Broken aperture gear–EF 100mm F2,8 USM


This lens had a ERR99 problem – which, as we know, could be practically anything. Aperture didn’t worked.  I disassembled it, and I observed that the back lens element has broken collars in the barrel, so it was not possible the moving during focusing. This could be enough to make err99, and to stop the aperture in normal working.  I replaced the collars, and, as always, I cleaned all the lens elements, so the lens has been disassembled totally. After mounting back worked fine, I gave it back to the owner.

After two days I had a phone call – the same symptom. Hrrrrrrrrr.

I have got back the lens – and yes, the aperture was not working….. Then working. Not working…………………

I disassembled the lens, and the aperture module too (is a double one, a mechanical for the fix maximum aperture, and an electric one. As You can see, in the inside there is a small gear – which has 2 broken teethes. In fact this is a small cylindrical magnet, on which there is the small gear.

DPP_0004  DPP_0002

Unfortunately not reparable (I could take it out , but there was no donor). I only cannot understand, how is it possible to break this tiny gear?!?!?

Anyway, we should order now a complete aperture module – and I have to fix it now for free.

To acquire  knowledge no price is too high Mosolygó arc

About canonrepair

Ruzsa János. Amatőr fotós, Canon DSLR váz. Amateur photographer. Canon DSLR user.
This entry was posted in Canon lens, EF 100mm F2,8 USM. Bookmark the permalink.

4 Responses to Broken aperture gear–EF 100mm F2,8 USM

  1. Cardoso says:

    Not sure but maybe the gear from 17-85 is compatible. Again not sure. Also don’t forget the original position of the gear in the maximum aperture value!!!!

  2. Lopes cardoso says:

    Did you find the gear? I have some that could be compatible

  3. Martin says:

    Cool! You can repair this gear I think. 🙂

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