50mm vs. 50mm

RezaLoghme · Jun 4, 2025

I’m debating the real-world differences between the Leica 50mm Summilux-M stopped down to f/2.0 and the Leica 50mm Summicron-M shot wide open at f/2.0.

Specifically, when viewing images on a high-resolution screen at 100% zoom, how noticeable are the differences in:

Sharpness (center vs. edges)
Contrast and micro-contrast
Bokeh quality and rendering
Color rendition and tonal character

Is the Summicron noticeably crisper and more clinical, while the Summilux delivers a warmer, more “organic” look? Or are these distinctions subtle enough to be negligible for most practical uses?

Would appreciate any real-world experience or sample comparisons if you have them.

Thanks!

Kodachromeguy · Jun 4, 2025

Which versions of the Summilux versus which version of the Summicron? Without specifying, you won't get useful data.

RezaLoghme · Jun 4, 2025

Ah, right. Let's say lenses of the same era of course.

wiltw · Jun 4, 2025

Few generalizations can be made, conclusions only come from objective testing data (measureing resolution at diffetrent levels of contrast).

Generalization: lenses generally perform better NOT 'wide open' but 'stopped down' -1EV or -2EV

So the Summicron wide open at f/2 performing better than Summilux stopped down to f/2?...only lens testi m easurement will know for sure. It might, it might not!

Paul Howell · Jun 4, 2025

In the day lens were tested with microfiche with a LPM of around 800. As Tmax 100 at 200LPM I doubt that in terms of resolution you will see any difference between the 2, the more modern of the 2 may have better coating, less flare and improved contrast.

Don_ih · Jun 4, 2025

RezaLoghme said:
I’m debating the real-world differences between the Leica 50mm Summilux-M stopped down to f/2.0 and the Leica 50mm Summicron-M shot wide open at f/2.0.

There are no real-world differences. In the real world, lenses are used to take photos. Same focal length at same aperture is 100% the same in the "real world".

RezaLoghme · Jun 5, 2025

Don_ih said:
There are no real-world differences. In the real world, lenses are used to take photos. Same focal length at same aperture is 100% the same in the "real world".

Ok I am deciding between the two lenses, but as I dont really need the large aperture with its small DoF...maybe the -cron is "good enough" then.

RalphLambrecht · Jun 5, 2025

RezaLoghme said:
Ok I am deciding between the two lenses, but as I dont really need the large aperture with its small DoF...maybe the -cron is "good enough" then.

definately good enough. I don't know exactly how this works with Leica lenses but I always felt that my Nikon 50mm f/2 was just a little sharper wide open than my Nikon 50mm f/1.4 at f/2 but ,in any case, hardly any difference.

RezaLoghme · Jun 5, 2025

Picking the -cron instead of the -lux does not earn you any bragging rights on forums though.

grain elevator · Jun 5, 2025

In many systems, the faster lenses are intended for reportage and as such may have a less even plane of focus, more fall-off in light and sharpness, (very often) more distortion, or compromises on other such metrics, compared to the slower ones. I'm not sure about the specific lenses you mention, but these are factors to research and consider.

RezaLoghme · Jun 5, 2025

Given that I mostly shoot with zone focusing and often stop down for depth of field control, I’m starting to think I might not need the faster Summilux after all.

The Summicron at f/2.0 or stopped down will likely deliver everything I want in sharpness and character, especially for street and documentary styles where precise focus at wider apertures is less critical.

Would love to hear if others have felt the same—has zone focusing made you question the value of faster lenses like the Summilux?

grain elevator · Jun 5, 2025

RezaLoghme said:
Picking the -cron instead of the -lux does not earn you any bragging rights on forums though.

Oh and it absolutely does. Some of us lowly plebs use non-leica lenses, you can feel superior to us even with a lowly Elmar.

Saganich · Jun 5, 2025

I don't think this way anymore about lenses that have been kicking around the world awhile because lenses can have idiopathic issues introduced over the years while others seem to improve with age and 'to death do us part'... you can't tell until you work with them awhile. I've had a few 50 Lux and Cron's over the years all from the same era because I like the 0.7m focus and adjust my RF to suite and not two were the same regarding the list specified in the OP. I will say that IMO the 50 Lux's with built in hood has a bit more contrast than the 50 Cron with external hood. In the real world... exemplary example of either lens are harder to get then you think and if you find one you will be happy nailing the focus at F2 and won't care about anything much else.

RezaLoghme · Jun 5, 2025

Lenses "seem to improve with age"?

RezaLoghme · Sep 3, 2025

NOw I have got both. One has to go - if you must know, I picked up the -lux for 50% of what I paid for the -Cron. Slightly more used exterior, but thats all to complain about.

Besk · Sep 3, 2025

If the size of the -lux is not problem I would keep it now that you have it.

Just like a 20mm lens in my case - I tend to use an extra wide lens only because the extra coverage is needed.
With the extra stop of the -lux --- when you really need the extra speed it is indispensable.

chuckroast · Sep 3, 2025

grain elevator said:
Oh and it absolutely does. Some of us lowly plebs use non-leica lenses, you can feel superior to us even with a lowly Elmar.

Ha!

I had a collapsible LTM 50mm 'Cron on my IIIf and I so tried to love that lens.

But I never liked the resulting look of that particular lens. I even had it cleaned, and it still didn't deliver what I wanted. It was very sharp but lower in contrast that I prefer.

I switched to a 50mm f/2.5 LTM Color-Skopar and never looked back. I did this because I was so impressed with my 21mm f/4 LTM Color-Skopar which is just terrific with everyting I've thrown at it. I figured if they knew how to make 21s they probably made a good 50. I wasn't wrong.

Oddly, I also have 50mm f/2 V3 'Cron in M mount that is terrific in pretty much every way. So, I don't know if I just happened to get a lower contrast LTM 'Cron or if all the lenses of that generation had that look.

I did hang on to an uncoated 1945 50mm f/3.5 Elmar. It is a solid tack sharp performer - again with somewhat less contrast than I like - but it's real virtue is that the lack of coating makes it "bloom" around light sources which is a really cool visual effect.

xkaes · Sep 3, 2025

RalphLambrecht said:
I always felt that my Nikon 50mm f/2 was just a little sharper wide open than my Nikon 50mm f/1.4 at f/2 but ,in any case, hardly any difference.

The same with my Minolta lenses. My 50mm f2.0 Rokkor-X doesn't have as much glass in it because it doesn't need as much, but my f1.2 lens has to have more elements to try to correct for more aberrations. I only use the f1.2 lens when I might need it in low light situations. The f2.0 is MUCH smaller & lighter and produces slightly better results.

chuckroast · Sep 3, 2025

xkaes said:
The same with my Minolta lenses. My 50mm f2.0 Rokkor-X doesn't have as much glass in it because it doesn't need as much, but my f1.2 lens has to have more elements to try to correct for more aberrations. I only use the f1.2 lens when I might need it in low light situations. The f2.0 is MUCH smaller & lighter and produces slightly better results.

The thing is, there is so much more to perceived sharpness than lens performance, it's kind of hard - at least for me - to get overly concerned about it.

The resolving power of the film, the manner of processing, the contrast of the final image, the magnification ratio that produced that issue (or digital cropping if you insist and viewing distance all play significant roles in what we think of as "sharpness".

Moreover, if we're talking about 'Crons and 'Luxes we are almost certainly talking about handheld shooting. The best razor sharp lens and aperture combo isn't going to save us if we're shooting at 1/15. In fact, I doubt anyone is actually all that stable to be able to shoot to the performance of one of those lenses below about 1/125.

I highly recommend Thornton's "Edge Of Darkness" where he covers these matters really well.

RezaLoghme · Sep 3, 2025

As I love XP2, I should also re-think that for maximum sharpness.

cliveh · Sep 3, 2025

I have used both and as Don_ih points out, there is no real world difference. However, for me the Summilux has somethething of a universal perfection that I can't put into words.

brbo · Sep 4, 2025

There is no dilemma if you don’t need the speed. Choose the smaller/lighter/better ergonomics lens.

Oldwino · Wednesday at 9:34 AM

I have a collapsible Cron (1956) and an early version 2 Summilux (1961). They are wildly different lenses, and in my opinion, not interchangeable.
The Cron is lower in contrast, but very sharp across the entire field, even at f2. Out of focus areas have a distinctive Summicron-look (not super smooth, but not unpleasant). Quick focusing.
The Summilux is centrally sharp, with a drop-off in the mid-field. It gets sharper at f2-f2.8, and by f4 it is as sharp as the cron at the same aperture. Contrast is a little higher, but just a little. Out of focus is really lovely.Focus is slower with a longer throw. I prefer the color rendition out of the Summilux by a small margin. Also, there's a dimensionality to the Summilux photos that the Cron doesn't have.

chuckroast · Wednesday at 9:43 AM

Oldwino said:
I have a collapsible Cron (1956) and an early version 2 Summilux (1961). They are wildly different lenses, and in my opinion, not interchangeable.
The Cron is lower in contrast, but very sharp across the entire field, even at f2. Out of focus areas have a distinctive Summicron-look (not super smooth, but not unpleasant). Quick focusing.
The Summilux is centrally sharp, with a drop-off in the mid-field. It gets sharper at f2-f2.8, and by f4 it is as sharp as the cron at the same aperture. Contrast is a little higher, but just a little. Out of focus is really lovely.Focus is slower with a longer throw. I prefer the color rendition out of the Summilux by a small margin. Also, there's a dimensionality to the Summilux photos that the Cron doesn't have.

I also found the collapsible 'Cron to be very sharp but low in contrast.

Are your observations in context of film and/or digital?

RezaLoghme · Thursday at 1:35 AM

I have now bought a Summilux-R which I am also using on my M. Have yet to take pics with it.

50mm vs. 50mm

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