David Kay Loc: Arlington Heights IL

If my DSLR is set up for BBF, then do I have to hold that button in continuously to keep things in focus? Or how does BBF work with the video?

Bobspez Loc: Southern NJ, USA

What's BBF and what camera are you using?

David Kay Loc: Arlington Heights IL

Back button focus and a Nikon D7100

Bobspez Loc: Southern NJ, USA

I believe BBF locks the focus, overriding the autofocus. I think it only works as long as it is held down. For video I don't know if you have to hold it down to keep it locked, but it would seem you would. I guess you would have to experiment. I could see this would be useful for keeping objects out of focus as your subject comes into focus, or while you pan the camera to the subject. This technique is used a lot in movies. Another method would be to turn off auto focus on the lens and just use manual focus for that shot.

Shaker Loc: New England

I very recently got a D750 and in my menu I have set my Auto-Focus-LOck button (the back button) to be the focus activation button (instead of a half puch on the shutter button. This is usually called back-button focus.

When the camera is set for photos, the auto-focus function can be set to either C constant or S single or A auto. And the auto-focus function is great.

BUT when the camera is set for video, the auto-focus work terribly. And the S and C functions seem confused.

I have been told a number of times that auto-focus doesn't work well when using the viewing screen. I am not sure why this would be the case. BUT when I opened the box of my new camera there was a little thing-a-ma-jig in the box with instructions that I needed to place that thing-a-ma-jig over the view-finder when using the viewing screen ... other-wise light could seep somehow into the camera and confuse things. This may have something to do with it all. I'm still experimenting.

So for now I am adepting myself with using manual focus. Manual focus in many situations offers me a much broader artistic brush than auto-focus ever could.

Funny, I had a little Nikon point and shoot Coolpic P510 50x ... and the focus during video was much much better !!! go figure.

Bobspez Loc: Southern NJ, USA

Continuous auto focus on video can be a problem if the motor noise records on your audio, and you don't have a separate audio recorder. I had a Fuji HS10 bridge camera with great autofocus and auto aperture on video. But the constant motor noises and aperture clicks ruined the audio recorded on the camera.