UKH

I had a dabble years ago with my old dSLR cameras but never really tried with my mirrorless cameras. Is this a technique consigned to history, now that cameras are so fast at focusing, or is it still a good skill to master?

Use it all the time for bird photography now. Started around Aug last year after a bird photographer who has a far quicker and more accurate dual focus with AI Nikon dslr explained how it helped him.

My Olly MFT is not great for the speed of auto focus anyway with small subjects like birds (or in lower light, lack of contrast with background, etc), in relative terms of the speed of other modern cameras, for action shots but using back button focus has helped massively to reduce the time to focus on the subject more accurately. It has overall increased my hit rate for getting reasonable shots significantly, and indeed getting some shots that were almost impossible beforehand.

Definitely useful for my level of amateur photography for bird shots where I use continuous focusing. Don’t use it for landscape shots or other single focus shots where I have time to compose the shot.

I use it for cave photography all the time. Before I figured it out, I flicked the AF/MF switch on the lens after focusing. 

I light the object, back button focus on it, then it's fixed and I can keep the camera the same distance from the object and concentrate on getting the flash lighting correct. It stops the camera focussing on something else by accident. 

Gallery here :

https://www.flickr.com/photos/195853234@N06/

Specific example where I wish I'd spent a bit of time focussing properly on the face :

https://www.flickr.com/photos/195853234@N06/52137821211/in/datetaken-public...

I use it on my Nikon D500. The main advantage for me (wildlife photography) is that I can leave the camera permanently set on continuous AF without any need to ever switch focus modes. For tracking a moving subject I can just keep my thumb on the back button all the time, for static subjects I can take my thumb off the back button after focusing which then locks in the focus so the camera won't try to refocus when I half press the shutter release.

When I first tried it I thought my thumb and forefinger would get hopelessly muddled as to what they were supposed to be doing but I actually found it very intuitive. I wouldn't want to go back to having the focus on the shutter release now. I now use it for landscapes as well when I'm out on the hills so I can quickly focus on the point I want to and can then recompose knowing that the focus won't change.

Steve Perry has a good video on it somewhere on his website although it's primarily aimed at Nikon users. The principles still apply to other makes though.

Surely back button focus is the only way? I can think of only advantages over half pressing the shutter e.g. Decouples exposure from focus, allows you to combine af tracking and single shot focus in a single 'mode',  allows for quick recomposition once focus is achieved once...

Now that's a pretty impressive gallery!

Can't think of a scenario in which it wouldn't be better. Gives you total control and pretty easy to commit to muscle memory.

I use it all the time. Its not a matter of speed of focussing its being able to choose where you want the focus point in the image.

Dave

Its the only way, I would never go back , only trouble is whenever I pass the camera to someone to take a photo with me in it’s invariably out of focus 

I've found, at least on a Canon 600D, that even if you enable back-button focus that only applies in any of the 'creative modes' or in full manual M. If I move the dial back into full auto mode then half shutter focussing is enabled. I can just move it to this mode before passing it off to anyone else to use. 

Hah, that sounds very familiar! Back button focusing all the way, been using it for years and I really can't imagine going back. Why would you?!

My Fuji is set up the same, in Manual or continuous Focus mode Backbutton focus is enagaged, If switched to fully auto focus it reverts to using the shutter button.

So is the 'back focus" button just another name for the focus lock button, or am I missing something?

Not sure.

My Panasonic GH4 was shocking for focusing high moving subjects and I experimented with Back Button focus. I still had a very poor hit rate for sharp images.

My GH5, GH6 and G9 have 95% hit rate for sharp images just using the shutter button. If I want steady focusing I just put the camera into manual focus.

Focus lock is the opposite of back focus, you have to use the shutter button to focus, then press the focus lock to hold that focus point, not very fast or intuitive.

Ok. It seems that my AF-L button can be programmed to do various things including back button focus which is what I have been thinking of as focus lock.

So I just flick a switch to turn off and on continuous focus rather than keeping focus with my thumb?

I use my Olympus E-M5 for bird photography and landscapes. I've saved my bird settings into the custom mode on the camera, with the AFL/AEL button for focusing. That way I don't have to keep changing settings. There are several YouTube videos showing how to do this.