Back button focusing - guidance sought

[davidedric]

I know this has been discussed before (please point me to another thread if what I ask is covered there), and it is widely said to be a good thing, but I am not quite getting my head around what settings to use.

Shooting wildlife. Not BIF (I try, but I think that is another story). Mostly biggish and slow moving animals and birds.

I have a Canaon 600D/Rebel T3i. A I understand it, I can have
0 - the half press set AF and the back button to lock AE,
1 - the half press set AE lock, and the back button set to AF,
2 - the half press set to AF and the back button set to AF lock, no AE lock
3 - the half press set to AE, the back button set to AF. no AE lock

My most frequent shooting is single shot, autofocus on single shot, centre focus point (the only cross-point) selected (I want focus on the exact right spot on the animal), evaluative metering. Technique is focus with half press, recompose and shoot. I can't see what back button focus would gain me there, I assume that I would set the back button to focus and shoot as normal - but maybe the point is to get used to using it all the time?

I assume that if an animal is moving or might move then I think should switch the autofocus to "AI Servo". In this case I guess that I have to keep the active focus point on the animal (or maybe I should activate the other focus points), but I think I could also do this with position 0 selected, the default.

I know I must be missing something, but how and when would you deploy back button AF?

Thanks,

Dave

[WillN]

Back button focussing is a great technique for wildlife photographers. I use it, and I wish I had switched sooner!

In essence, it allows you to have the benefits of manual focus, One-Shot, and AI Servo all in one mode without switching anything. By separating the shutter from the focus, you can independently control both.

There's more information in this guide about back button focussing.

[DanK]

I use back button focusing most of the time. the simple reason is control. I like to decide for myself when I want the camera to use AF, so I don't want AF on the shutter button. I occasionally change in back when I know I won't want to stop the camera from focusing.

Re the particular settings: the menus are different for different Canon cameras, and I am not familiar with the T3i.

[davidedric]

Thanks. I had read that article, and got more confused:

Whilst photographing this great grey owl perched in the tree, I was using back button focussing. I pointed the chosen focal point (the centre point, as it is most accurate) at the owl and pressed AF-On to focus. Then, I was able to recompose the shot and press the shutter to take the image. All the time in AF-C mode!

I've had to go back and try again. Now I realise that the first step is to press AND RELEASE the AF-On button. I had been keeping it pressed, which just means the continuous focus kicks in.

Cheers,

Dave

[WillN]

Thanks. I had read that article, and got more confused:



I've had to go back and try again. Now I realise that the first step is to press AND RELEASE the AF-On button. I had been keeping it pressed, which just means the continuous focus kicks in.

Cheers,

Dave

I see! I will amend that sentence to help clarify it for people.

Yes, you press to focus and release to disengage focus. Then you can recompose happily and shoot away.
Keep it pressed simultaneously with the shutter pressed if you wish the take images whilst continually focussing (eg BIF).

[davidedric]

Thanks, Will, I hadn't realised you are the author

Fantastic photos of the great grey owl - makes any of my modest efforts look modest indeed. I'm heading back to read your other tutorials.

I am off to Tanzania for a couple of weeks this Sunday, so I'll see what I can come back with.

Dave

[NorthernFocus]

I think you are overthinking the whole thing. Focus with thumb, shoot with finger. No want no focus, lift thumb off button.

One of the good things about BBF is the simplicity. You don't need to worry about single focus vs continuous servo etc. Set it on continuous and leave it. Single focus situation? Focus and lift your thumb off the button. Voila.

[davidedric]

Thanks guys,

I've got it now It just takes a bit longer than it used to

Dave

[NorthernFocus]

The harder part is the eye/hand coordination after many years of doing it the other way. I'd recommend get out and shoot a bit every day and get used to it before you try to shoot anything important. But as others have said once you finally make the switch it's great.

[WillN]

Thanks, Will, I hadn't realised you are the author

Fantastic photos of the great grey owl - makes any of my modest efforts look modest indeed. I'm heading back to read your other tutorials.

I am off to Tanzania for a couple of weeks this Sunday, so I'll see what I can come back with.

Dave

Awesome!

Yeah I saw that we were getting quite a few hits through, so I checked out the website and I think it's a nifty forum!

Just remember that now you have BBF, when you press the shutter it no longer guarantees a focussed image!

[Manfred M]

I decided to try BBF a few months ago. I've set the back button to continuous focus mode and disconnected the shutter release from the autofocus functionality. I found that I really like this configuration for street photography as I primarily use a focus / recompose / shoot workflow; I guess this genre has a lot of similarities to wildlife photography, as the subject often does not hold still.

It's more of a pain (although a small one) when shooting landscapes and architecture. My other cameras are still configured without BBF, so I do screw up the occasional shot when switching to a different camera.

[dje]

Dave I have the same camera as you and am a recent convert to BBF. I use setting 1.

I have been thinking about using it for some time but it was only on our recent trip to Europe that I decided to give it a go. I was originally concerned that I would forget the focus step sometimes, particularly if I was in a hurry to get a shot but this concern proved to be unfounded and I don't think I missed one shot by forgetting to focus. It just becomes part of your routine after a while.

I don't think I'll go back to the old method. I just like to have the freedom to focus on what I want and then re-compose without worrying about the effect on exposure.

The only negative is if you give the camera to someone else to use temporarily (eg to take a photo of you and your better half).

Dave

[Mark von Kanel]

This thread has inspired me to try this, ive heard lots of peeps talking about bbf but never really looked into it nice site will. thanks all

[Glenn NK]

Once I learned about BBF (eight years go), I tried it, liked, and both bodies are set that way and will not be changed.

Glenn

[WillN]

Dave I have the same camera as you and am a recent convert to BBF. I use setting 1.

I have been thinking about using it for some time but it was only on our recent trip to Europe that I decided to give it a go. I was originally concerned that I would forget the focus step sometimes, particularly if I was in a hurry to get a shot but this concern proved to be unfounded and I don't think I missed one shot by forgetting to focus. It just becomes part of your routine after a while.

I don't think I'll go back to the old method. I just like to have the freedom to focus on what I want and then re-compose without worrying about the effect on exposure.

The only negative is if you give the camera to someone else to use temporarily (eg to take a photo of you and your better half).

Dave

I made the error of giving my camera to someone in the Himalayas, whilst set to BBF, to get a photo of me and my friend in front of a mountain range. The result? OOF memories. Luckily I have others that are in focus !!

[Dukatum]

I tried switching to BBF a couple of times with my Nikon D7000. I use my left eye for the view finder and wear glasses, and means that when I am using BBF with the AE-L button it's pretty uncomfortable.
I either have to pull my eye away a bit to create space for my thumb, or I'm squeezing the thumb in and each time I press the button but then I find myself moving the camera slightly each time I press the button.

[jprzybyla]

Cannon shooters went to Back Button Focus to equal Nikon's AF-A focus mode. Nikon's AF-A focus mode uses Single Focus Mode if the subject is stationary and switches to Continuous Focus Mode if the subject is moving (bird in flight etc.) Cannon cameras with Back Button Focus set and the focus mode set to continuous focusing is almost the same as Nikon's AF-A. Press and release the back button after acquiring focus locks the focus for stationary subjects and allows recomposing the image. Hold down the back button and the focusing will be continuous for moving subjects.

[inkista]

Cannon shooters went to Back Button Focus to equal Nikon's AF-A focus mode. Nikon's AF-A focus mode uses Single Focus Mode if the subject is stationary and switches to Continuous Focus Mode if the subject is moving (bird in flight etc.)

Er, no, not imo. AF-A is more like Canon's AI-Focus mode which switches between One Shot and AI-Servo. AF-S is like Canon's One Shot, and AF-C is like Canon's AI-Servo.

Back-button is not about being in a tracking AF mode vs. stationary subject AF mode; it's about precisely controlling when the camera either begins/ends searching for focus. That's why Nikon cameras do back-button, too.

[DanK]

I think this discussion may be complicating things for some readers. AFAIK, choosing which button to use for AF has nothing to do with the selection of an AF mode, such as single shot or servo. It simply changes which button triggers whichever mode you have selected. The main difference is that back button focusing gives you more control over when the AF of whatever mode is activated. E.g., if you have lenses with full time manual focusing, you can focus manually without worrying about the shutter triggering AF. Ditto if you use movement of the camera to focus in macro.

[NorthernFocus]

I think you are overthinking the whole thing. Focus with thumb, shoot with finger. No want no focus, lift thumb off button. ....

Or am I just a simpleton?