If you’ve read photography blogs, hung out on photography forums, or hung out with other photographers, you may have heard the term “back button focus” mentioned. It’s possible you’re not sure what it’s all about, or maybe you heard that you can get sharper photos with back button focus but you’re not sure how. You might even wonder if it’s something you need to do or not. This post will break all that down for you.
First, what is back button focus?
Simply put, back button focus is using a button on the back of your camera to achieve focus rather than using the shutter button for focusing. It will depend on your camera brand and model as to which button exactly you will use for this function. I shoot Canon. Pictured below is one of my Canon bodies; the AF-ON button on the top right is used for back button focusing (BBF) on both of my bodies. Other Canons use a different button, depending on the model. Different brands also have slightly different setups, so consult your camera manual to determine exactly which button is used for back button focusing.
What is different about back button focusing (BBF) and how can it give me sharper images?
Technically, using the back button to focus does the exact same thing as the shutter button: it focuses. It doesn’t use any different method that will inherently give you sharper photos. On the surface, both buttons do the same thing. There are a few advantages to back button focus — and they can help you get sharper. The main advantage of BBF is that it separates the shutter button from focusing. When you focus with the shutter button, you are both focusing and releasing the shutter with the same button. With BBF, these two functions take place with different buttons.
You can use BBF in different focus modes. If you are using one shot/single shot mode, you can press the back button once to lock focus and focus will remain in that specific spot until you press the back button again to refocus. This is advantageous if you need to take a number of photos (such as portraits or landscapes) with the same composition and focal point. You do not need to worry about the lens refocusing each time you touch the shutter button; your focus is locked until you decide to change it by pressing the back button again.
If you’re using servo/AF-C mode, back button focus can come in even more handy. When you’re using this focus mode, your lens’ focus motor is continually running, trying to maintain focus on a subject you are tracking. You may also be firing off a number of shots while you’re doing this focus tracking. Say you’re using shutter button focus and you’re tracking a subject, but something comes between your lens and your subject. With shutter button focus, your lens will attempt to focus on the obstruction as long as your finger stays on the shutter button, shooting photos. However, when you focus with the back button, this is not a problem. Remember how I said that BBF separates the shutter button from focusing? This is where it comes in really handy. With BBF, if you notice an obstruction come between your lens and your subject, you can simply remove your thumb from the back button and the lens focus motor will stop running and will not focus on the obstruction. You can still continue to shoot if you wish. Once the obstruction moves, you can put your thumb back on the back button and resume tracking focus on your moving subject.
Is back button focus necessary?
No. It comes down to being a matter of preference. There are some photographers who do benefit from it, such as sports photographers and wedding photographers, but even they don’t have to use it. I use it because I tried it, liked it, and became accustomed to using my back button to focus. It now feels natural to me. Try it to see if you like it and if it fits your shooting style. If you don’t like it, you can always go back to shutter button focus.
How do I set up back button focus on my camera?
The exact process for setup will vary depending on your camera brand and model, so it’s best to consult your manual to determine how to set up back button focus on your specific camera. A couple of tips (I’ve learned these from experience!): some camera models have the option of having both back button and shutter button focus active at the same time. Be certain that you are picking the mode that is dedicated specifically to back button focus only. Also, if you have a wireless camera remote that allows for autofocus, chances are your camera body won’t autofocus using the remove if you have BBF set up on the camera. If you do need to autofocus and use a remote, you’ll need to change the camera back to shutter button focus temporarily.
Back button focusing is not a necessity but is an option that many photographers find indispensable. Now that you know what it is and what its benefits are, try it out and see if it’s for you!