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90mm Apo-Summicron-M not apochromatic?


LarsHP

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2 minutes ago, LarsHP said:

Okay, here it goes (again):

1) I have already explained that I have seen LoCA with another M 90 Apo with an M 240.

2) For LoCA testing it doesn't matter what sensor is used - certainly when the center of the image is concerned. If the sensor-lens relation was to blame, it should be readily visible in an infinity shot wide open, but there the lens performs brilliantly.

3) My Elmarit-M shows about the same level of LoCA as the Apo.

Sorry Lars but those are just words. What is interesting in this thread, at least i feel it so, is to check if a 90/2 apo can produce the kind of aberration you are claiming about on a Leica camera. You said that you have access to an M240 didn't you. So why not shooting this superb landscape of your country with that M240 or any other Leica camera?

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8 minutes ago, lct said:

Sorry Lars but those are just words. What is interesting in this thread, at least i feel it so, is to check if a 90/2 apo can produce the kind of aberration you are claiming about on a Leica camera. You said that you have access to an M240 didn't you. So why not shooting this superb landscape of your country with that M240 or any other Leica camera?

These are words pointing to facts. Re-read my latest post, particularly point 1) if in doubt. If you don't believe what I am saying and describing, I can do nothing. If you are happy with the LoCA performance for your needs, then good for you. We have been going in circles about this long enough as I have already said, so not reason to continue.

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1 hour ago, LarsHP said:

In a private message one of the premium members with more than a decade in this forum sent me this link:

https://blog.kasson.com/the-last-word/another-medium-tele-test-summicron-loca/

The scientifically made test clearly shows that the M 90 Apo has LoCA - even stopped down. According to the reviewer, Jim Kasson, the lens needs to be stopped down to f/8 to completely eliminate LoCA. Yes, it is done on a Sony camera, but this is of no consequence for LoCA testing in the center of the image.

Sorry, a test of a Leica M lens on a Sony (or a Nikon) sensor stack is junk science. Completely useless (although as with most junk science, it impresses the ill-informed).

A sensor stack has its own "optics" - one or more overlays of glass in front of the sensor - and, with more than one overlay, an included air gap.

Since even "flat" glass refracts light - and so does air, when it interfaces with glass - the sensor cover package can easily degrade and thus misrepresent how the lens itself performs. It can add CA, or curve the field, or otherwise make corners fuzzy.

https://en.wikipedia.org/wiki/Refraction

Leica is supremely aware of this, which is why they have always used a minimalist approach to the sensor covering, ever since the M8: one piece of glass 0.5-0.8mm thick. Two refractive interfaces (front and back, A-G, G-A).

By comparison, the Nikon Z6 uses a three-layer covering (glass/air/glass) totalling ~2.5mm thick. And four refractive interfaces (A-G, G-A, A-G, G-A). It also, per Kolari (who disassemble the things for a living) uses a blurring anti-alias (AA) filter.

https://www.dpreview.com/forums/post/61762254

https://kolarivision.com/nikon-z6-disassembly-teardown/

Not sure what Sony is doing these days - but it was well-known at the beginning of the Alpha mirrorless system that those sensors produced substandard results with otherwise excellent M lenses.

If one wants to test a lens, one puts it on an optical bench and measures the light coming out directly, with no "extra" glass in the system that is not known, calibrated and corrected for the job (e.g. collimator). At worst, one uses a Leica sensor that is designed specifically for Leica M lenses. A random sensor from anyone else is poor lab equipment.

Leica recently redesigned its 28 Summicron, originally calculated "before-digital" in the last millennium, to subtly correct for the minimal effects of even the simplistic Leica sensor covers. Leica designed the S-series (and probably the SL series) lenses to make the sensor glass "a part of the optical formula" from the beginning.

But Leica does not design their lenses to be used on just any old sensor - not their job. People who "adapt" their M lenses to this or that camera do so at their own risk.

Edited by adan
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4 minutes ago, LarsHP said:

These are words pointing to facts. Re-read my latest post, particularly point 1) if in doubt. If you don't believe what I am saying and describing, I can do nothing. If you are happy with the LoCA performance for your needs, then good for you. We have been going in circles about this long enough as I have already said, so not reason to continue.

Problem is your facts are not the same as mine actually. 
What i know for facts is that:
1/ You've shown aberrations with your 90/2 apo on a Kolari mod Nikon.
2/ You did not show any aberration on a Leica body. 
3/ I did not show any aberration on a Leica body either.
4/ I've shown that the 90/2 apo can be free of aberration on a Kolari mod Sony. 
So what could be interesting is trying to replicate your Nikon experience on a Leica body but i cannot do it for you obviously.

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90 APO-M on M10-R vs 90 APO-SL on SL2. Guessing which is which won't be very hard, I don't think.

Lars, I think you've made your point, and I have to say I also don't see lct's comments as hostile, nor anyone else's in this thread for that matter. I hope you haven't taken mine as such either, because it's hard to convey light-heartedness over the internet, and I cannot help but give you a little bit of a hard time about this, because this is an amazing lens, in my opinion. Is there a better 90 APO than the M version? Yep, the SL version. I'll be "test shot" guy, so take a look at these test shots. No wiz-bang magic here in post. These are straight out of the camera with no corrections or changes in exposure of any kind. ISO 200 and wide open. I didn't even bother to look at the shutter speed because it doesn't really matter here. The difference is obvious. 

Still, the 90 APO-M is impressive, to me anyway, for all the reasons pointed out in this thread by myself and others. If you're looking to make big prints of images like the first one you posted, however, you may want to take a serious look at the SL platform so that you can use a truly perfectly-corrected 90mm f/2 -- the SL version. 

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

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vor 1 Stunde schrieb LarsHP:
vor 4 Stunden schrieb lookbook:

Which lens do you own -
Order number 11884 ?

Yes. Judging by the serial number it's probably from 2012.

Thank you for your information.
I wasn't sure whether we could be talking about the same lens.
I haven't had a better 90s myself - but I'm also a BW photographer and have a 246 monochrome.

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vor 4 Stunden schrieb LarsHP:

I agree. As earlier stated, I might sell it, but at the moment I haven't made a decision.

Well, the serious issue you are facing with your 90 Apo Summicron is that it will be hard to sell with its well-documented malfunction.

Common Leica dealers usually would charge you 195,- € plus VAT for proper waste disposal. Nevertheless, for Leica forum members I might consider making an exclusive special offer: I would only charge 95,- + VAT + shipping. 

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57 minutes ago, pgk said:

Sorry, I lost track of what anyone is trying to prove. Can someone remind me please?

With one single lens not all different types of chromatic abberations can be resolved at all distances at all apertures at different levels of sharpness at different levels of light with different types of subject matter in different shooting situations when used on different digital camera bodies.

Weren't you paying attention, 007?

:)

Philip.

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28 minutes ago, a.noctilux said:

When I used Kodachrome without any filter, hopeless snow always so blue.

My nightmares were blue.

I'm so very tempted to get out Joni Mitchell's album of the same name!...

:)

Philip.

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51 minutes ago, pippy said:

Not as bad as yellow snow...

1st man to his neighbour : "Your son's name is written in the snow again!"

Neighbour: "Come on, he's a teenager, we've all done it"

1st man: "Yeah, but it's my daughters handwritting!!"

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