One of the most frequent questions I have received in the last month has been about back button focus and how to use it on Canon and Nikon DSLR cameras. In this article you'll learn what back button focusing is, and how to back button focus for Canon and Nikon cameras.
What is back button focusing?
The camera usually focuses when the shutter button is pressed half way down, and then the photographer takes the picture when the button is pressed in fully. Back button autfocus makes it so the shutter button doesn't control the focus activation at all, but instead assigns another button on the back of the camera (hence the name) to activate focusing on the camera.
What is the purpose of back button focus?
The best way to explain the benefits of back button focusing is through two examples.
Example number one
First, suppose you are shooting portraits. The person who you are shooting is standing still and you want to take several different shots of the person. You take your first shot, and then change your composition and need to move your focus point to be on the person's eye. If your camera has 40+ focus points like many DSLRs do, you have to use the four-way selector to tediously move the focus point to the correct spot, focus, and then take the photo. How annoying!
You can use back button focusing to solve this problem because the distance between the photographer and the subject stays the same between both shots, but the composition changes. With back button focusing, the photographer activates focus for the first shot, and then is able to recompose infinite times as long as the distance between the camera and the subject remains exactly the same.
You'll note that there are other ways to solve this problem, such as focus and recompose (equally tedious, but sometimes it's your best bet), or holding the AF-L, AE-L button, but that is just plain annoying. Back button focusing is superior in this instance as long as the photographer is careful not to change the distance between the camera and the subject (which would throw off the focus) when using shallow depth-of-field.
Example number two
While I was shooting wildlife in Yellowstone earlier this year (read about that trip here), I came amazingly close to a pack of wolves one morning (well, close as in it filled the frame with a giant 800mm lens… I wasn't THAT close…) and I shot as fast and furious as possible as the famous Alpha 06 wolf played in the snow in front of me.
Just as I was shooting madly, another photographer scooted too close in front of me and my 800mm lens began to focus on the photographer's shoulder! Focus on such a long lens can be somewhat slow, and by the time I readjusted my heavy tripod and lens, the wolf was running away and all I got was butt shots.
In the same situation, back button focus could have saved me. When the photographer's shoulder appeared in the frame, my focus would have been locked on the wolf still and I could have shot to the side of the photographer and still got sharp shots as soon as I shewed him out of the frame. Instead, I had to find focus again in low light with a plain white field of snow in front of me (meaning focus was tough to acquire).
Tutorial: Back Button Focus for Canon
Canon was the first camera manufacturer to implement back button focus in 1989 and has put the feature in all DSLR models made in the last 8 or 9 years (yes, even the Canon Rebel XT and XTi).
In the Canon camera menu, you'll look for an option called “Shutter/AE Lock Button” and then in that menu you'll see a whole host of options. The one you're looking for is called “Metering Start / Meter + AF Start.” Could they have possibly made that any more confusing for us photographers? No… I think not.
The following is a cheat sheet from the Canon Learning center where you'll find the menu option on your Canon camera to set up back button focus. If your camera isn't listed here, just poke around a bit and I'm sure you'll find it easy enough.
EOS Rebel T3: C.Fn 7 (option 1 or 3)
EOS Rebel T3i: C.Fn 9 (option 1 or 3)
EOS 50D: C.Fn IV-1 (option 2 or 3)
EOS 60D: C.Fn IV-1 (option 1, 2, 3, or 4)
EOS 7D: C.Fn IV-1 (Custom Controls — Shutter, AF-ON, AEL buttons)
EOS 5D Mark II: C.Fn IV-1 (option 2 or 3)
EOS-1Ds Mark III: C.Fn IV-1 (option 2 or 3)
EOS-1D Mark IV: C.Fn IV-1 (option 2 or 3)
More advanced Canon cameras have a dedicated button on the back of the camera that will be the button used to activate the focus on the camera, and other Canon cameras (such as Canon Rebels, Canon 60D, etc) will use the AF-L, AE-L button as the button that will activate focus after this option is selected.
Tutorial: Back Button Focus for Nikon
On a Nikon camera, it is a bit easier to set up back button focusing than it is on a Canon, but you still have to know exactly what to look for.
There are dozens and dozens of Nikon model DSLR cameras, so I can't go through each of them, but if you follow one of the tutorials below for a similar camera to your model, I'm sure you'll get it set up easy enough.
Back Button Focus on a Nikon D7000
1) You need to assign the AE-L, AF-L button (yes, that button that you've never used before and always wondered what it does) on the back of the camera to be AF-On. To do this, go to your camera menu and look in the custom setting menu (the pencil). In the custom setting menu, go to Controls, and then choose F5 “Assign AE-L/AF-L button.” Within this menu, choose “AF-On.”
2) Now you need to set up the camera so it will take a picture even when focus has not been achieved. This is preferable in most situations because you may have focused and recomposed the shot. To do this, go to your Custom Setting Menu and choose Autofocus. Within this menu, select A1 “AF-C priority selection” and set it to “release.” Then set AF-S priority selection to “release” as well.
Back Button Focus on a Nikon D3100, D3200, or a D5100
Check out this video tutorial that explains step-by-step how to do it.
Should all photographers use back button focus?
Definitely not! If you're not yet 100% comfortable with operating your camera or if you don't quite understand how focus works, then head for the hills, hide yourself in the corner, and grab a teddy bear for protection. Back button focusing will only make using your camera more complicated–which is why camera manufacturers for decades have used the half-press shutter method of focusing.
If, however, you're a confident photographer and you're ready to try an advanced technique that can definitely improve your focus in some situations, then meet back button focus.
I thought back focus was a bad thing!
Back focus and back button focusing are two very different things. Back focus is when the lens focuses behind the intended target, and back button focusing is a technique used by advanced photographers to focus by separating the focus and shutter activation of the shutter button.
Before you run off, I want to share with you some of my very best Youtube videos. These are all on-location videos where you can see how I'm using the color in sunsets, choosing my compositions, etc. Enjoy, and don't forget to hit subscribe so you can see my future Youtube vids!
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