jim quist Loc: Missouri

Professional wild life photographer explains how to use Back Button Focus.

https://www.youtube.com/watch?v=sdfnvCWqb_A

DebAnn Loc: Toronto

Glad to see he was wearing a Nova Scotia T-shirt! I thought it was interesting how he described using BBF to hold the focus while moving the camera around. I do the same thing by holding the shutter button down halfway. So if I'm wanting to put a bird, for instance, off centre, I just use single focus point (middle) to focus on the bird and then simply move the camera till it's off centre and press the shutter button down. Seems to achieve the same thing without changing the camera to back button focus.

nervous2 Loc: Provo, Utah

Nice tutorial.

amfoto1 Loc: San Jose, Calif. USA

No, you are not doing the same thing.

You are only getting away with focusing and recomposing by using "single shot" focus mode.... the mode for stationary subjects. If you're subject starts moving, you'll need to pause to change modes and will probably not get any shots of the now-active subject.

You cannot focus and recompose that way with continuous focus mode that's used for moving subjects, because the moment you do the camera will refocus to wherever you've now put the AF point (off the subject).

The purpose of Back Button Focusing is to allow you to keep your camera in continuous focus mode all the time... to use it with both moving and stationary subjects... and to still be able to use the focus and recompose technique at will. BBF puts you in full control of starting and stopping autofocus, independent of the shutter release. The technique to do focus and recompose with a stationary subject and BBF is to press the button, achieve focus, then lift off the button and recompose, taking the shot whenever ready.

But if the subject suddenly becomes active, as they often do, you're ready for that too with BBF. Because your camera us set to a continuous focus mode all you need to do is press the back button while keeping the AF point on the subject. Keep pressing that button for as long as you want the AF to continue tracking the subject.

I also find you can use BBF to "dodge" objects a moving subject momentarily passes behind. Lift off the back button briefly, then restart AF after the subject emerges from behind the object.

Think for example of a bird on a branch that you're photographing. It's stationary for now, so there's little concern. But then it suddenly takes off and you want to get some shots of it on the wing. The AF needs to be able to correct focus as the distance between you and the subject changes. If that requires a continuous form of focus... Canon calls it "AI Servo"... Nikon calls it "AF-C".... Not sure about others, but they all have something similar.

Another benefit of using BBF and continuous focus is with many of today's zooms... a lot of which are varifocal designs. This means they don't maintain focus when the focal length is changed (i.e., when "zoomed"). If the camera is in single shot focus mode you have to consciously lift off then repress the button (either shutter release or back button) to cause the camera and lens to refocus. But if... thanks to using BBF... you are using continuous focus mode, then the camera and lens will instantly correct focus when the lens is zoomed.

BBF is the way to go if you want to leave your camera in continuous focus mode all the time... ready to use with both stationary and moving subjects!

I tried various methods of focusing with Canon SLRs and DSLRs. Learned to do BBF 20+ years ago while still shooting film and have used it on every camera ever since. It was quick to learn, soon became second nature, and vastly improved my "keeper" rate shooting sports and wildlife. Some days I take 1500, 3000 or more shots. Usually I only have to cull out one or two dozen for missed focus (and most of those are my fault, not the camera or lens').

The only cameras where BBF might no longer be very necessary are the newest mirrorless that have quite good subject, face and even eye detecting focus. Canon R3, R5, R6/R6II, R7, R8 and R10 all certainly are capable of this. But a lot of users of those mirrorless still choose to use some form of BBF... often with multiple buttons set up. Such as one with eye detection and another with small zone focus for more distant subjects. This allows them to rapidly switch between their focus setup with just the touch of a button.

P.S. Hah! I just watched the video at the above link... after writing this response. Looks like he covered pretty much all the same things, except he didn't mention varifocal zooms.

jim quist Loc: Missouri

I tried what you do with different results. I held the shutter button half way and focused on an object. When I moved to another object while holding the shutter button half way the focus changed to the new object.

mvetrano2 Loc: Commack, NY

Excellent!

Bultaco Loc: Aiken, SC

Jimmy T Loc: Virginia

[quote=amfoto1]

. . . ."The only cameras where BBF might no longer be very necessary are the newest mirrorless that have quite good subject, face and even eye detecting focus. Canon R3, R5, R6/R6II, R7, R8 and R10 all certainly are capable of this. But a lot of users of those mirrorless still choose to use some form of BBF... often with multiple buttons set up. Such as one with eye detection and another with small zone focus for more distant subjects. This allows them to rapidly switch between their focus setup with just the touch of a button. . . . "


We are in agreement, however, I would like to add the following to a small portion of your post above:
Not only does my Canon R5 focus/track on the Human Head/Face/Eye it will also track a rapidly moving "Subject to detect - People, Animals, Vehicles". There is also a - "Subject to detect" - "None"

Besides the normal focus settings, my Canon RP also has "Eye Detection AF" and "Continuous AF" that will focus/track a human Head/Face/Eye.
As such, I can't see Any Reason for me to use BBF on either of these two cameras. All I have to do is to keep the still or moving subject in the frame.
Best Wishes,
JimmyT Sends

MtManMD Loc: Beaverton, Oregon

Thanks for posting. I had not run across Simon's YouTube videos before. He's clear and concise. I'll certainly watch more of his instructional videos.

Monte

PAR4DCR Loc: A Sunny Place

Went to BBF a couple of years ago, no going back. Thanks for posting Jim.

Don

Chopper Bill Loc: East Tennessee

Combining the functions of focus and shutter on one button is a concession to point and shoot folks. Notice I didn't say point and shoot photographers. That would be an oxymoron.

Al Vocinq Loc: The wilds of upstate New York

Ditto