Back-Button Auto Focus

As well as wildlife, I shoot a lot of sport. I've been pondering whether to set my camera (Canon 1D Mark III) to activate back-button AF. If you're not aware of this facility, it removes auto-focus from the shutter button and transfers it to a rear button which is operated with the right thumb. This is often set to the Auto Exposure (AE) Lock button (*). On my ID3, there's also an additional dedicated AF-ON button.

 

For those (like me) who are used to activating metering, auto-focus and the shutter with just the shutter release button, switching AF to a separate button may seem like an unnecessary complication. There are good reasons though, particularly when using focus tracking (AI Servo with Canon) mode.

 

Has anyone switched to back-button AF? It seems that most who try, never switch back. Just to make it even more complicated, there are several Custom Function options available when configuring the camera to back-button AF. I'd be interested to hear of peoples' views on this and on which function they use (and why).

 

NB: This facility is not available if the camera is used in full-auto or in one of the "picture icon" modes.

 

Many Thanks

 

Ed ...

Tags: AF, auto-focus, back-button

Views: 14

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Permalink Reply by Garry Bowden on October 25, 2010 at 10:45
Hi Ed,

I use Nikon, but they also have the 'back button' af facility. I started to use this about 4 years ago and would never go back to using the shutter release for focusing. It's a fantastic way of focusing and very versatile. Who needs to use the focus lock button when the subject is off centre or outside the focus points. Just use the back button to focus, let go of it and re-compose, job done. What about another player getting in the way of the player you are focused on? just let go of the focus button and wait until they are gone and the original player is still in focus, push the back button again and you are following them.
I found that I needed to give it some time to get used to it, but it will soon become second nature. Can be a tad confusing at first to push 2 buttons to get a piccie, but once you have mastered it you will never go back.

Good luck

Garry
Permalink Reply by Ian Cook on October 25, 2010 at 10:49
Hi Ed,

I've been using backbutton focussing since i had my 20d many years ago now. Will have to have a look through my custom functions and see what they are set to a bit later when im not supposed to be working ! lol

I find it natural now, some people find it very difficult to deal with, and give up, before giving it a real chance. If you persevere with it though, it does make a huge difference, and my cameras are nearly always in AI Servo :)

Ian
Permalink Reply by Ed Phillips on October 25, 2010 at 11:08
Thanks Guys

My ID3 is almost always in AI Servo mode too. With BBAF, it seems to have the added benefit of providing one-shot functionality by just releasing the back-button!

I'm still not sure wich Custom Function to use:

- Metering Start/Meter+AF Start or ...
- AE Lock/Metering + AF Start

Would be interested to see your settings Ian (once you get a minute!). Presumably these (or similar) options are avialable on the Nikon Garry.
Permalink Reply by Ed Phillips on October 25, 2010 at 11:19
I'd also be interested in hearing what Custom Functions you use for Auto Focus/Drive Ian ...
Permalink Reply by Peter Walkden on October 25, 2010 at 12:57
I switched to using the AF via the back button when someone said it was possible on my 40D, and have set it up since on my newer 50D. I find it second nature now and miss it when using another camera not configured this way.

For bird photography it is very handy, especially if the subject isn't out in the open and the focus could be taken away by objects between me and it. I use the cameras in AV mode, so it's available here.

It does take a little getting used to, and can feel slightly alien to start with, but I'd not go back now.
Permalink Reply by Patrick Fox on October 25, 2010 at 15:24
I must give this a go. It sounds like a more controllable form of AF. Is it easy to set up on a 50D? I'd also like to be able to revert easily for those times when my daughter borrows my camera rather than expect her to master it too.
Permalink Reply by Ed Phillips on October 25, 2010 at 16:11
It will be easy to set up Patrick. Just involves setting the appropriate Custom Function.

I think that the easiest way to cancel it (when lending the camera), is to put the camera into Full-Auto mode. This will though, cancel some other facilities (like RAW shooting); depending on the camera.
Permalink Reply by Paul Gregory on October 25, 2010 at 16:42
Made the move years ago and never looked back. It's the first setting I do when getting a new camera for the reasons others have already mentioned.
Permalink Reply by Ed Phillips on October 25, 2010 at 17:27
What actual Function setting have you chosen on your 1D4 Paul?
Permalink Reply by Paul A King on November 24, 2010 at 18:07
No point saying it is brilliant you have all said it, but for my two pennath (Nikon) BBAF is such a bonus that I have it set in all but the landscape functions/memory banks.
In fact have not long ago starting to use it in the auto sensor lock for BIF and find it works a real treat, once you get used to the sensors lighting up all over the place!!! (D300 in case you wondered, will do tha same when the new camera arrives)

So basically if you do not use it give it go don't think you will regret it..

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