RF to M Adapter?

Jun 13, 2012
13
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#1
Ok, I have an adapter to use my EF and EF-S lenses on my M and M50. If I bought an R I could also get an adapter to use the same lenses. The question is whether there will be an adapter to use these wonderful RF-mount lenses on M body cameras? Is it possible geometrically?

I have already decided I probably won't be buying any more EF lenses as the future looks RF and M. The eventual replacements for my 5D3 and SL1 will likely be mirrorless. But will there be a divide between the two mirrorless lines?

Mike E
 

Mt Spokane Photography

Spends too much time on this forum
Mar 25, 2011
14,823
266
#2
Very unlikely, the lens would have to sit inside a M or the adapter have some complex optics. EF lenses are the universal solution. The issue is due to the 18mm the rear of a RF lens sits from the sensor, while the M is designed for lenses to be 20mm from the sensor. Any adapter using lenses to make it work will likely be a kluge or very expensive.
 
Jul 17, 2012
81
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#3
Ok, I have an adapter to use my EF and EF-S lenses on my M and M50. If I bought an R I could also get an adapter to use the same lenses. The question is whether there will be an adapter to use these wonderful RF-mount lenses on M body cameras? Is it possible geometrically?
I don't think it could be done without optical elements and that'd mean it'd be expensive or lose too much image quality to make sense. Also it isn't clear how easy it would be to do electronically - do RF lenses work without all the extra pins M bodies have no idea how to use? If not, the adapter would also require complex electronics, driving the price even higher. So I doubt one will ever be made.

One caveat though: a speedbooster-type adapter could make sense. It would still be expensive but the price might be more palatable if you get bigger apparent aperture as extra benefit.
 
Aug 26, 2015
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#4
Very unlikely, the lens would have to sit inside a M or the adapter have some complex optics. EF lenses are the universal solution. The issue is due to the 18mm the rear of a RF lens sits from the sensor, while the M is designed for lenses to be 20mm from the sensor. Any adapter using lenses to make it work will likely be a kluge or very expensive.
It is exactly the opposite: 20mm for RF and 18mm for EF-M

The question has been asked in an interview before and the answer from Canon's representative was: "It can be done, but at the given size, the tolerances have to be extremely tight to do it". So I think what he meant was: it is not feasible.


One caveat though: a speedbooster-type adapter could make sense. It would still be expensive but the price might be more palatable if you get bigger apparent aperture as extra benefit.

A focal reducer already exits.
It works for FF EF lenses (or APS-C as well if one is intending to shoot cropped 4k on the M50)

Canon might make an own version (the patent suggests it would be 0.8x instead of 0.71x) that will cost more.
 
Sep 1, 2014
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#6
Very unlikely, the lens would have to sit inside a M or the adapter have some complex optics. EF lenses are the universal solution. The issue is due to the 18mm the rear of a RF lens sits from the sensor, while the M is designed for lenses to be 20mm from the sensor. Any adapter using lenses to make it work will likely be a kluge or very expensive.
it's the other way around: R has a flange distance of 20mm and M has 18mm so in theory you could have a 2mm adapter but it's tricky to fit any electronics inside..
 
#8
The latter is not possible, you can only use SLR lenses covering a wider sensor area with a speedbooster, there is a simple explanation here:
It's perfectly possible. RF lenses cover the full frame area, so with a speedbooster an RF lens could theoretically be adapted to compress the output down to an APS-C coverage of the EOS-M sensor. As it has optic elements to adjust light path you can work around the fact that the RF lens and EF-M mount have very similar flange distances although I'm sure it's not as straight forward as an EF->EF-M speedbooster it's absolutely possible.
 

Rocky

EOS Rebel T7i
Jul 30, 2010
873
11
#9
It's perfectly possible. RF lenses cover the full frame area, so with a speedbooster an RF lens could theoretically be adapted to compress the output down to an APS-C coverage of the EOS-M sensor. As it has optic elements to adjust light path you can work around the fact that the RF lens and EF-M mount have very similar flange distances although I'm sure it's not as straight forward as an EF->EF-M speedbooster it's absolutely possible.
All of these in 2 mm space??? Good luck to that