For most photographers, focusing the camera is intrinsically linked with half-pressing the shutter button. But there is another way to focus, which many photographers swear by. It’s called back button focusing. In this guide, we’re going to look at how it works and what it can do for your photography.
What many people don’t realise, particularly if they’ve only ever used digital cameras, is that the inclusion of autofocus on cameras is a relatively modern concept only introduced in the mid-1980s. The most common way of focusing a camera (and what we know as manual focus today) was by adjusting the focusing ring on the lens of a camera. Minolta were the first manufacturer to introduce autofocus that was built into the shutter button and the concept took off.
On modern DSLRs you’ll find a huge number of autofocus points – up to 63 on some models. There are a huge variety of ways to use them as well, ranging from selecting a single point, selecting groups of points or simply letting the camera choose the point it thinks is most suitable. With all these options, having another way of focusing may seem somewhat obsolete. But back button focusing can actually make focusing even easier and indeed more creative.
Back button focusing was invented by Canon in 1989 and first appeared on their EOS630 model. What it essentially allowed users to do was go into the menu and instruct the camera to use a separate button on the back of the camera to handle focusing. Although it wasn’t a great success, the feature has been included by all the major camera manufacturers ever since.
Many advanced cameras have an “AF-ON” button on the back, and if your camera has this, this is the button that will be used for back button focus. If your camera does not have this button, then you can program one of the other buttons on the back of your camera to handle back button focussing (often the AF-L or AE-L button).
To use back button focus, the focus function needs to be removed from the half-press of the shutter button and reassigned to a separate button on the back on your camera. This is done through the menu on your camera, and as each camera has a slightly different way of setting this up, the best option is to simply Google your “camera make and model + back button focus” for instructions on how to set this up on your particular camera.
Once back button focus is activated, you use your thumb to press the button on the back of the camera to focus, and your index finger as usual to press the shutter. It’s not something that you’ll get used to immediately, but it is worth learning about, as it opens up amazing new possibilities.
Reasons To Use Back Button Focus
Probably the primary reason to use back button focus is to remove the need for refocusing if you take your finger off the shutter. Because it’s so natural for photographers to keep our finger half pressed down on the shutter button to focus, we never really stop to think about what an awkward manoeuvre it is! It’s very easy to accidentally take your finger off the shutter and then have to refocus.
The huge advantage of back button focus is that it allows you to set the focus once, and that focus will then stay set until you change it again manually. This can be particularly useful in situations where you need to make sure you’re focusing on the same subject time after time.
Back button focus is also very useful for cameras that only have the two main types of autofocus modes – Single and Continuous. These are labelled on Canon cameras as One Shot and AI-Servo, and on Nikons as AF-S and AF-C. As the names suggest, single mode focuses on a still subject that isn’t moving, whereas continuous mode allows photographers to track their subject as they move, with the camera continually refocusing.
Using the continuous mode with back button focusing takes a little practice, but the results are definitely worth it, as you’re much more likely to be guaranteed sharp shots. When you’re using continuous mode with back button focusing, you’ll need to continuously hold down the AF-ON button in order to track focus.
As long as you keep your finger pressed down, the camera will continue to look for a moving subject, by going slightly in and out of focus. Once your subject is in focus, you can simply let go off the AF-ON button, keep your focus and then fire your shot.
Back button focus makes it faster, in general, just to focus. It’s far faster than changing to a specific autofocus point, as you can just focus your shot using the centre AF-point and then release your thumb from the back button once you’ve recomposed and framed your subject.
Probably the best way to illustrate how back button focus can improve your photography is by way of an example, so watch the video below to see exactly how this works in practice.
Using this function isn’t something that will come naturally to any photographer straight away, as the way it works is a little counterintuitive to most of us.
But it worth persevering with, as the results you can get from it make it worth its while. And remember, it also frees up your shutter button to be used for another function if required. But that’s a whole different article…!