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    Patent: Canon speedbooster for EOS M

    By 72 Comments1 Min Read Canon Patents
    eosm50big 728x462 - Patent: Canon speedbooster for EOS M

    It looks like Canon is developing its own speedbooster for EF lenses on the EF-M mount.

    Canon News uncovered a patent last week that showed Canon was looking at a new EOS M adapter, and again this week, a new patent showing the concept in more detail has emerged.

    Japan Patent Application 2018-189864:

    This patent application is for a converter that takes EF lenses and reduces the focal length and decreases the aperture all at once.

    The example in this patent applications shows a 50mm f/1.4 lens (full frame) with a back focus of 39.80 (EF full frame) and converts the lens to a 40mm f/1.2 with an image height of 13.66 and an 18mm back focus, which would work for EOS M cameras.

    If Canon is indeed going to keep the EOS M line around, developing a speedbooster for the system would be quite a nice addition to the lineup.

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    72 comments

    2. Could also be a possibility for an APS-C EOS-R camera. The R mount has a flange distance of 20mm, the M 18mm. So if they designed it for the R, all they would have to do is swap out the mount and add 2mm for the M.
    3. If Canon is indeed going to keep the EOS M line around, ...
      Could also be a possibility for an APS-C EOS-R camera.

      lol. you guys don't give up ... but .. Canon APS-C = EOS M. I don't see an "if" here.

      I would likely buy an original Canon speedbooster for EF lenses on EF-M. :-)
    5. Not with this design, but there's no reason why Canon couldn't design an RF -> EF-M speed booster if they really wanted. It'd be the only way to adapt RF glass for EOS-M bodies.
      I am not sure how you make a lens have 22 extra mm at minimum to adapt an RF lens. The registration distance of RF is 2 mm less than the M, and I can't see any adapter robust enough to hold a RF lens that would be less than 20mm deep, especially if it has to have some optics that increase the registration distance like that.
    6. An interesting idea - and not far-fetched at all. There's enough room in the EF to M adapter to incorporate lens elements that will shorten the focal length as suggested. And without changing the physical characteristics of the aperture (diameter), the shorter focal length with the same aperture diameter = a lower numerical (larger) f/stop.

      Mathematically, say you have a 50 f/2 lens. If you were to shorten the focal length, optically through the adapter, you could have, say, a 25 mm f/1 lens. Why? An f/2 50 mm lens has a 25 mm aperture diameter (focal length/2). That same 25 mm aperture on a 25 mm focal length lens would become an f/1.

      Now, I'm sure that a 2:1 lens adaptation would be kind of extreme, but something like a 1.25:1 or 1.4:1 shortening ratio would be less prone to problems.
    8. I could have sworn that a speed booster rumor was already reported back when the first M was released. At the very least, I remember reading that Metabones was looking into a design. I just figured that there was never enough possible buyers for it to seem worth releasing.
    9. An interesting idea - and not far-fetched at all.

      well, in case you are not aware, "speedbooster adapters" exist as real products for a number of years already.
      http://www.metabones.com/products/?c=speed-booster

      Only interesting question is, why neither Metabones nor Canon have not already launched an EF / EF-M speedbooster long ago.

      And if Canon also charges €/$ 649 like Metabones, then I'll pass. My idea is €/$ 199 max. But Canon being Canon, they may well bring a white-paint EOS "L" speedbooster at 999 :p:D
    10. I could have sworn that a speed booster rumor was already reported back when the first M was released. At the very least, I remember reading that Metabones was looking into a design. I just figured that there was never enough possible buyers for it to seem worth releasing.

      well, the issue i see is Metabones pricing: 649 per click will for sure seriously curb demand. :-)
    13. thx for the Viltrox speed booster info - just found it myself too, was about to post about it.

      Now it is clear to me, why all of a sudden Canon/Metabones also want to get in on it. "Innovative" Canon always needs somebody else doing it first, before they also become "innovative" ... in due course ... :-)
    14. How about an 85 f/0.9? Given the sizes of the Canon APS-C and FF sensors, it is mathematically possible to make a speed booster give 1-1/3 stops of "improvement". It's a tight fit and I imagine that there would be significant vignetting and distortion at the edges.

      Off topic, I really wish that Canon would drop the price of the EF-M adapter by about 2/3. It's just an extension tube and costs twice as much as the EF-RF basic adapter, which almost certainly includes electronics.
    16. Great idea for soaking up all the future free EF lenses if/when owners move to EOS R. Also will encourage 'upgrades' from old EF body cameras to new EOS-M bodies. A much more dynamic market offering to keep customers Canon.
      :) i love the idea of finding more light that a lens previously had possible.
    17. I am not sure how you make a lens have 22 extra mm at minimum to adapt an RF lens. The registration distance of RF is 2 mm less than the M, and I can't see any adapter robust enough to hold a RF lens that would be less than 20mm deep, especially if it has to have some optics that increase the registration distance like that.

      Speed boosters have lenses in the optical path, so it is possible to deal with this situation.
    18. thx for the Viltrox speed booster info - just found it myself too, was about to post about it.

      Now it is clear to me, why all of a sudden Canon/Metabones also want to get in on it. "Innovative" Canon always needs somebody else doing it first, before they also become "innovative" ... in due course ... :)

      Funny.

      Except that Canon originally filed the patent application back in 2017.
    19. hmm, if this makes it to the market, it could mean that Canon sees no reason to make specialised fast lenses for EOS-M, just get the booster and slap an EF lens on. But how long will EF lenses live, when RF takes of ....

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