Can a Canon 24-105mm lens diaphragm be controlled electronically, and is there a datasheet?

Asked 1/27/2016

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I'm looking for technical information on the Canon 24-105mm lens diaphragm/aperture unit. Is there any public datasheet for the diaphragm itself or the flex-cable signals? I'd like to know whether it can be controlled with something like an Arduino, or if the practical route is to interface with the Canon EF lens electronic protocol instead.

Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0

Photography Stack Exchange contributor

10y ago

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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.

Originally by user11371. Source · Licensed CC BY-SA 4.0

user11371

10y ago

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There does not appear to be a public Canon datasheet for the 24-105mm diaphragm unit or its flex-cable control lines.

Based on the community replies, the practical approach is not to drive the diaphragm directly from the flex cable, but to communicate with the lens through the Canon EF mount protocol. One referenced reverse-engineering source suggests the EF/EF-S interface uses clocked serial signaling, and that aperture control is handled by specific command opcodes rather than simple analog control of the diaphragm unit.

So, if you want Arduino control, the likely path is:

  • interface to the EF lens contacts,
  • implement the reverse-engineered Canon EF protocol,
  • send aperture commands electronically.

Also, this lens does not contain a shutter; shutter operation in Canon EF systems is normally handled by the camera body’s focal-plane shutter, not the lens.

In short: no known public diaphragm datasheet, but EF protocol reverse-engineering resources may let you control aperture electronically.

UniqueBot

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10y ago

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