So which one is best R or M, when

[pridbor]

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You compare each with the same lens as e.g. A 50mm Summicron. I have just gotten an M7 and I'm looking at the 2 cameras with the same lens, observing the huge difference in the opening. Shouldn't the bigger lens be best, I.e. The R system, due to that much more light onto the same 35mm film?

 

I'm no expert in optics, hence this question which to some of you is a very obvious answer

 

Thanks in advance

 

Preben

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[Michael Geschlecht]

Hello Preben,

 

When the original Leicaflex was released in the 1960's: Leitz said that 1 of the reasons for the larger opening for the lens mount in the Leicaflex body was that the larger opening gave the lens designers more latitude when designing lenses. Since the smaller opening in "M" cameras necessitated some adjustments in lens design to accommodate the smaller opening.

 

An example of this might be the 1979 version Of the 50mm, F2 Summicron which is pretty much the same lens design optically as the second version of the Leicaflex's 50mm F2 Summicron.

 

Both lenses, interestingly, are not that different in design from the 1930's, 50mm, F2 Summar. Altho I would assume that the glasses chosen & lens coatings, etc had been improved.

 

Best Regards,

 

Michael

[dpitt]

I am not an expert, but one of the advatages of the mirrorless design and short flange distance of the M is that for wide angles, there is not much need for a retrofocus design. (e.g Super-Angulon 21 mm)

For the reflex systems, most wide angles need to be designed with retrofocus because otherwise the rear element would hit the mirror.

 

An other advatage caused by the short flange distance of the M is that lenses of the same focal length can be a lot smaller and lighter than the same for the R system.

[masjah]

These days, even for wide angle lenses, retro-focal designs are not intrinsically a disadvantage; indeed, with the advent of digital sensors it could be argued that they have certain positive attributes, since the light rays are not at such an oblique angle (which digital sensors generally prefer). I think it's better simply to lay any two lenses side by side and just compare their performances, full stop. Sometimes an M lens will win, sometimes an R; often they are simply different, and it's down to personal preference. If there is any one single factor at work, it's possibly the age of the design, but there are so many exceptions to this too.