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Occasional Contributor
Posts: 22
Registered: ‎04-04-2018
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Achieving AF on some EF/EF-S lenses on EOS M or M5

p 123 of the EOS M manual states

  • With some EF lenses (Mount Adapter EF-EOS M required), it may take longer to achieve focus or correct focus may not be achieved. For the latest information, visit your local Canon Web site.

I found an knowledge base article titled "With some EF lenses, it takes long to achieve focus in AF. Or correct focus may not be achieved (EOS M)" at this site. (Doc ID ART137913). I presume this is what the manual is referring to.


For the EOS M5 which I am intersted in getting, the manual statess on p. 77

  • Focusing may take longer or be incorrect when subjects are dark or lack contrast, in very bright conditions, or with some EF or EF-S lenses. For lens details, visit the Canon website.


  1. I cannot find a similiar knowledge base article for M5.  I want to make sure that some EF lenses I use will not have compatibility problems with focus. I spent time on the Canon support site and this community but nothing came up.  Do you have a list of those EF or EF-S lenses?
  2. In the M50 manual, there is no mention of a similar issue. I wonder if that is because there are no problems, or because the manual that I downloaded is a simple edition without details.
Occasional Contributor
Posts: 22
Registered: ‎04-04-2018

Re: Achieving AF on some EF/EF-S lenses on EOS M or M5

[ Edited ]

I posed the question directly to Canon, and received a reply so I am sharing with the community.



1. There is no definitive compatibility list available for EF/EF-S lenses on EOS M5 as there was for the EOS M

2. But practically speaking, newer EOS M series camera bodies should work with EF/EF-S lenses.


Details copied from their reply:


We have not received updated, detailed information from our engineers in Japan about *SPECIFIC* EF or EF-S lenses, which when combined with the Canon Mount Adapter EF-EOS M, are especially prone to focus problems. The biggest issue initially was camera-related -- Servo AF on the camera basically wouldn't work with the Lens Mount Adapter EF-EOS M was attached. As you correctly note below, newer cameras have circumvented that. [edit: this was in reference to my question which is similiar to my orignial post in the community]


In informal testing and shooting with my personal sample EOS M5 and a number of EF/EF-S lenses, I have not encountered obvious problems. Again, however, I cannot be more specific about particular lenses, under what circumstances you may see abnormal performance, and so on, since we've never received formal notice of this from our engineering staff in Japan.


One comforting fact, at least in terms of inquiries from actual owners of cameras like the M5 and the Mount Adapter, is that I honestly cannot recall hearing a problem in terms of focus or image quality, since we moved past the limitation of not having Servo AF (again, limited to earlier M-series camera bodies).


Another comforting factor is the Dual Pixel CMOS AF system used in cameras like the EOS M5, M6, and M50 -- it's head and shoulders above the "hybrid" AF systems in place with first-generation M-series models.


From where I sit -- admittedly, with limited first-hand experience -- I'd say you can invest in this gear and use it effectively with pretty much any traditional EF/EF-S lenses you care to mount on it. Dual Pixel CMOS tends to work best when its Servo AF (to focus continuously on moving subjects) is matched-up with a lens having either STM or Nano USM focus drive, but even with other USM drive systems, they should work effectively under most conditions when combined with the EOS M5.


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