Back button focus

[mamatomaya]

Hi all,
I'm still working on figuring out the best way to make sure I get sharp photos and don't miss focus. Someone suggested back button focus. I want to try it out and I figured out how to change the custom function to switch it, but I thought it would make it so that pushing that one button would change the focus point, but didn't. I find it difficult to change the focus point while looking through the view finder. Any help or resources on this? TIA!

 

[Big Mike]

Rather than change the focus point, try using just the centre point.

Aim the camera at your subject (say a person). Use the back button to activate the focus and focus on their eyes. Then release the focus button (essentially locking the focus) and recompose the shot to how you want it....then fire away.

 

[Derrel]

Yes, there are some resources on this subject. SInce you are referring to "back button focus", I assume you are a Canon shooter. The Canonb, USA web site has a nice article on back button focusing at Canon Digital Learning Center - Back-Button Auto Focus Explained

The article is entitled, "Back-Button Autofocus Explained". Please keep in mind that the newer Canon bodies possess an AF-ON button, which I "think" was introduced on the EOS 30D, but maybe it was the 40D--I cannot recall which body. On other,and arlier Canons ion the 10D-20D series, there is NOT an AF-ON button, and the "*" button is used instead, so there are some major differences in how back button focusing is achieved/done, depending on the Canon camera one owns.

 

[redtippmann]

I personally LOVE to use BBF! At first I wondered why anyone would want to use it, and it felt so odd. But after shooting 2 baseball games with it I really like the way I can work with the camera now.

 

[icassell]

Switching to BBF has increased significantly my keepers. I couldn't imagine using the 'half press' method anymore.

 

[peanut170]

What is this back button that you speak of? I have a nikon is it called something else?

 

[redtippmann]

Its the AF-ON button

If you go to your CSM menu-> and go to AF activation -> AF-On only

So now it will only focus when you press that button.

 

[kami]

Its the AF-ON button

If you go to your CSM menu-> and go to AF activation -> AF-On only

So now it will only focus when you press that button.

Interesting. What benefits have you found useful as compared to the half-press method? Right off the bat, I can see having more tactile control of the camera so you don't accidentally fully press the shutter in certain situations. But I don't have experience with this.

 

[icassell]

You get your focus right ... then you can move the camera to put the object in-focus elsewhere in the field and, as you say, you don't accidentally push the shutter release.

 

[Overread]

Remember though that moving the camera away from the focused point to recompose the shot with this method can result in you missing the focus. That is because the depth of field is effectivily like a flat sheet parallel to your lens front and focused over the point of focus - however if you change the angle that you are shooting at you risk moving that "bit of paper" to a position where its no longer covering the subject you focused on.
For that reason I tend to prefer to use with method with USM/HSM focusing lenses - so that I have all the time manual focus on the lens to make any minor focus corrections if needed.

 

[icassell]

Good point! This is especially important when shooting at maximum aperture.

 

[mamatomaya]

Rather than change the focus point, try using just the centre point.

Aim the camera at your subject (say a person). Use the back button to activate the focus and focus on their eyes. Then release the focus button (essentially locking the focus) and recompose the shot to how you want it....then fire away.

Ah, I figured it out. Wow! Can't believe everyone doesn't use this all the time. So much easier!

 

[mamatomaya]

I personally LOVE to use BBF! At first I wondered why anyone would want to use it, and it felt so odd. But after shooting 2 baseball games with it I really like the way I can work with the camera now.

Totally agree!

 

[icassell]

Rather than change the focus point, try using just the centre point.

Aim the camera at your subject (say a person). Use the back button to activate the focus and focus on their eyes. Then release the focus button (essentially locking the focus) and recompose the shot to how you want it....then fire away.

Ah, I figured it out. Wow! Can't believe everyone doesn't use this all the time. So much easier!

I had the same reaction after I learned about it at a workshop about 3 months ago. Why hadn't I found it earlier?

 

[kami]

Ok, I just set my D300s with the AF-on only option. Now all I need is a subject. The little things you learn... The only drawback I see with this option is if you let someone take a photo of you using your camera, you have to explain this little nuisance.