Back button focus

What is the advantage of using back button focus (BBF)?
folk talk as though its better than having the camera set to use1/2 press of the shutter as i often read the advice given if folk are having AF problems to try BBF ,,but is it not only a different way to activate AF..
I try it many years ago on a 20D and found no advantage and for me was less intuitive
so why use BBF?

I think the main benefit is to keep the focus and shutter release process separate but I have tried it on several different cameras and like you, found it very awkward to use and it upsets the handling in my view

Yes, in some cases, exposure metering, focus and shutter release are wanted to be handled separately. There is a lot of middle ground to it with different metering and focus modes. Just find what best suits you.

AF-ON for focusing, when you understand its usefulness it is difficult to go back 🤓
This configuration allows us to use AF-C and AF-S instantly, It's awesome! 👍🏻

You keep your finger pressed on AF-ON = AF-C
You press and release AF-ON = AF-S
And the Shutter button is only for taking the picture 😃

First of all, don't get too hung up about it. It's just another of the many options you have to configure your camera to suit the way you prefer to do your photography.

There is no right or wrong answer.

Personally, after experimenting with BBF and becoming accustomed to it relatively quickly I would never go back to focussing with the shutter button. But that is just me and many prefer the shutter button for focussing and that's totally fine.

I like BBF mainly because once I set focus and release the BBF button, the focus distance remains constant until I set focus again. This is handy for when I am photographing different subjects at the same distance from the camera; I set focus once and forget it.

I also find it handy when aiming the camera to focus on the off centre subject and then need to recompose to take the shot. With BBF I don't need to hold the shutter button half way down to retain focus while recomposing.

I also find BBF handy when I am composing and waiting for something to happen. I set focus using BBF button and release it. I don't have to continually hold the shutter button half way down while waiting for the action.

So, maybe try both options and just see which is the most comfortable and works best for you.

Thank-you for your detailed response. After 40 years of photography I have started using AF more often in the past two years. I have been skeptical of the BBF method but now I understand it's possible use.

that do sound if it could be useful

This is why I use it.

The only annoying thing with my Canon, when reviewing pictures in the camera it doesn't show the focus spot when using "You press and release AF-ON = AF-S" method. It'll only show it when the AF-ON is held.

It really depends on the camera you’re using and how it’s configured. I use BBF in Manual mode all the time with my Fujis (which doesn’t require disabling AF on the shutter button), but I get WAY better results (and flexibility) using the shutter button for regular AF duty.

This is why I use it.

The only annoying thing with my Canon, when reviewing pictures in the camera it doesn't show the focus spot when using "You press and release AF-ON = AF-S" method. It'll only show it when the AF-ON is held.
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Of course. When you let back button go camera is not focusing and no focus point used.

Where back button focus really shines for me is when I'm shooting video. I can hit the button to get the camera to focus where I want it and then shoot without having to worry about the focus shifting during the shot.

I quickly got used to using BBF and I'd never go back to using the shutter button to focus. Here's a video that explains why BBF is more efficient, and how to set it up for Nikon cameras.

The newest models allow you to use one focus method with one back button and another with the asterisk or some other button. I can use single point or full screen tracking just by picking the left or right button. That’s pretty fantastic too.

I don't even know anymore, why they invented that half-way press. BBF is so much easier once you get used to it.

In the DSLR era, camera autofocus systems typically had their autofocus points clustered near the center of the field of view. As a result, if you wanted to compose a shot with the subject placed off-center, there was a good chance no autofocus points would cover the subject. Back button focus (BBF) moved autofocus activation away from the shutter release to a button on the back panel of the camera. A photographer could set focus on the subject, recompose to position the subject off-center and press the shutter release to make a photo without the camera refocusing on something near the center of the frame. This technique became known as focus and recompose.

Mirrorless cameras typically have many more autofocus points and they normally cover nearly the entire field of view. Focus and recompose is only rarely - if ever - needed when doing photography with a mirrorless camera. However, BBF does offer advantages to mirrorless (and DSLR) shooters that go beyond facilitating the option of focusing and recomposing.

The core principle of BBF is the act of moving focus activation away from the shutter release button. Dissociating focus activation from the shutter release allows for two or more autofocus modes to be readily available to the photographer. I'm a wildlife and bird photographer and my primary body is the Nikon D500. I've configured the camera to activate my primary autofocus mode with a press of the AF-ON button. I also have a direct press of the camera's thumb stick and a press of the preview (Pv) button configured to activate second and third autofocus options.

To illustrate, when photographing a bird in flight, I'll use my right thumb to press the AF-ON button to activate continuous autofocus (D25 - a central cluster of 25 AF points) to acquire and track focus on a bird against a clear blue sky. If the bird dives and starts flying low enough to be positioned against a background of dense vegetation, I'll press the Pv button with my right middle finger to activate Group autofocus. Group gives priority to the nearest moving object and does a better job of ignoring the background than D25. If the bird lands and settles into being perched for awhile, I'll directly press the thumb stick to activate single-point autofocus. I'll positions that one AF point to cover the bird's head. All the while, my right index finger is free to hover above or press the shutter release button to trigger a burst.

Pressing AF ON to activate continuous autofocus, D25

A direct press of the thumb stick to activate single-point autofcus

Pressing the Pv button to activate Group autofocus

While not strictly a BBF technique (the Pv button is on the front panel of the camera) this strategy deploys the central principle of BBF...moving autofocus activation off the shutter release button. Another advantage of BBF emerges when acquiring focus on a fixed element of a landscape or cityscape composition. Once I have locked down a composition on the tripod and acquired autofocus where in the composition I want, the only thing I want the shutter release button to do is to initiate a shutter actuation. As good as my camera's autofocus system is, is not perfect. If the camera reacquired focus every time I pressed the shutter release, it would make at least a few photos in which focus was missed. By using BBF, I can acquire sharp focus wherever I want in the frame and keep it locked in as I make exposures in the evolving light.

As autofocus technology continues to advance and become more customizable, I envision more photographers will discover the benefits of having multiple customized and customizable autofocus modes within easy reach. There may even come a day when AI technology is so reliable at analyzing the composition, recognizing what is being photographed, and choosing the custom AF mode that will deliver the best results, that there may not even be a need for the photographer to activate focus.

Until then, techniques such as BBF will continue to offer advantages that may - or may not - be of value to you as a photographer. If you're interested, give it a try. Test drive it for a few outings. If you like the experience and the results, keep using it. If not, use the autofocus activation technique that works best for you.

I’m a Canon shooter; I don’t know other systems. On Canon, continuous autofocus (Servo Mode) is predictive. It is not as precise as “One Shot,” so if you want precise focus on an object, it’s still best to use One Shot. In Servo Mode, if you hold the button down on a static object, the camera will continually "hunt" to try to improve focus.

With the R series Canons, especially R5 and R6, BBF has a new benefit: It can be used to configure the focus mode. The new Eye AF is great… except when your subject doesn’t have eyes. So in this case, we can configure two (or even three!) BBF buttons, one with Eye AF and another with Object Detection.