What is back button focus
The normal set-up of most cameras is that the button to activate the focus system is the shutter button; so to take a photo, you press the shutter button half way down until focus is achieved (usually indicated by a box on the LCD going green) then you press the shutter button fully down to take the picture. There are some situations where this is still the best method to use, however a lot of professionals (including myself) prefer to use another method called 'back button focus' in many situations.  Back button focus is a technique where the focusing function is separated from the shutter button and assigned to a button on the back of the camera. This means that the button on the back of the camera is used to achieve focus, and then separately the shutter button is pressed to take the photo.Â
Advantages of back button focus
There are a number of important advantages to using back button focus. These include:
Increased focus control
By assigning focus to a separate button, you can focus independently of taking a shot, allowing you to lock focus and recompose your shot without the camera refocusing every time you press the shutter button.
For moving subjects, you can hold down the back button to maintain continuous focus (AF-C) without affecting your ability to quickly take multiple shots.
Faster response time
When switching between subjects at different distances, back button focus lets you quickly refocus without the delay of half-pressing the shutter button.
You can lock focus instantly by releasing the back button, enabling faster reaction to changing scenes or movements.
Improved compositional flexibility:
After focusing on a subject, you can recompose your shot without worrying about the camera refocusing on a different part of the scene when you press the shutter.
For static subjects, once you’ve locked focus, you can take multiple shots without needing to refocus each time.
Using back button focus allows you to gain greater control over your focusing, leading to more precise and reliable shots, which is why it's a favoured method among many professionals and enthusiasts.
When to use back button focus
There are a number of situations when back button focus is the preferred method of focussing. These include:
Action and Sports Photography:
When tracking fast-moving subjects, BBF allows you to maintain focus continuously by holding down the back button and then capture the shot at the perfect moment by pressing the shutter button.
Wildlife Photography:
Similar to sports photography, BBF is useful for tracking animals in motion. It allows you to keep focus on the subject and shoot when the composition is right without the camera trying to refocus.
Portrait Photography:
When photographing people, you can focus on the subject's eyes, lock the focus by releasing the back button, and then recompose your shot without worrying about the focus shifting.
Landscape Photography:
For static subjects like landscapes, BBF helps in focusing on a specific point in the scene, locking the focus, and then composing the shot without the risk of the camera refocusing on a different part of the scene when you press the shutter button.
Macro Photography:
Macro photography often requires precise focus. BBF allows you to lock focus exactly where you need it and avoid focus shift due to the shallow depth of field in close-up shots.
Low Light Photography:
In low light conditions, autofocus can struggle. BBF lets you lock focus once achieved and then take multiple shots without refocusing, reducing the chance of focus errors.
Disadvantages
Although back button focus has many advantages, it does also have some disadvantages:
Learning curve: Switching to BBF requires a period of adjustment. Photographers accustomed to half-pressing the shutter button for focus might initially find BBF awkward and unintuitive.
Complexity for beginners: For new photographers, BBF can add unnecessary complexity. It requires additional coordination and understanding of camera functions, which can be overwhelming when one is still mastering basic techniques.
Potential for missed shots: In fast-paced situations, the extra step of pressing a separate button to focus might result in missed shots. This is particularly true for action or sports photography, where quick reactions are essential.
Switching between modes: If you frequently switch between manual focus and different autofocus modes, BBF might complicate the process. It can be easy to forget which mode you're in, leading to potential focus errors.
Battery Life: Using BBF can sometimes lead to increased battery drain. This is because the autofocus system might be engaged more frequently or for longer durations compared to using the shutter button for focus.
Not all cameras have it: Not all cameras support BBF, and even among those that do, the implementation and button customization options can vary. Some cameras might not have a dedicated AF-ON button or might not allow sufficient customization of other buttons.
How to set up back button focus
The exact method for setting up back button focus will vary from camera to camera, and you should either check your manual or do an internet search for help articles / videos for your specific camera. However, the basic procedure is as follows:
Locate a suitable button: Find a button on the back of your camera that you can use for focus. It's usually best to use one near to the shutter button and many cameras have a dedicated button labelled AF-ON or AE-L/AF-L.
Change camera settings: Access your camera’s menu to reassign the autofocus function from the default shutter button to the chosen back button. This usually involves disabling autofocus from the shutter button and then enabling it on the back button.
Practice: Get used to the new focusing technique. It might take some time to adjust, but practicing will help you become proficient.
Want to improve your photography skills?
Don't forget that if you want some direct help with your photography, I offer a range of 1-2-1 photography courses for Devon based folks. If you're not nearby then I also  offer residential weekends for beginners or intermediate photographers.
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