Yes, you CAN use an EF-M lens on an EF body (sort of)

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Are you the sort of person who hates to be told you can’t do something? Like these EF-M lenses. designed for EOS-M series cameras and cannot, under any circumstances, be made to work on a EF camera body. Flange distance, electronic focus,  blah blah blah.

Well, guess what. Ok, you probably don’t have to guess because the photo makes it obvious. I stuck an EF-M lens on my 5D Mark III and made it take some photos!

Before we get to look at the quality of these photos (spoiler: I’d be showing them nearer the top of this article if they were any good) let’s talk for a moment about why it shouldn’t work.

Mirrorless lenses are designed for a very much shorter distance between the lens and the sensor than you have an in a DSLR. A DLSR has to have a big space between your optics and the sensor so there’s room for the viewfinder mirror to fit and to swing out of way.  Getting rid of the mirror means you can move the lens closer to the sensor. Not only does this make it more compact it allows you to create an equivalent quality lens with smaller and lighter optical components because the lens is so much closer to the sensor.

So. EF-M lenses are designed to work with this shorter flange distance, there’s no way they can work on a standard EF body. Is there?

Now. I have a large number of cameras and lenses. I have right now sitting on my desk in front of me a 135mm m42 lens, a 28mm Canon FD lens, a Nikon 24mm 1:2.8D F mount lens and a Sony 18-55mm E mount lens. Why? Because I’m not very good at tidying up after myself. Oh, and also because I have a large variety of cameras.

I bought the Nikon lens for a project which I will document here shortly (tilt-shift adaptor for EOS-M) and figured I might as well have an Nikon to EF mount adaptor too so I could use the lens on my 5D Mark III (although as I already have the superb Canon EF 24mm f/2.8 IS USM there’s probably not much need).

When I was doing some research previously for my article on a possible full-frame EOS M4 I noted that the EF-M mount size was almost identical to both Sony’s E mount and the old Nikon F mount. And not only is the EF-M mount pretty much the same in size as F mount, but the lens mount is virtually identical. So much so that I found an EOS-M lens fits perfectly into a Nikon F adaptor.

Here’s the adaptor fitted to the back of the EF-M lens. Note that it slides in and clicks to lock in place perfectly!

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And here it is mounted on the camera:

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Woohoo. Let’s take some photos!

Oh wait… Now, we should probably figure out that this lens is far too far away from the sensor, so there’s no way we’ll get infinity focus (a bit like when using other lenses with extension tubes). But actually it’s worse than that. We don’t get any focus at all!  That’s right, this lens has fully electronic focus so you can turn the focus ring as much as you like it doesn’t do a thing if it’s not powered up and connected to a real EOS M series body. Oh well. No focus.

Next problem – you can’t control the aperture either. That’s nothing unusual as most Canon lenses have no way to adjust aperture except electronically. but on EF-M they’re locked at the minimum aperture for some reason. Which for this EF-M 22mm f/2.0 STM lens is f/22.  So taking photos is challenging.

Here’s my first attempt. It’s entitled “Lid of Water Bottle with my wife working in the background” (C) J.Ralph 2015 All Rights Reserved

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I love the bokeh in this. I love that everything is bokeh and there isn’t anything sharp anywhere. Such a dreamlike quality. I’m not sure my wife likes her neck in this picture though.

One interesting thing to note is that even though the EF-M lens is designed for APS-C sensors at this distance from the sensor it’s filling the full frame without major vignetting.

This second one is entitled “Paper aeroplane hanging from the lounge light”. Lomotastic!

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So. The moral of the story is that sometimes, just sometimes, the impossible is possible. But then most of the time even when the impossible is possible it’s utterly, utterly pointless.

 

 

 

 

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4 Responses

  1. Jac says:

    I believe it’s to protect the Sensor on An EOS M when the camera is turned off, as there’s no mirror and the shutter is kept open.

  2. Ticho says:

    I’m interested in see this experiment with the Rokinon 12mm f2.0. That is a manual focus lens so you should be able to focus farther.

    So please let me know if you have tried it or if you wanna try it out! Curious about the results. 1 stop difference is nice to have when shooting astro (although you may rather go full frame.

    Talking about full frame, this lens was designed for max APS-C format. But I don’t see extreme vignetting in the pictures?

    • Ticho says:

      Haha now I’ve read the 3rd to last paragraph I see you noticed it too. (I had the Rokinon 12mm in mind when I wrote that)

      Still curious how the 12mm would hold up.

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