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Which Lens to use, the R or the M?

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I have a question with regards to the size of a Lens.

I have a number of both R and M lenses of same focal lengths, which I mount on either an R or M Camera, but when needing fast feedback on my Sony a7R2 too.

So the question for the Sony is, do I use the R or the M Lens, say e.g. for a 50mm Lens when I have both types. I mean there a big difference in size, and

weight of course, but which is best? Does the R get "more" light than the M due to the R's larger size, or is a 50mm a 50mm Lens and it doesn't mean a thing i.e. no difference in performance?

Thanks

Preben

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Posted (edited)

For any two lenses of the same focal length, the one with the lower f/ ratio will accept more light.  If both lenses have the same f/ ratio (eg., if they are both Summicrons--i.e., f/2), then they will have the same light gathering power.

Edited by bcorton

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bcorton is exactly right.

But - there are a variety of "50 Summicrons," for example, for both the R and M, so one or the other may be better in ways other than light-capturing ability, just depending on when each was designed and made (after all, M lenses have been made in several models over 65 years, and R lenses were made, and sometimes redesigned, for over 40 years). One lens may be sharper at the edges than another, but not quite as sharp in the center. A particular R lens may be better focused closeup than an M lens (since the R cameras allow closer focusing, the design may be adjusted to favor that) - but not necessarily better at landscape distances. M wide-angles are often better (no optical compromises to clear the swinging mirror in the R cameras) - but not in every case.

A few R/M lenses are identical in both mounts, at least if produced in the same era (some 50 Summicrons or 135 Elmarits overlap, the 90 APO f/2 in either mount is the same glass, etc.)

R lenses are larger because they have an extra mechanism to stop down the lens only for the moment of exposure. That function won't work on non-R bodies, so its just excess size. Some lenses are made in one size or another just to keep a consistent filter size, not due to actual aperture.

If you have a specific R/M pair in mind, (e.g. 50mm Summicron R 1968 vs. 50mm Summicron M 1980, or 28 Elmarit R 1994 vs. 28 Elmarit M ASPH) someone here with experience with both can probably comment on how they compare.

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Something I thought of with respect to the Sony, some M lenses don't play well with non-Leica digitals. R lenses on the other hand usually play perfectly.

I have an old 50mm Summicron collapsible M, and a couple of 50mm Summicron R  lenses (V1 & V2), plus a 50 Distagon f4 Hasselblad. One of these days I'll line them all up on the SL and try them, just for fun. In my case, the Distagon only gets used on the Hassy, the 50mm M on the M3, and the two 50mm R lenses on the Leicaflex SL. But on my SL the 50mm M gives a nice dreamy portrait, the 50mm R V2 gives me nice and sharp, and the 50mm R V1 gives me decent close up with the Elpro's I have, what's not to like?

Gary

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I use R-lenses on my Sony APS together with a Metabones lens booster. 

My Summicron 50mm acts as a 75mm f/2 or as a 50mm f/1.5.

Of course I don't use the combination booster+extender (to achieve a focal length of 100mm). ;) 

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I use some R and M lenses on a Sony A7, and even on 50mm Summicrons I find the R does better on the edges. With 90 & up I see no difference, but on wide angles the R are clearly cleaner at the sides and corners.

But on the small bodies the M lenses, with shorter adapter, certainly handle better.

Among my SLR lens collection the small Pentax M series lenses handle best on the A7, and some - like the 20mm f4 do very well.

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When I had the Sony A7, I found that of all the 10 M lenses I had only three worked as well as they ought to on that body. Of the 15 R lenses I had, there were problems with the 15, 19, 24 and even 35 mm lenses. When I bought the Leica M-P 240 and tested the same lenses, there were no problems. And the same has been true for the SL and CL. 

I sold the Sony. Never really liked shooting with it anyway ... truly crappy shutter, weird menus and controls. 

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20 hours ago, adan said:

bcorton is exactly right.

But - there are a variety of "50 Summicrons," for example, for both the R and M, so one or the other may be better in ways other than light-capturing ability, just depending on when each was designed and made (after all, M lenses have been made in several models over 65 years, and R lenses were made, and sometimes redesigned, for over 40 years). One lens may be sharper at the edges than another, but not quite as sharp in the center. A particular R lens may be better focused closeup than an M lens (since the R cameras allow closer focusing, the design may be adjusted to favor that) - but not necessarily better at landscape distances. M wide-angles are often better (no optical compromises to clear the swinging mirror in the R cameras) - but not in every case.

A few R/M lenses are identical in both mounts, at least if produced in the same era (some 50 Summicrons or 135 Elmarits overlap, the 90 APO f/2 in either mount is the same glass, etc.)

R lenses are larger because they have an extra mechanism to stop down the lens only for the moment of exposure. That function won't work on non-R bodies, so its just excess size. Some lenses are made in one size or another just to keep a consistent filter size, not due to actual aperture.

If you have a specific R/M pair in mind, (e.g. 50mm Summicron R 1968 vs. 50mm Summicron M 1980, or 28 Elmarit R 1994 vs. 28 Elmarit M ASPH) someone here with experience with both can probably comment on how they compare.

I agree completely. My own experience is that for a similar lens etc, I find that the M lens is sharper at the widest aperture .... get f/4 or 5.6 and they look the same....note this is impression and not a scientific analysis. Also, as you note, the M lenses have a smaller form factor and feel better on, for example, my Leica CL (new digital). So I would presume the same for the Sony.

 

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Thanks all for your feedback!

Both my M and R Lenses are of the '70s vintage. M early, R later in the '70s, so maybe not to much difference in designs, etc.

I'm going to Europe and would like to "travel light" so I think that the 50mm M with the small adapter "wins", over the Metabones/R Lens which is pretty heavy. I used the R3 with my 50mm Summicron for almost 30 years so I think the light M combo will work fine.

I have been taking Photos with both the M&R the last year and got satisfactory results, in my own opinion, otherwise, it's the man behind the camera that's at fault 🙂

Once more thanks all

Preben

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Posted (edited)

With M lens (Summicron 50mm), changing aperture is a bit easier when I have it on A7R Sony.

But with R lens focussing is easier with a bit larger/fatter ring and focus to 50cm (only to 70cm with M lens).

Sometimes this 20cm less can make a picture better "framing/closer" or not depend on demand, when I don't want to carry/use Elpro or Macro-Elmarit-M.

Edited by a.noctilux

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If you are limiting the discussion to the 50mm focal length, then either the M or the R should perform about equally. But with regard to 35mm and wider, M lenses can be problematic on A7x cameras, because of the thick coverglass on the Sony sensor. Wide angle R lenses do not have that problem, though there may be variability depending on the particular lens in question.

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1030/5000
 
 
 
That is a nice issue. Two things seem important. All wide-angle lenses for SLR are retrofocus lenses because the rear lens section must leave room for the flip-up mirror. The light rays fall on the film / chip at a less sharp angle. These are the R lenses. For the M lenses, that construction was not necessary because film still accepts very skewed rays of light. This is different for digital chips. Leica had to use a chip with lenses to correctly capture those skewed light rays. A thick layer of glass or moiree filter over the chip makes that even more difficult. Hence the smaller chip and the thinner glass over the chip in the M8.
Now that digital is the norm, image errors cannot be corrected optically but also with software. Leica apparently does that with the newest M lenses since the M8. Sony et al. cannot take this into account. Therefore, the wide-angle R lenses will perform better on non-Leica devices than the wide-angle M lenses
 
 
 

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Leica R lenses are more 'telecentric' than Leica M lenses because they are further from the image plane (to enable use of the reflex mirror) … thus R wide angle lenses' images, focus on sensors at a less obtuse angle … hence less edge distortion. 

dunk 

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I agree with Dunk. Because the R lenses are "retrofocal" the exit pupil of the lens (the theoretical point from where the light rays diverge) is further from the imaging surface. Especially for wide angle lenses on a digital camera, which is known to struggle with wide rangefinder lenses, like the Sony A7 models, the R lenses with their less acute ray angle will probably work better than the M lenses. The most extreme example of this would probably be the 21mm Super Angulon-M against 21mm Elmarit-R. The R lens would I think be a noticeably better performer here. Some of the more modern M wide lenses are retrofocal, e.g. the WATE 16-18-21 and 18mm Super Elmar M (SEM).

Once you get up to 50mm, I doubt that it makes a whole lot of difference between M and R. If you are looking at the faster Summilux lenses, the final Summilux R 50 ROM lens is of the same era and similar design to the 50 Summilux-M Version III - e46. Both of these are excellent lenses and I actually prefer their rendition to the later 50 ASPH Summilux-M, even if it is technically superior. The 35 and 50 Summilux-R lenses are apparently, much loved by professional movie makers sadly, as that is keeping the prices very high. I would have bought one to use on my R9 and R4, if they were more reasonable. I had to settle for the 50 Summicron-R ROM version, where you can get a very nice one for about 15-20% of what the Summilux fetches. 

Wilson

 

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On 4/23/2019 at 11:51 PM, wlaidlaw said:

... If you are looking at the faster Summilux lenses, the final Summilux R 50 ROM lens is of the same era and similar design to the 50 Summilux-M Version III - e46. Both of these are excellent lenses and I actually prefer their rendition to the later 50 ASPH Summilux-M, even if it is technically superior...

 

The M-Summilux V2 (E43) and V3 (E46) have the same glasses. The difference are the sliding lens hood and filter size. 

It is a much older computation than the R-Summilux 50 E60. 

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