “Chachi” Craig
Home: Santa Cruz, Ca
Photog Influences: Chris Van Lennup, Nelly, Corey Wilson, Burky, Aaron Chang
Daily Driver: Canon 7D
Back button auto-focus is your friend. I’m sure at this point we all know that on a majority of digital SLR cameras – you have two different buttons to press to activate the auto-focus. The shutter button when pressed half way and the button on the back of your camera named AF-On (I’m referring to Canon DSLRs).
What I didn’t completely understand is the amount of focus-point control you have when you turn off the auto-focus on the shutter button. You can scroll through the menu on your camera and change what button activates your auto-focus. Go to the auto-focus section of your menu and change your AE lock. Make the back button (AF-On) the only button that controls the AF and have the shutter button only control the release of the shutter.
What this allows is the option to focus an image using the back button AF and then recompose the shot without having the camera try to focus again when you click the shutter. This is especially important when your camera is in a housing and you might not have the option to change you focus points.
An example would be: you’re shooting a wave in the distance and there is a nice bluff behind it. You want to compose the shot with the wave on the bottom third of the frame and the bluff taking up the top two-thirds.
Using back button auto-focus you can aim your focus point(s) at the wave, ensuring that it is in focus, then recompose you framing to include the bluff and push the shutter without the camera trying to refocus the image. This allows for complete control of your framing and thus, maximizing you compositional eye.