I wanted to share a documentary with you that’s just been posted to the Canon Professional Network site. It follows the legendary photographer Don McCullin, who traditionally has always shot on film, as he makes a transition to using the digital 5D Mk III. You can watch the film here (its around 27 mins long).
Interestingly, near the beginning the guy helping him mentions using the AF-ON button for focusing. Otherwise called back button focusing this is something I’ve been playing with of late and would heartily recommend it. Moving the focusing from the shutter button, disengages the metering, which happens as you half press the button, from the focusing. This means you can set the focus, recompose your shot, then shoot a well metered photo. I’ll admit there have been occasions recently where I’ve forgotten to focus because of this but I’m slowly learning and adapting my shooting style and for now think I will continue to use back button focusing. If you want more information on this then just do a search on Google and you’ll find loads of in depth articles covering this technique.