Sometimes, without noticing, probably when pulling the camera out of the bag or inserting it, the diopter knob turns by accident and gets the viewfinder out of focus, and ruins by that the manual focusing for me. Is there a way to permanently disable/fixate the diopter knob on pre-set value? Or it has to be a habit of checking the knob position every time I start shooting? Thanks.


Can you put a small piece of gaffer's tape over it? Should be easy to cleanly remove when you want to. For some controls I've used a dab of hot glue, sometimes with a piece of teflon tape covering the knob surface itself. If you build up some glue against the teflon tape, then remove the tape, you can sometimes create a "semi-protected" state where it can still be actuated if you need to, but doesn't happen accidentally.

  • 1
    The gaffer tape is a pretty nice hack and I think it will work fine. flickr.com/gp/alexbabi/R54E0m – alechko Jun 11 '16 at 6:16
  • @alechko It's a good look, welcome to the junkyard club! If the tape seems to get messed up by the inside of the bag, cutting the corners off can help, as well as keeping the edges in low-profile areas generally. – junkyardsparkle Jun 11 '16 at 18:51
  • thanks, it was just a test, I've already re-applied the tape, I did better cuts and cleaned the camera area with a bit of alcohol to make it stick better. works great. – alechko Jun 12 '16 at 6:30

I just started having this problem when putting my camera in and out of a Aquatech rain covering. I have a Canon R-5, so they do not make an eye-piece for it. I had to take the stretchy hole where the eyepiece goes and stretch it around the existing eye-piece. When doing that, the diopter moves. I decided to try the tape method. I used a duct tape that is not extremely sticky, and cut it to fit. Another idea would be to put a tiny dot of colored nail polish on the correct setting, so it would be easy to line up if it moves.


You could remove it altogether.

  1. Set the diopter wheel at the adjustment you desire.
  2. While holding the adjustment wheel to prevent moving it use a (correct size & type) screwdriver to remove the screw in the center of the wheel.
  3. Lift the wheel straight out of the housing.
  4. Replace the screw to close up the opening.

If you don't want to do anything that drastic and you don't currently have an eyecup attached to the viewfinder get one and place it on the camera. It will partially protect the diopter adjustment wheel from inadvertent movements. Check your User's manual to see which size your particular camera uses. Most Canon EOS DSLRs use either the Eb, Ef, or Eg size and are relatively cheap. You can get third party substitutes at very low cost. Some of the knock-offs have been reported to be larger than the OEM part and completely block the diopter adjustment wheel.

  • I tried to remove the diopter knob, but there's a pretty huge empty space left after removing it, there's no way I would return the screw back because it sticks out and it might bend or something when using the camera, I'd rather fill it with half of foam ear plug or something similar, I would not want that empty space to be left exposed. I do use the original eye cup, I believe it the Eb model. – alechko Jun 11 '16 at 5:50

Is there a way to permanently disable/fixate the diopter knob on pre-set value?

I doubt it. The knob seems to be mechanical, and there's nothing like a "locked" setting. I don't think you'd want to remove it entirely because you'd have no way to fix it if it ever went out of adjustment, or if your eyes change. Perhaps the best solution is to arrange your camera bag so that the camera isn't jammed in there too tightly, or change the orientation of the camera in the bag. I've had the same problem you describe, but only when the back of the camera rubs against the wall of the bag. It's never an issue in a messenger-style bag where the camera goes in with the back facing up.

Or it has to be a habit of checking the knob position every time I start shooting?

It's a very quick thing to check -- when you look through the viewfinder, just try to notice if the displayed data (shutter speed, aperture, etc) is sharp or not.

  • I have 2 bags, one is snug fit, one is loose fit, it happens to me with both bags, so not sure if changing bag would help me much. I guess I could have another habit of something to check every time, but I was hoping there would be a way to lock it, and if I ever needed to unlock it. I do think the gaffer tape hack suggested by @junkyardsparkle could help me do that. – alechko Jun 11 '16 at 5:53

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