The AF-ON button on the 7D

Here there,i am a little confused right now,

What is the Advantage of seperating the AF and the Metering from the Shutter release Button and placing the AF on the AF-ON button??

I have had some time at the race track,got good shots with both the metering and AF on the Shutter release.
So whats the catch? i am always eager and willing to learn to make better pics,
thanks for your inputs

http://www.usa.canon.c​om …ArticleAct&arti​cleID=2286

With AF on the AF-ON button and AI SERVO enabled you have ONE SHOT capability (a quick blip of the AF-ON button) or AI SERVO capability (constant pressure on the AF-ON button) without having to switch modes.

i sometimes use it to prefocus, i lock focus on something distant and when my subject passes that item i take a picture. i wouldnt recommend that though if youre shooting something like a 1.2 lens.

jeree wrote in post #10370584
are you mainly using for video?

Hi no i have never used the Video and i don`t intend to use it in near future,i mainly use it for Motorsports,scoccer,po​rtriats and so on

The biggest thing for me is being able to focus without accidentally snapping a shot prematurely. Plus, if I'm trying to meter off of a portion of the frame outside of where I want my focus to be it's nicer to have those functions separate.

I just feel like I have more control over when I shoot when I don't have to futz with half-press vs full press of one button; with them separate I can simply press the release button when I'm ready.

for me I love it because once I get my focus I can take as many pictures as I want and change metering/settings etc without the camera changing and struggling to get focus every single time, Once I get it, until I press the button again it doesn't move

thank you all for the input,i guess i will give it a try if i make it to the track next weekend

Foil wrote in post #10370603
Hi no i have never used the Video and i don`t intend to use it in near future,i mainly use it for Motorsports,scoccer,po​rtriats and so on

Picture this: you're shooting soccer. You're in AI Servo mode. You half-press the shutter to lock focus (and metering) on a player as he's running up the field. Just as you're about to fire of a couple of shots, the sun pops out from behind a cloud, and bingo, your shots are all overexposed. Why? Because you locked metering as well as focus. If you'd used the AF button, that wouldn't have happened.

Yes, Foil, try it. The ability to meter one part of a picture and to focus (and often to stop focusing) on something else is a powerful tool for creative use of both focus and exposure control. Once you learn to use it, you will never go back to one button for both.

rral22 wrote in post #10371445
Once you learn to use it, you will never go back to one button for both.

But I did!

I don't like the two button approach, didn't suit my style and way of working at all - I have the AF-On button set to lock AF, but that's on 1 series bodies, don't know if others can do that.

AdamC wrote in post #10370716
Picture this: you're shooting soccer. You're in AI Servo mode. You half-press the shutter to lock focus (and metering) on a player as he's running up the field. Just as you're about to fire of a couple of shots, the sun pops out from behind a cloud, and bingo, your shots are all overexposed. Why? Because you locked metering as well as focus. If you'd used the AF button, that wouldn't have happened.

This is incorrect, at least for the 7D. The AF On button starts AF and metering, just as pressing the shutter release halfway does. There is literally no difference besides removing 2/3rds of the functionality of the shutter release unless you replace the half push with another function like exposure lock.

I thought you could set it any way you want? Pg. 218 in the manual. What I noticed with our wedding photographer is that he would lock focus, then release the shutter at calculated moments. Rather than locking focus and blindly shooting/bursting away.

IUnknown wrote in post #10372080
I thought you could set it any way you want? Pg. 218 in the manual. What I noticed with our wedding photographer is that he would lock focus, then release the shutter at calculated moments. Rather than locking focus and blindly shooting/bursting away.

He's talking about the default setting, straight-out-of-box.

At first I found it odd to use the back button but I use it all the time now and my miss focusing shots have gone down as well.