Back button focus is interesting - anyone using it?

http://www.learn.usa.canon.com/resou..._article.shtml

Basically the concept is simple:
1) leave your camera in AI servo full time
2) button on the back of camera is set to 'focus+set exposure'
3) shutter is set to 'set exposure and take picture'

The main benefit, as I see it:
once focus is locked, you can reframe/take as many pictures as you want without the camera trying to refocus. I quite like the idea of locking focus and taking as many pictures as I want without possibly changing focus.

It's esp. nice if focus wasn't easily achieved in the first place (shooting through windows/leaves),

Second benefit is basically you never have to change between 'one shot' and 'ai servo' anymore. You just tap the BBF button for one-shot.

You pretty much need to set a custom function for 'shutter focus' if you hand the camera to other people. Normal people would o@ at BBF.

I suppose the big negative would be if you are in servo/servoish mode, where your subject is constantly moving AND you want to keep changing other settings too. You can't hold down the BBF button and push another button at the same time after all.

I suppose most of the time, you'd just lock focus and then you can take as many pics as you want, with whatever settings.

I'll give it a spin this weekend, see how I like it. Not sure how much more annoying a press-press will be, compared to a half-press/full-press.

- Frank

 

I've used the AF-ON button on the back of the camera for a few years now. I don't keep the camera in AI Servo all the time though, it's mostly in One Shot.

It's to the point where I try to push that button on cameras that don't even have it and the half shutter press focus feels foreign to me.

Edit: You get used to it and don't even think about the dual button press anymore.

 

one downside of staying in AI-servo all the time is that the AF assist beam will not fire from your flash unit.

 

i used to do that too, but i stopped. mainly cause i dont do focus recompse anymore.