What operation on a camera could possibly be more simple than pressing the shutter button to take a picture? There’s not much to it, really – you look through the viewfinder (or at the LCD screen on the back of the camera), press a button with your index finger, wait for the camera to focus, and voilà! You’ve got a photo.
Well, as the popular saying goes, what if I told you there was a better way? Hidden deep within the settings of most cameras is a feature called Back Button Focusing, and enabling it can transform your approach to photography.
A Brief History
To understand what Back Button Focusing is, it’s important to know a little about the history of the autofocus function on your camera. Until the mid-1980s, there was no such thing as autofocus on consumer-level film cameras. You had to hold your camera up to your eye and either turn a ring on the outside of the lens or adjust what’s known as a rangefinder in the top-left corner. It required a great deal of patience and practice, and there are many photographers today that still swear by this method.
In 1985 Minolta released the Maxxum 7000 which integrated the autofocus function into the shutter button, which seemed like a sensible choice because you would normally want to make sure the camera was focused before taking a photo. This implementation of autofocus worked well, but required a bit of maneuvering if the photographer wanted to focus on something other than what was in the center of the photo. To do that, he or she would have to aim the camera at the object to be in focus, carefully hold the shutter button down halfway to keep the focus locked while re-composing the shot, then pushing the button all the way when the picture was ready.
This system remains in place on most cameras today, and it’s probably how your own camera operates. At this point you might be wondering why you should bother to change something that has worked perfectly well for the past 30 years.
The answer is because there really is a better way to focus your camera before you take a picture, and it was invented by Canon in 1989. On their EOS 630 camera they included an option within the camera’s custom settings menu to separate the actions of focusing and snapping the shutter. Users could tell the camera to use a separate button on the back of the camera to handle focusing duties, which left the shutter button to do one thing and one thing alone: take the picture. It was not an immediately obvious feature, and it never really caught on like Canon may have hoped, but the same capability is in every Canon DSLR today as well as virtually all cameras from other manufacturers like Nikon, Pentax, Sony, and the rest. If you have any sort of DSLR or mirrorless camera there is probably an option in your settings menu to enable Back Button Focus, and it’s something I highly recommend trying out.
Back Button Focus requires your thumb to press a button on the back of your camera (hence the name) and your index finger to press the shutter, which does take a few days to get used to, but soon becomes second nature. All this begs the question – why should you re-learn how to do something as basic as focusing your camera when the shutter half-press works perfectly fine? The answer lies in the overall concept of giving more control back to you, the photographer.
More Creative Freedom
Cameras today have a dizzying array of autofocus points – those little dots or squares that light up in the viewfinder when you press the shutter button down halfway. You also have a ton of options in how you use these points. You can select an individual point, you can have the camera select what it thinks is the best one, you can tell your camera to use some of them in conjunction with one another, and many cameras have modes such as automatic face detection as well. To be honest, all these options works really well. But just know that by decoupling the act of focusing from the shutter button, and moving it to a separate button, you will be able to do a lot more with your photography than you may realize.
By using a button on the back to focus, you will no longer have to hunt around for the specific autofocus point you want to use or wait for the camera to focus on what it thinks you want to before allowing you to take a picture. Trying to keep a moving subject in focus while deftly holding the shutter down halfway is a feat of dexterity that would keep Legolas himself at bay. This is easily remedied by using back button focus. With this method you can hold the back button down as long as you want, which keeps your camera continually focusing on your subject, until you are good and ready to snap a photo. This is incredibly useful when your subject is in motion, whether people, animals, mechanical objects, or simply a flower petal meandering across a meadow.
One of my favorite cameras is the Nikon D7100, which has 51 autofocus points that cover almost the entire frame. For a while I used all of them, frantically shifting from one to the next as I adjusted each shot or tried to track a moving subject. It worked fairly well, especially in conjunction with Nikon’s 3D subject tracking algorithm (variants of that can be found in most cameras today) which did a good job of keeping my subject in focus whether it moved or I altered my perspective. But I found that I often messed up some critical shots because I was either too busy changing the autofocus point, or letting my camera decide what it thought should be in focus. Switching to back button focus remedied all of this, and helped me gets shots that would have been much more difficult otherwise.