Some cameras have an alternative method for focusing – other than holding the shutter button part-way down. On my Canon 40D this is done through a button labeled AF-ON. The AF-ON button on Canon and Nikon DSLRs can serve a few functions depending on the options in your camera’s custom settings. Refer to your manual for how to set your preferred use of this button.
First, watch this video explaining the reasons to use this feature. He presents a good overview of the three auto-focus options (Single, Continuous, etc.) before describing the advantages of using the AF-ON feature.
VIDEO NOTES:
- This is part of a group of videos. Hit refresh (F5) if you get the wrong video.
- Intro lasts about 20 seconds
- Overview of AF Modes from 1:21 to 3:20
- AF-ON button explanation 3:24 to 6:25
- Set-up AF-ON button (Nikon cameras) 6:45 to 9:40
[youtube http://www.youtube.com/watch?v=FzqQskGoURE?list=UUhUi5Gm8w-S_d6dS31cFCnQ]