Back-Button AF

Started Dec 12, 2013 | Discussions
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Missy Stone Forum Member • Posts: 50
Back-Button AF

I have a 5D3. I like using back button AF. I have set up AF-ON to "Metering and AF start".

My question is, should I remove AF from the Shutter Button?

The canon video tutorial  suggested that I set the Shutter Button to either "Metering Start" or "AE Lock".

I sort of didn't want to do that because I wanted to be able to still use the Shutter Button for AF so that it won't get too complicated if I lent the camera to someone else to have them take a picture of me.

Is there a problem with not disabling the AF from the Shutter Button if I already enabled it on the AF-ON back button?

Thanks!

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Canon EOS 5D Mark III Canon EF 50mm f/1.4 USM Canon EF 70-200mm f/2.8L IS USM Canon EF 24-105mm f/4L IS USM
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AHWest Forum Member • Posts: 69
Re: Back-Button AF

I had the same thought. I only would use back button AF when doing action photos, so I only set it up to work that way in my C3 settings, which has minimum shutter speeds, and AF settings that match that kind of shooting. Switch the setting back to P, TV, etc, and focus is back on the shutter.

But I need to remember to use the back button AF next time I switch to C3.

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Pete512
Pete512 Forum Member • Posts: 66
Re: Back-Button AF
1

The purpose of using back-button focusing is to take the focusing function off the shutter button, not to give you another button to focus with.

The main use is in focus and recompose situation. Once you have focused with the af-on button, you don't want the camera to refocus when you hit the shutter button.  You can the place the subject anywhere in the frame and keep shooting the shutter button, and not have the camera refocus each time you shoot. If the subject distance changes, then just point the focus point at the subject and a quick jab at the af-on button, and you're good to go again.

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Jimmy K.
Jimmy K. Contributing Member • Posts: 715
Re: Back-Button AF

Missy: you should read this http://www.learn.usa.canon.com/resources/articles/2011/backbutton_af_article.htmlp

As Pete mentioned, it wouldn't make sense to have both buttons work as AF. I don't have my camera in front of me, but I don't think the camera will allow you to set it like that.

What you could do is this.

  • Shutter: Metering + AF Start
  • Back Button: AF Stop

"AF is still at shutter button. Pressing the rear button will actually LOCK the focus; potentially useful if you shoot a lot of moving subjects in AI Servo AF and prefer to activate AF with a conventional half-press of shutter button. Focus is unlocked by removing thumb from back-button."

I don't use it that way. I use this:

  • Shutter: Metering start
  • Back Button: Metering + AF start
KatManDEW Senior Member • Posts: 1,896
Re: Back-Button AF

Missy Stone wrote:

I have a 5D3. I like using back button AF. I have set up AF-ON to "Metering and AF start".

My question is, should I remove AF from the Shutter Button?

The canon video tutorial  suggested that I set the Shutter Button to either "Metering Start" or "AE Lock".

I sort of didn't want to do that because I wanted to be able to still use the Shutter Button for AF so that it won't get too complicated if I lent the camera to someone else to have them take a picture of me.

Is there a problem with not disabling the AF from the Shutter Button if I already enabled it on the AF-ON back button?

Thanks!

The other advantage of taking AF off the shutter button is so that full time manual focus lenses do not refocus when you take the shot, after using the full time manual focus. Near as I can tell, full time manual focus is worthless if you leave AF on the shutter button...

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beppe_it Junior Member • Posts: 34
Re: Back-Button AF

that's the way it is meant to be used.

once I started to be used I love it. if I hand the camera to someone else (my wife) I put in auto ;))

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canon-ista

Ecorone Regular Member • Posts: 322
Re: Back-Button AF

I used to use Back-Button AF exclusively on my 40D and that's the way I used to shoot the 5D3 initially, but I've been doing so less and less lately.

When I still use it:

1) In situations where I focus-recompose a lot.

2) In situations where I am continually tracking action (i.e. dance competition, sporting events), I find it easier to mash down the AF-on button than half-pressing the shutter release for extended periods of time.

Why I don't use it on day-to-day basis anymore:

1) I've set my DOF preview button on the right side of the lens to toggle between AI-Servo and One-Shot. My 5D3 is normally set to AI-Servo so it can track motion (my primary subject are my kids and they're almost always in motion). When I want to focus on something that doesn't move, I push the DOF button with the ring finger on my right hand and presto, I'm on one-shot mode and focus-recomposing is enabled without any menu-diving of any sort.

2) I got tired of all the out of focus shots whenever I handed the camera out to other people, with BBF enabled. And I don't like the results I get when the camera is on Auto.

3) With the 5D3's excellent array of AF points, my need for Focus-recompose is greatly reduced.

Hope this helps.

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shawn in ak Regular Member • Posts: 206
Re: Back-Button AF

I like having the option saved under one of my custom function settings on my 6D. It allows me to quickly change back and forth if the situation warrants it.

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NancyP Veteran Member • Posts: 5,320
Re: Back-Button AF

I use the MF/AF switch on the lens when shooting manual.

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NancyP

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Missy Stone OP Forum Member • Posts: 50
Re: Back-Button AF

This is a great idea! I'll use the AF-ON the way it was meant to be used in my custom function and then switch it to auto mode when I give it to someone else.

Thanks for all the reply.

beppe_it wrote:

that's the way it is meant to be used.

once I started to be used I love it. if I hand the camera to someone else (my wife) I put in auto ;))

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canon-ista

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