John N Loc: HP14 3QF Stokenchurch, UK

I thought I had set BBF on my camera - and I have, but what I haven't managed to do is separate BBF from the shutter button.

I've arrived at the custom controls via. the C.Fn III (4) and the 'Q' screen and have followed the instructions as I see them, and I get BBF. But if I move the camera slightly it refocuses when I depress the shutter button.

What am I doing wrong, or what have I misinterpreted?

Dave327 Loc: Duluth, GA. USA

I do not own a 6D II. What mode are you in? On both my T6 & 77D the focus reverts back to the shutter if in are in auto (A).

jdubu Loc: San Jose, CA

I believe you have set BBF correctly, but have not disabled the shutter button auto focus to shutter activate only. It's a 2 step process, activate BBF and deactivate shutter button.

CHG_CANON Loc: the Windy City

Exactly. John, see page 497 of your EOS 6DII manual, where they have an example of changing to the shutter release to metering, the 2nd step of enabling BBF on this body.

John N Loc: HP14 3QF Stokenchurch, UK

Thanks, resolved (I think). Getting dark here and a hint of thunder but it seems O.K. indoors.

I've got a printed manual and I'm looking at page 497 but it doesn't read clearly to me. Guess that's my fringe dyslexia problem kicking in again. I can't find any reference to BBF in the manual, bit I know I didn't have this problem with my previous 60D - that was a cinch!

Once again thanks. Nighty Night!

CHG_CANON Loc: the Windy City

There's no such thing as "back button focus" in any camera model, ever. BBF a slang term. Rather, there are 'custom functions', where the English EOS 6DII explains on page 497 how to change the assigned function for the shutter release button by way of demonstrating how to change the assigned functions for eight of the external buttons on this camera model.

John N Loc: HP14 3QF Stokenchurch, UK

Correct. Nina Bailey in her pocketbook guide for the EOS 6D mkII (ISBN 978-1-912463-01-5) does say
'AF-ON BUTTON This is often called back button focussing...................'

amfoto1 Loc: San Jose, Calif. USA

What did you change when you went into C-Fn III Operation/Others, 4: Custom Controls?

Reading your description, it sounds as if you went into that C.Fn and looked at it, but didn't actually change anything.

Starting from the camera's shooting mode (not video mode), repeat that process of navigating through the menu to that C/Fn, which I'll call the main control customization screen

Once you are there you need to navigate to the shutter release button. Open that (press Set) and you'll see a screen labelled "Shutter Butt. Half Press", with three options below it. By default it's set to the one on the left with the icon labelled "AF". You need to navigate to the center, unlabelled icon and when you do will see a "Metering Start" description above it. Press "Set" again to confirm this selection. This will return you to the main control customization screen, where you should press the "Menu" button to exit and return to shooting mode.

What you're actually doing is removing the AF Start function from the Shutter Butt. Half Press.

The "AF On" button is already programmed to start and run AF, so you don't need to change anything with it. (By default, the camera is set up to start and run AF from both Shutter Butt. Half Press and from AF On button on the rear.)

Once you've made the above change, half pressing the shutter release button will still start the camera's metering system and, if your lens has it, activate Image Stabilization.

Pressing the AF On button will also start the camera's metering system and activate IS, as well as start and run AF.

Now set your camera's AF mode to AI Servo and you're all set. You can use AI Servo for both moving and stationary subjects, starting and stopping the AF system with BBF as you see fit, while continuing to use the Shutter Butt. to take shots. For example, if you are shooting a stationary subject and want to focus on them, then recompose the image, you can do so without first having to change focus mode or having to select different AF points. Just focus (using BBF), lift pressure off the AF On button to lock focus, then recompose freely and take your shot. Or, if the subject starts moving, you don't need to stop and change focus modes, can just start continuous focus by holding pressure on the back button.

Another benefit of this is that many zoom lenses today are "varifocal". That means they don't maintain focus when you adjust the focal length of the zoom. If you are using One Shot focus mode, you have to consciously stop focus, then restart it. However, since you are now using AI Servo most of the time... whether the subject is moving or not... and continuous focusing will automatically correct focus any time it's lost because of a varifocal type of zoom. (Varifocal design zooms are simpler and less expensive to produce, less "fiddly" to calibrate and keep calibrated, so have quietly become more popular among manufacturers. They probably figure autofocus that's found on almost all cameras and lenses today, makes up for the varifocal. And, it does. But only to a limited extent, unless you use a form of continuous focus like AI Servo.)

EDiT: In their manuals and camera menus, Canon doesn't call it "BBF" or "Back Button Focusing". They just refer to it one of many possible "customizations". I think this is what CHG_CANON was referring to in an earlier post. The "AF On" button is what you use to do BBF. The AF On button is already set up to do it. But, as I mentioned above, to truly "do BBF" you have to remove the "start/run AF" function from the Shutter Butt. Half Press, which in its default setup will also activate AF.

NOTE: I noticed in the user manual that setting the camera to video mode will negate the above change. Overlooked that earlier. I don't use my DLSRs to shoot video, but it might be important to some users. AFAIK, the BBF setup will only be cancelled during video mode... the camera will return to the above setup as soon as you switch back to still photography mode.

I've used BBF and AI Servo with various Canon SLRs and DSLRs for around twenty years. I also use as few AF points as possible, often only a single point. It's more work for me, but by doing these things I get a very high percentage of in-focus shots. Over the course of eight or nine hours, I shot around 4400 photos with a pair of 7D Mark II at a recent equestrian event (Hunter-Jumper show... lots of movement and action). During post-processing inspection of all the image in Lightroom, I "black flagged" around two dozen focus "misses", which I'd wager are mostly my mistakes (shooting too fast, forgetting to press the AF On button or pressing the wrong button, etc. ). I doubt many of those "misses" were the fault of the camera and lens.

Clapperboard

I was always envious of people with dyslexia. But then I thought it said they had SEXDAILY!
Apologies to all.

amfoto1 Loc: San Jose, Calif. USA

ROTFL!

John N Loc: HP14 3QF Stokenchurch, UK

Thanks all for some comprehensive replies and a laugh along the way.

Up and running on AF-ON (BBF) now.