Summarit 35mm f2.4 vs f2.5 aspherical difference

[UliWer]

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Is this authorized Leica blog? 

 

You may ask the admin, where he got the information he published.

 

Or you may ask Leica directly, if the older version already had an aspherical element.

 

Did you ever see results from both version in direct comparison? 

[Soheil]

The only upgrade to a Summicron would be to the Summicron 35 pre-asph

From Summarit 35mm f2.5?

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[UliWer]

No.

 

From both versions. 

[Soheil]

You may ask the admin, where he got the information he published.

 

Or you may ask Leica directly, if the older version already had an aspherical element.

 

Did you ever see results from both version in direct comparison? 

no I haven't seen the picture comparison. It would help a lot.

[lct]

It is the same lens optically i've been told and i've never seen side by side comparos proving the opposite so far. Now i have no experience with the 35/2.4 but my 35/2.5 is significantly softer than my 35/2 asph below f/4 on borders and corners and none is free from chromatic aberration. For a better lens there i would not rule out the Biogon-C 35/2.8 which has also less flare but more contrast and more vignetting than its Leica competitors. The Biogon is my favorite "slow" 35 ever though so my legendary objectivity could be faulted . 

[01af]

It would help a lot.

 

No, it wouldn't. Why comparing a lens to itself?

 

[UliWer]

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Well, two lenses being produced at different times, looking different and having different names may be worth a try to look whether they really contain the samer optical system by comparing their results.

 

Some very sceptical people might even look farther - into the MTF-Graphs published by Leica for both lenses. And - surprise! - they are different - at least the graphs for 40lp/mm. Though - second surprise - those for the older version are better - in some respects, in others they are worse. .

 

Leica does a lot to conceal identities.   

[NB23]

I prefer to see it this way:

 

The 2.5 is old school, with a Mandlerish look.

The 2.4 is new school, with a Karbe-ish look.

 

One of them has higher nano-contrast and the other has a stunningly beautiful Delta-contrast.

 

I'd definitely buy both: one for Color work and the other for BW work. And I'd switch them sometimes, depending on the Mezzo di Contrasto of a scene.

[01af]

I prefer to see it this way:

 

The 2.5 is old school, with a Mandler-ish look.

The 2.4 is new school, with a Karbe-ish look.

 

That's a silly way to see it.

[NB23]

That's a silly way to see it.

You think?

[pop]

That's a silly way to see it.

Saying isn't seeing.

[NB23]

"The Clash of the Marits"

[Ko.Fe.]

Getting new, never opened Summarit-M 35 2.5 was my only chance to get new Leica lens. It was also making more sense to me to pay for it reasonable price, because I don't pay for gear insurance.  

I have no regrets.

It is sharp from wide open. It seems to be sharpest lens I ever owned. Even comparing to some macro lenses. Here is no color fringing or other related to color problems at all.

Filter size makes sense, while 2.4 filter size does't. Why it needs to be this big for slow lens? My Jupiter-3 and Rokkor 40/2 have same and smaller than 2.4 filter size.

I paid same price for Summicron 50 v4 and it is next to no-name lens on color and bw film and digital. Boring, no character lens. Summarit-M 35 2.5 is amazing on BW film, perfect on digital and OK on color film. 

I wish they have Summarit-M 50 2.5 also made ashperical, but they didn't. Still, I might switch to it from Cron, due to better handling and hood.

The only advantage of 2.4 is the hood in the package. 2.5 has no hood in the box and it costs Leica price. And you could have 2.4 in silver. 

To be objective I must say something bad about 2.5. So, it has more distortions comparing to Jupiter-12 and aperture ring is light on clicks. But none of it bugs me. 

Honestly, I could have just this lens as the only lens and switch it between M-E and M4-2. I don't need it faster on film and for digital I'm fine with Leica TTL flash.

[Michael Geschlecht]

The 35mm Summarit - old and new - has one aspherical element

 

You can download the lensshape here: https://de.leica-camera.com/Fotografie/Leica-M/M-Objektive/Leica-Summarit-M-1-2,4-35-mm-ASPH/Downloads

 

The sheet for the "old" one didn't mark the element as an aspherical, but it was the same lensshape.

 

When it was announced the Leica Blog in this forum said:

 

 

Same Optical Design, Tighter Tolerances

No new optical design was need to achieve the bigger aperture. Leica engineers were able to increase the maximum aperture by 1/8 exposure value by tighter tolerances in the production process. The lens design for the Summarit-M 35 mm includes one aspherical lens element, the predecessor included the same lens element, but it was not mentioned in the official lens name.

https://www.l-camera-forum.com/leica-news/2014/09/leica-summarit-m/

 

 

Whoever thinks the new version is better, might buy it and be happy. Whoever wants to sell it saying it was better, doesn't tell the truth.

 

 

Hello Everybody,

 

There is a typographical error in the Leica communication provided for us by UliWer:

 

The difference in transmission between an F2.5 lens & an F2.4 lens is not 1/8 of a stop.

 

The difference is 1/6 of a stop.

 

Best Regards,

 

Michael

[01af]

The difference in transmission between an 1:2.5 lens and an 1:2.4 lens is not 1/8 of a stop. The difference is 1/6 of a stop.

The difference between these nominal values is slightly less than 1/8 stop, or almost exactly 2/17 stops.

 

The difference between the actual lens speeds, apart from possible production tolerances, is zero.

[adan]

Some very sceptical people might even look farther - into the MTF-Graphs published by Leica for both lenses. And - surprise! - they are different - at least the graphs for 40lp/mm. Though - second surprise - those for the older version are better - in some respects, in others they are worse.  

 

I just saw a 2009 video interview with Peter Karbe, in which it was discussed how Leica produces their MTF charts - actual lab tests, or based on the computer modelling/predictions (theoretical). Karbe said Leica used the computer modelling. But in the process the interviewer asked "What about the 35 Summarit - those MTF charts suddenly changed?" And Karbe responded (with a sheepish grin) "Yes. I think we did a mistake - we mixed [up] the MTF graphs!"

 

Note the interview is 2009, long before the f/2.4 version came out. So be sure you are comparing late (post-2009) f/2.5 MTF charts to the f/2.4.

 

About time-mark 8:40 here: vimeo.com/6595625

 

I notice in Leica's current lens brochures, they have now added the disclaimer "specifications are subject to change without notice." - and publish an "effective date."

Edited October 12, 2017 by adan

[Michael Geschlecht]

The difference between these nominal values is slightly less than 1/8 stop, or almost exactly 2/17 stops.

 

The difference between the actual lens speeds, apart from possible production tolerances, is zero.

 

Hello 01af,

 

The stops written on lenses are rounded off values which are not meant to be taken to be exact.

 

The 1/3 stop larger than 2.8 is 2.5

 

The 1/2 stop larger than 2.8 is 2.4

 

1/3 is also 8/24

 

1/2 is also 12/24

 

12 minus 8 is 4

 

4/24 = 1/6

 

Best Regards,

 

Michael

[luigi bertolotti]

 

Same Optical Design, Tighter Tolerances

No new optical design was need to achieve the bigger aperture. Leica engineers were able to increase the maximum aperture by 1/8 exposure value by tighter tolerances in the production process. The lens design for the Summarit-M 35 mm includes one aspherical lens element, the predecessor included the same lens element, but it was not mentioned in the official lens name.

https://www.l-camera-forum.com/leica-news/2014/09/leica-summarit-m/

 

...

 

Frankly, the above assertion has something intrinsically FUN : quickly explained as is, it sounds a sort of joke... if we want to credit Leica of saying always the truth they could have written an elaborate phrase like : "Summarit 35,as designed, has a nominal aperture of 2,44 : the first one had manufacturing tolerances that resulted into an effective aperture of 2,44 +- 0,02... we declared it as a f2,5 because there was an appreciable chance that effective aperture was >2,45.. unfair to be rounded to 2,4 ; now tolerancing is such that real aperture is 2,44+- 0,01... the standard Gaussian curve tells that chances of a real value that is correct to be rounded to 2,4 ar so high that we consider fair to declare it a f2,4 lens"...  

 

And of course... this would be anyway a questionable assertion... the f number is a pure number, a ratio of measures , and they are the MEASURES in themselves that are subject to tolerancing... and for a lens made of several elements the tolerancing of the "assembly" depends on the tolerancing of measures of single elements (roughly said,  diameters and curvature radiuses... but there is an asph...)... we can go in depth ad libitum... 

 

Anyway, changing from 2,5 to 2,4 was pure marketing... but after all, I noticed some days ago that even Intel markets at different prices the SAME CPU in the 3,0 and 3,1 Ghz clock version...

Edited October 12, 2017 by luigi bertolotti

[luigi bertolotti]

The difference between these nominal values is slightly less than 1/8 stop, or almost exactly 2/17 stops.

 

...

Makes me remember that not many days ago THIS was a very discussed matter.... (f 0,95 vs. f1..   )

Edited October 12, 2017 by luigi bertolotti

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Hallo,

Look here: Leica M

[01af]

The stops written on lenses are rounded off values which are not meant to be taken to be exact.

That's right. But you are confusing well-defined points on a scale with actual data points.

 

The aperture number half an f-stop below f/2 is 2.3784 which for simplicity's sake gets called "2.4". However when a lens' maximum aperture is given as f/2.4 you cannot derive that "exactly half a stop less than f/2" is meant. It might just as well be rounded down from f/2.35 ... or up from f/2.44 ... or whatever. We don't know.

 

Also, we don't know if 1:2.5 written on an actual lens really is supposed to mean "exactly two thirds of an f-stop below f/2," or 2.5198. It might just as well be rounded up or down from some other number.

 

So in the case of the Summarit-M lenses, all we can do is to take the nominal numbers literally, and compute the difference, in f-stops, between 2.4000 and 2.5000. And that's 0.117787, or about 2/17, or slightly less than 1/8 f-stops.

 

Of course, that's just some pointless academic exercise, as we already know that "2.4" and "2.5" aren't really meant to be taken literally. Neither are they supposed to mean, "half or two-thirds of an f-stop below f/2, respectively". Instead, they both stand for basically the same actual value which probably is somewhere close to 2.44 or thereabouts.

 

Edited October 12, 2017 by 01af