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Similar to another question (Unknown limit switch on a commercial camera iris diaphragm) I have a few malfunctioning aperture assemblies (Canon 100-400, 28-300, 24-105) which I suspect all have the same photo interrupter. Does anyone know the article number? I want to buy a few and try to get the apertures working that way, rather than replacing the entire assemblies.

The reason why I suspect the photo interrupter:

  • Aperture only closes, never opens. In fully opened state, the photo interrupter is interrupted by a plastic piece. In all other states, the photo interrupter is not interrupted. The aperture behaves as if the interrupter is always interrupted.
  • Exchanged the photo interrupter of a 28-300 with a 100-400 - no difference
  • Exchanged PCB that operates the aperture - no difference
  • Tested aperture assembly with PCB of other lens (28-300 aperture, 24-70 PCB). The stepper motor that actuates the aperture is connected the other way around on this PCB. In this case, the aperture assembly only opens, never closes. Hence, the stepper motor does not seem to have a problem.

I have not measured the diode (yet).

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  • \$\begingroup\$ Welcome to the EE Stack Exchange. Most likely there are enthusiasts here that can answer your question, but I think you can get better responses at the Photography Stack Exchange. \$\endgroup\$
    – Syed
    Commented Nov 24, 2021 at 15:58
  • \$\begingroup\$ @Syed No, this is the site for component identification. Photography is not the site \$\endgroup\$
    – Voltage Spike ♦
    Commented Nov 24, 2021 at 16:07
  • \$\begingroup\$ @VoltageSpike: except that the OP is looking for a photography-specific component, that's probably a custom-designed electromechanical part. That would be the sort of thing that a lens geek would know, and a a circuit geek who isn't also a lens geek wouldn't. \$\endgroup\$
    – TimWescott
    Commented Nov 24, 2021 at 16:10
  • \$\begingroup\$ We can adopt the wait and see approach for a few days. If there are no responses, the moderator can always migrate it to the best SE. Thanks for your feedback. \$\endgroup\$
    – Syed
    Commented Nov 24, 2021 at 16:22

1 Answer 1

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I recently found it: Rohm RPI-121

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  • \$\begingroup\$ Laurens - Hi, Thanks for coming back with an answer to your question. In order to effectively mark the topic as solved, please consider "accepting" an answer (i.e. click the "tick mark" next to an answer - your answer or another one, if one is written - to turn the relevant tick mark green). This shows that you don't need more help and future readers can quickly see which was the confirmed solution. Thanks. \$\endgroup\$
    – SamGibson ♦
    Commented Sep 15, 2022 at 20:35

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