EOS 7D autofocus doesn't hold target

[stockdizzle]

Noob here.  I've read the manual and checked Google as much as I can, but I'm unable to solve this simple problem.  Just bought a used 7D and can't seem to figure out how to have it stay locked on a target as I recompose the shot.  When I half-depress the shutter button it focuses, but when I move the target it changes focus to whatever else was in that focal area.  I've tried going into 'C.FnIII: Autofocus / Drive' (sub menu 6) and checked (enabled) all the options (both the square box, and bullseyed square box on right), but it still isn't locking focus.  Phase Detection is enabled.  What am I doing wrong here?  It is my understanding that the bulleyed square targets are cross-type sensors (Canon's more advanced, precise focusing technology), and that was my initial intent--to be able to select a focal point, lock it, then recenter and compose the shot.  Please help--thanks!

Canon EOS 7D (original--not Mark anything)

Canon EF 85mm f/1.8 telephoto lens

[stockdizzle]

So this is my first forum post and I hope I'm replying to the entire thread here.  Thanks for your help!  I forgot to mention earlier that I'm using this 7D on AV mode, if that clears up anything.  I read up on back-button focus and I had actually turned it on already (I just didnt know the name of it!).\  Been messing around and it defintely does do what it's supposed to do--all seems normal.  That said, I wonder why it wasn't doing this earlier.  I just bought this camera in used condition and it wasn't as clean as promised, so being my first DSLR I'm hoping it's me and not a faulty camera, especially if this happens again after the thirty day return period 🙂  

I'm going to keep this thread open for a few days so see what happens on my end, and to get any other feedback.  Thanks guys!  

Such an awesome camera!  

[Skirball]

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@stockdizzle wrote:
Thanks for replying. Yes, the camera is re-focusing while I have the shutter half-pressed, which is why I'm confused. I will read up on back button focus. Maybe there's some setting I have to change, but that seems weird since I'd assume this functionality to be set as default.

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I had to check... never know who you're talking to on these forums.

Yes, that's not standard behavior.  You can try a factory reset, just to be sure.  Otherwise, I'd suspect the shutter button.  I assume the 7D was used?

Regardless, give back button focus a try.  Those that use it absolutely love it.  Only problem is that you can't use it with remote triggeres.  It's a deal breaker for me, but like I said, many use it and love it.

If you're used to handing off your camera to others, even if it's just on occasion, it's best to set up a custom function without back button focus.  So others can figure out how to use your camera.

[RobertTheFat]

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@stockdizzle wrote:

Noob here.  I've read the manual and checked Google as much as I can, but I'm unable to solve this simple problem.  Just bought a used 7D and can't seem to figure out how to have it stay locked on a target as I recompose the shot.  When I half-depress the shutter button it focuses, but when I move the target it changes focus to whatever else was in that focal area.  I've tried going into 'C.FnIII: Autofocus / Drive' (sub menu 6) and checked (enabled) all the options (both the square box, and bullseyed square box on right), but it still isn't locking focus.  Phase Detection is enabled.  What am I doing wrong here?  It is my understanding that the bulleyed square targets are cross-type sensors (Canon's more advanced, precise focusing technology), and that was my initial intent--to be able to select a focal point, lock it, then recenter and compose the shot.  Please help--thanks!

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Sounds as though you have your autofocus mode set to "AI Servo". See p. 88 of the 2012 edition of the 7D instruction manual.