Essential Guide to Back Button Focus

What is Back Button Focus?

A handy feature on your camera you may not be familiar with is back button focus, often referred to as back button autofocus.  When using this feature, a button on the back of your camera (hence the name, back button!) is used to lock in the focus of your shot, rather than having to continuously press the shutter button halfway, then shoot.  Basically, the feature removes Autofocus from the shutter button and transfers it to a button on the back of your camera.

All of the current DSLRs being manufactured by Nikon and Canon's EOS line have this feature.  In this tutorial, we will be looking at how to activate back button AF on the Nikon D610 and 5D Mark II, however, activating back button AF is similar on all Nikon and Canon EOS cameras, just consult your user manual.

Now, you may be asking yourself "whats the big deal with back button focus and why should I go through these extra steps to activate this feature.

Why Use Back Button Focus?

• Faster shooting with static subjects: you can lock focus with the AF button once then let go of the button for subjects that don’t move.  This is great for landscapes, macro, even sleepy newborns.  No need to refocus every time you press the shutter.

• Easier to focus and recompose: you can lock focus using your center focal point with the AF button then let go of the button and recompose your image very easily without having to re-do your focus each and every time you press the shutter.  Useful for Canon cameras with limited focal points or if your initial composition is not optimal.

• Better focus for moving subjects: you can shoot continuously with the AF button depressed and your focus will track your moving subject.

• Override and fine-tune autofocus: you can ensure tack sharp images when using Live View and zooming your focal point in to 100%, then locking in that focus by using the AF button.  You can even adjust your focus manually by turning your focus ring on the lens without turning the switch to manual on the front of the camera (if required).

There are several scenarios that are perfect for using Back Button Focus.  Lets take a look at these below:

Back Button Focus Example 1: Weddings

Let’s say you are photographing a wedding, and, during the ceremony, the bride and groom are going to be in the same spot for an extended period of time.  By selecting the focus only once, and having the ability to continuously press the shutter without the camera refocusing for every shot, you will be able to more easily capture facial expressions and gestures that happen within a fraction of a second.  If you are continuously refocusing during the wedding ceremony, you might miss some really great moments!

Back Button Focus Example 2: Portraits

Portraits are one area that I wasn't sure I would find much use for back button focusing.  I was completely wrong.  Using back button focusing along with the continuous focus feature allows me to track moving subjects much more efficiently.  Portrait subjects are never perfectly still (especially children) so I use this same combination anytime I have children as my subjects or if I ask my subjects to walk or move.

Back Button Focus Example 3: Moving Subjects

While back button focus may seem like it is best-suited for relatively stationary subjects, it can be very useful for moving subjects, as well.  For example, if you are shooting a sporting event and you have a particular subject you want to be in focus, you can lock in the focus on where your subject will be, without worrying about the camera autofocusing on someone else (other players, referees, spectators, etc.)

How to Activate Back Button AF on a Nikon D610

Here are the steps to activate this feature on your Nikon D610.  This will give the AE-L/AF-L button the ability to focus and take that ability away from the shutter button.

1. Press the Menu button the back upper left of the camera.
2. Using the Selection Dial on the back right of the camera arrow to the left and select the Pencil or "Custom Setting Menu".
3. Using the Selection Dial, arrow to the right and scroll down to f/Controls. Arrow to the right.
4. Scroll down to f4/Assign AE-L/AF-L Button.  Arrow to the right.
5. Scroll down to AF-ON.  Press the OK button in the middle of the Selection Dial.

How to Activate Back Button AF on a Canon 5D Mark II

To activate this feature on your Canon 5D Mark II, just follow these steps.  In order to activate this feature, you must be either in M, Av, Tv or P modes.  Back button AF will not work in full auto mode.

1. Press the Menu button on the top left back of your camera
2. Scroll over to the second tab from the right (it is an orange camera icon with metering lines underneath)
3. Scroll down and select C.Fn IV: Operation/Others
4. Select either option 2: Metering start/Meter+AF start or option 3: AE lock/Metering + AF start (see below)

Here are the differences between options 2 and 3:

Option 2: Metering Start/Meter+AF Start

Option 2 activates the back button AF, removing AF control from the shutter button.  The shutter button will still fire the shutter, though.  With this option, the camera metering is updated every time you take a shot, so if you are shooting in Shutter or Aperture priority, the camera will still automatically adjust these values to compensate for any changes in lighting.

Option 3: AE lock/Metering + AF start

Just like option 2, this setting shifts the AF from the shutter button to the back button, however, it also locks the metering.  So, the shutter and aperture values that you have when you lock the focus will be applied to all subsequent shots.  This feature is useful if you are shooting in lighting conditions that will not change, such as a studio.

Back Button Focus Technique

Just like any new technique you learn, back button AF takes a little bit of practice, but once you get used to it, I'm sure you will find it’s a very powerful and useful feature.  I was hesitant to use it initially, but once I tried it I never went back.

If you set your camera to continuously focus, you can hold down the back button and the camera will continuously focus.  I love this feature for moving subjects but also use it often with portraits because most subjects don't hold perfectly still.

Some new photographers may feel like this is just an extra bother.  However, one thing that I noticed after trying Back Button Focus was that more of my images were in focus.  Using this feature allowed me to cut down on the number of accidental captures and realy helped me nail my focus.

Give back button focus a try before your next shoot, and you may find that it is one of those cannot-live-without features on your camera!

Do you have any questions or comments about Back Button Focus?  Leave us a comment below - we would love to hear from you!  And PLEASE SHARE our tutorial using the social sharing buttons (we really appreciate it)!