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Does anyone know if a datasheet is available for the Canon 24-105mm diaphragm unit? I'm wondering if there's a way to use an Arduino or suchlike to control the diaphragm via the flex cable, but I can't find any specs or datasheets anywhere.

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2 Answers 2

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NB: this answer was written when the question was asking about the shutter, rather than the diaphragm. It may be deleted soon.

There is no shutter in the 24-105; almost every camera system smaller than medium format has a focal plane shutter in the body, rather than a leaf shutter in the lens. The only exception I know of is the Pentax Q system.

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  • \$\begingroup\$ Really? Huh. What exactly is this, then? youtu.be/WtsW9Hwa4UY?t=121 \$\endgroup\$
    – Bas
    Commented Jan 27, 2016 at 8:54
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    \$\begingroup\$ That's the diaphragm which controls aperture, not the shutter which controls exposure. \$\endgroup\$
    – Philip Kendall ♦
    Commented Jan 27, 2016 at 8:55
  • \$\begingroup\$ Ugh, brainfreeze. Apologies, I'll reword the question. \$\endgroup\$
    – Bas
    Commented Jan 27, 2016 at 9:03
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The best answer I could find to this by googling was a "Pick and Place" blog article where the author describes what he's discovered about the EF-S mount connections:

https://pickandplace.wordpress.com/2011/10/05/canon-ef-s-protocol-and-electronic-follow-focus/

It looks like you send signals on DIN's rising edge (DIN is the middle of the five small contacts), and controlling the diaphragm involves sending the $07$13 opcode, along with a two-digit hexcode value for the specific aperture setting you want. Opening it up to wide open uses the opcode $13$80.

I think. I could be wrong. I just did a quick google. :)

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