Flickering issue with the Canon 100mm2.8 Macro

The problem

I was doing some test recording with my macro, for a small test project I had in mind, when I noticed the image flickering when I was focusing in and out. At first I thought it was just my eye but the issue was still there when I looked at the video playback.




Not everyone seems to have this issue (but  I am not the only one), which make the clip unusable. 

The Solution

While asking around I was suggested (by Matthew Bennett from the Cinema5D forum) to twist the lens a little bit (like if you were going to remove it) to disconnect the exposure contact and tada! It works. I was so caught in the problem that I forgot the most obvious solution. Here is a video of the “proof”, now I just need to redo all my initial takes…


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  • Photographer / Filmmaker


    If the “flickering” effect is due to the exposure shift made by the camera as the light metered changes while focusing (or zooming), you can lock the Exposure (by pressing the * button), so I should kept fixed while recording video.

    As I did read, the exposure lock must to be locked again after each video clip, because it resets.

    Best regards.

  • Photographer / Filmmaker

    Forgot to mention:

    If this is the effect you want to solve, then this method would be much easier and safer than untwisting the lens! :)

  • admin

    I just noticed that I forgot to point out that the exposure was already locked before I started to turn the focus rig so the problem was not related to exposure variation, while it looks like it was.

    As far as I know, unscrewing the lens is not dangerous if you make sure that it does not move enough to unscrew itself more and drop from the camera by accident!

  • Photographer / Filmmaker

    Yes, I meant that accident with “safer” method. But didn’t know the exposure was already locked.

    Then why the video “flickers” ? What is the real reason?
    A change in aperture made automatically by the camera?
    (in cush case the option of using an Nikon lens with aperture ring could help, but if the ISO does change automatically too, then wouldn’t be much different.)

    – I would like to know what actually does the camera to make that undesired effect? (I could’ve bet it would be avoided with Exposure locked…..)

    – Does it happen with other lenses too?

    Thanks a lot.

  • admin

    Nope, as far as I know, it only happened with my 100mm macro and I have tried most of my lenses. When asking around it seems like I was not the only person with the issue BUT not all 100mm had this issue.
    So I might send it back to Canon for maintenance as soon as I have some spare time and know that I can part with it for a few weeks.
    As for the technical explanation, we are still looking. But I since it is only happening while I am moving the focus, I guess it is something related to the focusing information that is sent back to the body (which is why the problem vanish once the contacts are broken).