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lumenite
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Senior Member
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Posts: 1,207
Re: The diameters of EFM and RF mounts
jtstanco wrote:
lumenite wrote:
In my opinion, Canon's first decision as to the diameter of EFM mount was a mistake. They must have thought that the mount was good enough against M43 kingdoms or Sony E mount. Moreover they must have not been serious with mirrorless system at the moment since APS-C market has not been their main target. It seems certain that they just wanted to defend the market with the minimum effort. Finally they had to develop another mount, which is RF with 54mm diameter, while the diameter of EFM is 47mm.
Sony E mount is 47mm wide; Leica L, 51mm; Nikon Z 55mm. All of them support both full frame and APS-C sensors. Now RF appears to want to support both as well. At this moment, I think Canon had made another mistake when they released RF. The mount looks too big to be shared with APS C bodies since they have to give up small form factor. Considering Sony's latest lenses, I doubt Canon and Nikon's argument for a bigger mount. Canon must have thought that they would use RF only for fullframe and they needed a totally new, better mount for their future.
Would Canon really have chosen 54mm if they had not had EFM?
Although RF is not good for compact APSC bodies and Canon maybe has to give up EOS M, I think, however, Canon would not be able to avoid using RF for APSC bodies in the end. It is a better mount in terms of technology, and their focus has been always on fullframe market, apart from the inefficiency of keeping two mounts.
What do you think? Which of the following would be the best solution?
The RF mount is the same 54 diameter as the diameter as the EF/EF-S mount which has been used for years on both full frame and APS-C cameras. Canon did not increase the diameter of their mount when coming up with the RF mount.
So true. I missed the point. Thank you for your reminder. On the other hand, the mirrorless systems can reduce the body size thanks to the short flange distance, while there was no big difference between DSLR FF and Cropped bodies in terms of their sizes. The compactness was one of the main features of M4/3 mirrorless system and what Sony is still pursuing, I believe.
Nikon increased mount diameter to 55 mm for the Z mount from the F mount's 44 mm. This mount has a slightly larger diameter that the Canon RF mount. As you pointed out, Nikon already uses the Z mount for both full frame and APS-C.