jimfl938 Loc: Acworth, GA

I am having a lot of unnecessary trouble setting up BBF on my T7i. Any help will be appreciated.

Thanks, guys and gals.

Jimmy

"I complained because I had no shoes until I saw a man with no feet"

CHG_CANON Loc: the Windy City

Page 396 of your manual is where the C.Fn-12 options are explained. Option 1 equates to BBF when you set the AF setting to AI Servo. By selecting option 1 - to have the camera focus, hold down the '*' button on the back of the body with your thumb. To stop AF, lift your thumb from the same button.

bleirer

This seems to show you how. Says you have to be in a creative mode.

https://www.usa.canon.com/internet/portal/us/home/learn/education/topics/article/2019/february/back-button-autofocus-explained/back-button-autofocus-explained

Longshadow Loc: Audubon, PA, United States

Since I don't understand what "having trouble" implies,
if it's like my T1i, BBF does not work in "AUTO" mode if that is the problem.
AUTO mode reverts to a PHD camera.

amfoto1 Loc: San Jose, Calif. USA

Longshadow and bleirer are correct....To use BBF, first be sure you have the camera in one of the "Creative Zone" modes, as Canon calls them. Those are Av (aperture priority auto exposure), Tv (shutter priority AE), P (program AE), M (manual exposure) or M + Auto ISO (AE). BBF will not work in full "AUTO" or any of the "scene" modes (which Canon calls the "Basic Zone" of the mode dial... page 31 in the unabridged manual).

Chg_Canon is also correct that Custom Function 12 is used to set up BBF (page 396 in the unabridged manual). Switching the * button to BBF function is the method that's used on all the Canon cameras that don't have an "AF On" button, which was intro'd on the 40D if I recall correctly, but has never been incorporated into any of the Rebel series cameras. Over the yeas, I've used a number of Canon DSLRs and film cameras that req'd setting up the * button for BBF. Even 40D and 50D still needed the * button for BBF when using them with BG-E2 or BG-E2N battery grips, because those dated back to the 20D and were never redesigned to include an AF On button. Since the grip only had the * button, like the earlier cameras, when using BG-E2/E2N on the later cameras, it was most convenient to just keep using * button on them too, then set the AF On button to only give AE Lock.

However, I disagree about using Option 1 of C.Fn-12.

Yes, that will assign AF start and stop function to the * button, but it also will cause AE Lock every time it's pressed. Instead I recommend using Option 3, which leaves AE "unlocked".

Normally when it's not being used for BBF the * button provides AE Lock. That's well and good because you can simply not use it most of the time.

But once you switch that button to serve for BBF you'll use the * button very frequently, for practically every shot, and there are very many situations where simply you don't want AE Lock occurring too.

If you ever need AE Lock too, the easiest way is to simply switch the camera to M (without Auto ISO), then set your own ISO, shutter speed and aperture. This will give the same "exposure lock", while leaving BBF enabled. Otherwise, you'd have to go into the menu and either switch C.Fn to Option 0 (AE Lock but no BBF) or Option 1 (BBF & AE Lock).

Once you have BBF enabled, set the camera's focus mode to AI Servo and go to town. You can start AF any time you wish, simply by pressing * button with your thumb. To stop AF running (such as using focus and recompose technique), simply lift off the * button. This allows you to leave the camera in AI Servo mode all the time, ready to shoot regardless whether subjects are moving or standing still. You no longer need to stop shooting and switch modes depending upon whether the subject moves or not. (Noe: Don't use AI Focus at all: That's not really a focus mode. It's automation where the camera is supposed to determine whether or not the subject is moving and then use the correct mode. I tested years ago and found it slowed down AF and sometimes didn't choose correctly or failed to change modes when a subject stopped or started moving. Haven't use it since and I don't miss it. In fact, the most pro-oriented, top-of-the-line Canon cameras don't even have AI Focus... they only have One Shot and AI Servo.)

To someone who has never used it, BBF may seem strange at first. But it quickly becomes second nature for most people. Once you're comfortable with BBF, you can leave the camera in AI Servo mode all the time and be ready for anything.

The only "down side" to this is that in AI Servo mode there's no "Focus Confirmation". If you think about it, this makes sense. AI Servo is "continuous focus". It never stops and "locks" the way One Shot does. Since AI Servo continues to run and constantly update focus as long as you keep pressing the button, there's never anything for it to confirm! Some people find this disconcerting at first. But if you stick with it and learn to trust the AF system and yourself, you will find BBF gives you great control over AF. Of course, if you miss Focus Confirmation too much you can always switch back and do without BBF.

By the way, two other functions tied to the half-press of the shutter release button will continue to work the same even after BBF is set up. Half-press of the shutter button will still cause the camera's metering system to start taking readings and if your lens has Image Stabilization that will start running too. BBF only removes the AF start function from the shutter button. Both metering and IS also will start when ever you press the * button to activate the AF system, even if you haven't half-pressed the shutter button.

Finally, if you ever lend your camera to someone to use and they're unfamiliar with BBF, a quick and easy way to temporarily override it is to switch the camera to the full "AUTO" mode or one of the "scene" modes that's appropriate for what they'll be shooting.

Note: There are two different T7i manuals available to download online. The "BIM" or "basic instruction manual" is heavily abridged and shows multiple languages. The English section is about 227 pages. If a printed manual was provided with the camera it is probably this "basic" version. Supposedly to save paper and the environment, Canon in many cases now only provides the full and unabridged "IM" English version of manuals digitally on disk or as PDF downloads from their web sites. The full T7i manual (English) is 488 pages.... more than twice the size of the "basic" version's English section.

jimfl938 Loc: Acworth, GA

I will make just one thank you reply. All of you were a great help and I appreciate it very much. I am less dense now.