Do You 'Back Button' Autofocus?

[Derrel]

The AF-ON button is relatively "new" to Canon consumer d-slr bodies; earlier bodies in the xxD series, like the 10D and 20D had no AF-On button, but instead used the * button and a custom function setting in the menus to assign what Canon calls "back button focus"; in the consumer bodies, Canon introduced a dedicated labeled "AF-ON" button with the 30D or was it the 40D???

Nikon bodies vary in their controls; the "pro" body D1 and D2 series bodies had two buttons AF-ON and AE-AF lock located side by side, with a number of different functions possible to assign. On the D3 series, those two buttons have been re-located.

There are plusses and minuses to both systems; sometimes it's easier and better to separate the focusing acquisition from the shutter release action, while other times there's very little advantage. In long-lens, spot-focus work like baseball or high jump events where the peak of action will occur at a SPECIFIC location, it's often better to have the AF located on a thumb control, so you press the AF ON button with your thumb to activate the AF, get an AF lock, and then wait with the camera aimed at the target area on a monopod as the action approaches the exact spot where the AF has already been set to--like a slide into second base, or a throw to first base, or the high jumper as he clears the bar...

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[Andrew Boyd]

There are plusses and minuses to both systems; sometimes it's easier and better to separate the focusing acquisition from the shutter release action, while other times there's very little advantage. In long-lens, spot-focus work like baseball or high jump events where the peak of action will occur at a SPECIFIC location, it's often better to have the AF located on a thumb control, so you press the AF ON button with your thumb to activate the AF, get an AF lock, and then wait with the camera aimed at the target area on a monopod as the action approaches the exact spot where the AF has already been set to--like a slide into second base, or a throw to first base, or the high jumper as he clears the bar...

This is a great analogy and the message I was trying to get across in the original post
The BBAF gives you much, much more control over shooting/focusing in dynamic, fluid action situations...if all of your shooting is tabletop in the studio, then you probably don't need it.

Andrew
The Discerning Photographer

[mwcfarms]

The AF-ON button is relatively "new" to Canon consumer d-slr bodies; earlier bodies in the xxD series, like the 10D and 20D had no AF-On button, but instead used the * button and a custom function setting in the menus to assign what Canon calls "back button focus"; in the consumer bodies, Canon introduced a dedicated labeled "AF-ON" button with the 30D or was it the 40D???

Nikon bodies vary in their controls; the "pro" body D1 and D2 series bodies had two buttons AF-ON and AE-AF lock located side by side, with a number of different functions possible to assign. On the D3 series, those two buttons have been re-located.

There are plusses and minuses to both systems; sometimes it's easier and better to separate the focusing acquisition from the shutter release action, while other times there's very little advantage. In long-lens, spot-focus work like baseball or high jump events where the peak of action will occur at a SPECIFIC location, it's often better to have the AF located on a thumb control, so you press the AF ON button with your thumb to activate the AF, get an AF lock, and then wait with the camera aimed at the target area on a monopod as the action approaches the exact spot where the AF has already been set to--like a slide into second base, or a throw to first base, or the high jumper as he clears the bar...

yes I know this is an seriously old thread but I was wondering about what the benefits something like this would be for say portraits etc. Working on my focussing and been trolling out threads lol and this intrueges me so I need to ask the big guns about it.

[BKMOOD]

Funny this subject has come up, considering I just finished shooting a college basketball game about an hour ago. I use "rear button" or "back button" focusing mostly in sports photography.

There is too much movement amongst players going on to leave autofocusing to its own devices, as it is always hunting for something to focus on.

With rear button focusing, the camera begins and ends auto focusing when I tell it to. With rear (back) button focusing, I focus on what I want and stop if something like a ref or other player walks by and resume focusing when the coast is clear.

My photo keep rate doubled once I began using rear (back) button focusing. Outside of sports, I hardly ever use it. Once in a while, when I am trying to focus on something off center, I will use rear (back) button focusing.

[peacock]

I don't know about back button AF, because I always end up with my photos getting locked without my knowledge (because it also serves as a 'file lock' button when reviewing images). Maybe I'm doing something wrong?

Other than that, I do find it tremendously useful compared to the normal 'half-press' AF.

[gryphonslair99]

Did you ever learn how to 'back button' autofocus? Does your camera offer this option? Here's why this method is so clearly superior to shutter release focusing:
Quick Tip: Learn to Use Back-Button Autofocus
Andrew
The Discerning Photographer

Yes.

[nikole957]

I use back button on my 40D which is mainly used for sports and wildlife. On the 5DII I am in studio a lot and use a wireless radio release.

Im not a hundred percent on this in my head. You can have the rear autofocus button autofocus differantly than the shutter autofocus? Does both buttons have to AF the same way? I have done zero research on the matter and it itrigued me.