Canoe50d

I use back botton focus and don't plan to change but I have noticed when I am shooting moving subject in AI Servo I am holding down the back botton focus botton to allow non stop re-focus. When I do that and I am shooting at the same time, I find the frames per second to slow down. If I let go of back botton the frames per second speed back up. I didn't notice it on my 5dm3 but now using the 7dm2 and the rapid 10 frames per second it is more noticeable. Is this right and if so , why does it happen. you would think that a fast frame per second camera is made for sports and or moving subject and if subject are moving then re-focus would be key. ten frames per second would also be key. Please keep response on subject and thank you in advance.

SharpShooter Loc: NorCal

Canoe, it might depend on how you have the focus lock configured. The + and - values. In certain modes the camera will actually hesitate to shoot if you've told it focus is more important than fps and it won't shoot at full fps. In the opposite the camera(you) values fps over exact focus and fires whether you have fully locked focus. I don't know if the 5lll has those features. Plus the configuration affects focus and frame rate.
The bbf doesn't do anything any different than the regular shutter button. They are the same exact function just assigned to a different button to keep you from accidentally firing off shots in case you can't control your shutter finger.
There's a lot of set-up customization. In assigning buttons, is it possible you changed a custom feature? Anyway, just some thoughts. ;-)
SS

Canoe50d

I get it. there was a custom setting on how accurate I want the focus to be. The sacrifice could be speed. ? Will look into that, thanks

davidrb Loc: Half way there on the 45th Parallel

Canoe, you will find that the highest fps is actually achieved with some sacrifice. I am familiar with the 1 Dx and it's limitations. It is advertised at 12 fps. It will also do 14 fps, but you lose AF and you get only jpeg. I shoot jpeg&RAW, and that slows down the speed. I realize there is a decrease in performance but I can not really tell the differences. 12-14??? That's fast.10?? Still fast. When you get a batch of high-speed shots in PP look at the time stamps. THAT will make you realize how fast you are operating. Isn't it fun to bitch at such incredible action? :lol: :lol: :lol:

Canoe50d

Dont feel I am losing shots but I can hear the diff in speed.

SharpShooter Loc: NorCal

Wear ear plugs!! :lol:
You'll be fine! :lol: :lol:
SS

woolpac Loc: Sydney Australia

You need to look at tracking and accel/decel sensitivity under custom functions. These modify how focus is handled and greatly affect shutter performance in terms of FPS.

big-guy Loc: Peterborough Ontario Canada

You must remember that the 10 fps is a rated max and not a given for all situations. If the camera does not need to refocus (and/or re-expose) then speed increases. BUT in the case of a moving subject, the camera will have to adjust the focus in between shots when the mirror drops back down. This will impede the speed. Fine tune your focus all you want but he preceding still stands.

speters Loc: Grangeville/Idaho

How did you configured your shutter button, when you set up your back-button? I for example set my shutter button to focus-lock, which theoretically should slow the frame rate very slightly, but I have not noticed it in my camera (M3).