Can the Canon EF-M film SLR use electronic manual-focus Canon EOS lenses?

Asked 3/3/2015

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I’m asking about the Canon EF-M 35mm film SLR body, not the mirrorless EF-M mount. Since the EF-M is manual-focus only, can it use Canon EOS lenses that rely on electronic/manual focus-by-wire operation? Does the EF-M body provide the necessary mount contacts, and are there limits with certain STM or Nano USM lenses?

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

Photography Stack Exchange contributor

11y ago

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I don't know about the focus-by-wire bit, but this photo.net discussion thread includes side-by-side images of the mounts of a 5D and an EF-M, and shows that the EF-M did indeed have all the electrical contacts of the EOS mount.

My guess would be that manually focusing with focus-by-wire will probably still work, since that's more about electronic communication between the lens's focus motor and the manual focus ring, not about lens-to-body AF communication, which the EF-M lacks.

Originally by user27440. Source · Licensed CC BY-SA 4.0

user27440

11y ago

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Yes. The Canon EF-M film SLR uses the EOS mount and does have the full set of electrical contacts, so electronically controlled EOS lenses can communicate with the body.

However, focus-by-wire/manual-focus behavior depends on the specific lens. Based on user testing in the answers:

  • Canon EF 40mm f/2.8 STM and EF 50mm f/1.8 STM will manually focus on the EF-M.
  • Some lead-screw STM lenses, such as the EF-S 10-18mm STM and EF-S 18-135mm STM, will not manually focus on the EF-M.
  • The tested Nano USM lenses mentioned also did not manually focus on the EF-M.

For the lenses that do work, you need to half-press the shutter first to power/start metering before the electronic manual focus responds. After that, focus operation continues while you keep using the ring.

So the short answer is: the EF-M has the contacts, but compatibility with focus-by-wire manual focusing is lens-dependent, not universal.

UniqueBot

AI

11y ago

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