What is Back Button Focus all about?

Started 8 months ago | Discussions thread
enemjii
Senior MemberPosts: 1,443Gear list
Like?
Re: What is Back Button Focus all about?
In reply to Dareshooter, 7 months ago

enemjii wrote:

Phhoenyxx wrote:

Phhoenyxx wrote:

enemjii wrote:

I read through the postings and I figured it is a Focus lock button. Did I get that right?

No, it's an autofocus triggering button. If you want it to lock focus you set the camera to AI Servo and lift off when you want to lock focus, and back on again when you want autofocus to go again. Try it!

Does it need to be on AI Servo?

No it doesn't need to be, but if it's in One-shot that will lock the focus on the subject for you, rather than you lifting off the button. So you see how it's not a subject-in-focus lock-by-lifting-off button unless you're in Servo?

I thought that as soon as you let go, it is essentially locked because it doesn't refocus, so you can take as many shots as you like without pressing it again.

In One-shot it will do that if you don'tlet go. Try it!

In One-Shot, you keep pressing until it achieves focus. Once it achieves focus and you let go of the button, what happens? Does it somehow lose that focus?

Only if you press it again. (But you knew that because you tried it, right?) That's why it's an autofocus triggering button, not an autofocus locking button. You don't generally define the function of something by what it doesn't do when you don't use it.

-- hide signature --

Check out the unofficial Rebel Talk FAQ.

Whaaaa... That is just semantics. It is a focus lock button. A rose is still a rose....

-- hide signature --

Let me refine it... It is a focal length lock button.
Happy?

The only way to lock the focal length  is to let go of the zoom.........or use a prime. Wilba and others are not using semantics,they're telling it as it is.

Here it is - All said and done, the button activates focusing, instead of the shutter button. If you do not press the back button, it will continue to shoot at the focus distance that was shot last, in effect, providing you with a focus distance lock.

read below....

You can use back button focusing to solve this problem because the distance between the photographer and the subject stays the same between both shots, but the composition changes. With back button focusing, the photographer activates focus for the first shot, and then is able to recompose infinite times as long as the distance between the camera and the subject remains exactly the same.
....
my focus would have been locked on the wolf still and I could have shot to the side of the photographer and still got sharp shots as soon as I shewed him out of the frame.

https://improvephotography.com/4552/back-button-focusing/

-- hide signature --
 enemjii's gear list:enemjii's gear list
Sony SLT-A65 Sony DT 35mm F1.8 SAM Sony DT 16-50mm F2.8 SSM Sony DT 18-135mm F3.5-5.6 SAM +1 more
Reply   Reply with quote   Complain
Post (hide subjects)Posted by
Keyboard shortcuts:
FForum PPrevious NNext WNext unread UUpvote SSubscribe RReply QQuote BBookmark post MMy threads
Color scheme? Blue / Yellow