Essential Photography: Back Button Focus
Cormorant Fisherman on traditional bamboo raft at twilight, Li River, Xingping, People’s Republic of China
By default, almost every camera arrives from the factory with two important functions assigned to one big conspicuous button: the shutter release. It’s conveniently located where the right index finger would rest when holding the camera comfortably in your hands. This button will engage autofocus when pressed halfway and fire the camera when fully depressed.
By configuring your camera for back button focus, you separate these two functions by 1) disabling autofocus on the shutter release button – perhaps the most important part of adopting back button focus – and 2) reassigning autofocus to a button on the back of the camera where the thumb comfortably rests. So now the shutter release button ONLY fires the camera when depressed by your index finger and no longer starts autofocus. The autofocus is all in your thumb.
Every camera is different, but they all should allow you to disengage autofocus from the shutter release button and reassign it to another button on the rear of the camera, preferably near your thumb. Consult your camera’s manual to find out now.
At first glance, it might seem like a more complicated way of doing things, but it’s not. After a minor adjustment period, it will soon feel as natural as the default set up, maybe more so. It’s just so easy; thumb focus, finger capture. There are many things we do in everyday life which involves using the thumb and index finger simultaneously. And some of these things are actually good.
I find back button focus most useful for rapidly-changing scenes or quick-moving subjects commonly found in street and wildlife photography. You now have the ability to autofocus and recompose the scene without having the camera refocus again when you take an image. Just focus on your subject, make a slight change to the composition by moving the camera while your subject stays in focus, and then shoot. Pressing the shutter release only fires the camera. It doesn’t activate autofocus again.
Red-eyed tree frog, Agalychnis callidryas, Monkey River, Toledo District, Belize.
The frog photograph above is a superb example of when back button focus will serve you well. Place one of the autofocus points over the frog’s red eye (you always want an animal or person’s eye to be tack sharp, even if other parts of the subject are not) and focus using your thumb on the designated autofocus button on the back of the camera. Then take your thumb off the autofocus button (essentially locking in focus) and quickly recompose. In this case, using the green branch from the bottom left corner to lead the eye into the scene. Take the shot with your index finger on the shutter release. Even though the focus indicator is no longer on the frog’s eye after moving the camera, the focus won’t change because that function has been removed from the shutter release.
As I said, I find this way of focusing most valuable when I’m doing wildlife photography but I use it for any scene where I’m using autofocus. Focusing with my thumb is now a grooved habit that has taken quite a bit of time of set in. The middle of an expensive Africa safari is not a good time to experiment with back button focus if you’ve never used it before. Under stressful situations (a lion stalking your safari vehicle with a setting sun over it’s left shoulder, as an example) you will defer to the familiar without even thinking and this shot of a lifetime will be out-of-focus because you assumed it was focusing with the shutter release button. Practice, practice, practice. Practice so much that it becomes second nature and you don’t even have to think about it.
Love love love this!! -I need these instructions.. thank you for your wonderful blogs and for teaching us not only basics but practical things about photography to get out there and apply.. You’re a wonderful teacher & we are SO blessed by your generosity and time.. Mr. Bernabe.. thank you!
This is a fantastic write up. This is SOOOO helpful!! Your suggesations are always so helpful. Thank you so much Richard! I am so looking forward to taking one of your workshops!!
Hi, Nice article.Keep sharing.
This is a great article which is easy to understand. Thanks a lot for sharing this with us.
Use “continuous” AF in addition to the back button focusing. While you hold the button focus will follow the subject. Good for sports and macro shots. On my Nikon it’s called “AF-C”.
Use AF tracking mode. Here is how it works on my Nikon: the focus point is always in the center. Focus on subject, hold focus button and recompose. Focus point will follow subject as you recompose. Sure, a DSLR has limitations (small AF area) compared to MILC, but it’s often good enough. Advantage: no need to move the AF point with buttons / joystick.
Set AE-lock to shutter release button half pressed. Now you can lock exposure independently of focus and final composition. Requires some finger acrobatics, though. And is only necessary in complicated lighting conditions. But is very useful in some cases.
I don’t, as I forget my camera is on back button focus and end up taking out-of-focus shots. Even after two-ish weeks of using my camera daily with back button focus.
Nice tip! Have you ever described how you’ve customized your other programmable buttons/dials and why? If so, please link.
Hi, awesome article on back button focus.This is something I can use! Thanks For sharing.
My Canon 750D doesn’t have the facility for back button af, but my new 77D does( when I get it)!
Wow, Your ideas is very good for new photograper like, me. I am freelance photographer in Singapore.
Your post is amazing, It is very helpful for new photographer like me.
Everything you do is awesome!
Thanks for sharing. I switched to back button focus about a year ago and my in-focus shot percentage has increased dramatically. Oh and I switched to Sony 🙂
Once I trained myself to use AF-On years ago, I’ve never looked back. I can get precise focus while composing a boudoir shot, then recompose and get exactly what I need! This is such a helpful tip… thanks for bringing awareness to this wonderful (semi-overlooked) feature.
This is a great blog!!! Thanks for sharing this information with us!
Back button focus most useful for rapidly-changing scenes or quick-moving subjects that is found in the street and wildlife photography. Thanks for sharing this information. It is really helpful.
I love this blog. Your explanation is the most clear of anything I have read on back focus. I really appreciate the information — and particularly as explained so clearly and crisply. By the way, I would be in seventh heaven to get a photo of a red-eye tree frog like yours!! It is gorgeous.
If I set up my back button to go from Al Servo to One shot and vice versa on my Canon 7D Mk 2 wouldn’t this do the same as above and be a little simpler i.e. you still focus off the front button. Also you would get a bleep (if you wanted it) when focus has been achieved in singe shot.
I think a lot of the other higher end Canon cameras have this function as well
Your article is very good and the image is very beautiful, I really like that green frog.
Yes this is a great idea! I will start implementing that.
Read many posts (and watched videos) on backbutton focus technique. Yours is most simplistic that is a reference, and I would never have to read up any further material on the subject. Thanks for sharing!
Love that first shot! Amazing!