90mm Apo-Summicron-M not apochromatic?

[LarsHP]

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7 minutes ago, adan said:

If that settles it for you, (and if you think the first is in anyway a real "scientific source"), I wish you luck.

Your first "source" is a crowd-sourced stack exchange. It says so right at the top, "Anybody can ask a question. Anybody can answer. The best answers are voted up and rise to the top"

So about as authoritative and "scientific" as Facebook or Twitter. It is just the opinons of "anybodies" that rise to the top based on how many "likes" (👍) they get from other "anybodies."

If you have a medical question, would you 1) get the opinions of "anybodies" off the street, or would you seek out a trained, and qualified physician?

When the Tromsøysund Tunnel was built, was it engineered based on the "opinions of anybodies" from the Internet? Or was it built by trained geologists and engineers? Who didn't bother to ask for the opinions of the "anybodies?"

If it had been designed based on the opinions of a crowd of "anybodies" pulled off the street corners of Tromsø - would you want to drive through it?

Real science is rigorously peer-reviewed - it is checked and rechecked by other scientists and/or science-journal editors before it is published.

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

The Edmund Scientific article is much better.

It has been peered-reviewed at least twice: First, as material accepted and published by Cambridge University Press, and then again for re-publication by Edmund. It has two named scientist-authors, Eustace L. and Teresa D. Dereniak. Who by putting their names on the work, staked their reputations on its accuracy. They aren't "anybodies."

You can even look up their vitaes: https://www.optics.arizona.edu/research/faculty/profile/eustace-l-dereniak

But that scientific discussion says nothing at all about out-of-focus areas. The diagrams are very specifically limited only to the plane of focus (focus shift = 0)

I and others have pointed to several good sources that define LoCA as I have used the term all the time. If you go to post #177, you can see that Nikon USA define it the same way. I will not continue the discussion further regarding the semantics as my point is made repeatedly now. 

Edited May 20, 2021 by LarsHP

[LarsHP]

After we have been discussing my findings in this thread in 181 posts, I stumbled on this thread from 2017:

To summarize: The tread starter (original poster; OP) has the same issues with his M 90 Apo as I have described and obviously uses a Leica camera since the raw files are dng.

In post #5 the OP says:

"I had heard somewhere that the early APO lenses are corrected for one type of CA but not longitudinal CA, which is the type that shows up as purple fringing. Is that correct?"

In post #6 this is confirmed by the user ZHNL who writes:

"Yep, that is what 90APO does. Good news is your lens behave normal. Bad news is 90APO is not first grade APO lens. However at infinity, it is still way better than 90summarit on both PF and sharpness and it is still better than most sharp short tele lens out there in term of PF."

In post #8 ZHNL also confirms that the M 90 Apo isn't as sharp at close distance as it is at long distances.

So, even though several members here have tried to question my findings, my point about the M 90 Apo are confirmed already in the thread from 2017. 

Edited May 22, 2021 by LarsHP

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[pedaes]

16 minutes ago, LarsHP said:

I stumbled on this thread from 2017:

Always pays to do a search first.

Lars, what are you wanting here? Just recognition? The lens is what it is, you either use it knowing what you know or use something else. You will not change the fact that the APO designation applies only to the plane of focus. What happens elsewhere happens.  Correct it in pp if it bothers you. 

Edited May 22, 2021 by pedaes

[LarsHP]

10 minutes ago, pedaes said:

Always pays to do a search first.

Lars, what are you wanting here? Just recognition? The lens is what it is, you either use it knowing what you know or use something else. You will not change the fact that the APO designation applies only to the plane of focus. What happens elsewhere happens.  Correct it in pp if it bothers you. 

Several people in this thread has tried to say that my findings were wrong: my lens was faulty, it's not the lens, but the camera, it's not LoCA which causes the bokeh fringing etc. It was even suggested that I was trolling. 

Regarding what I want with my postings here is expressing my disappointment with how the lens performs regarding color fringing in the out of focus areas.

When I bought the M 90 Apo, it was for two things: 1) It is one stop faster than my Elmarit-M. 2) It would have significantly less color fringing in the OOF areas. In the latter point it failed to make a difference from my Elmarit-M. That's why I am disappointed. 

If it is easy to remove in editing, then why bother complaining, one might say. However, my experience is that it's far from easy to remove the bokeh fringing. By clicking a box in the raw converter, we can eliminate LaCA, but even though I worked meticulously with the color fringing tool in Adobe Camera Raw, I couldn't remove the green and purple (magenta) fringings in the background of the image. Having snow and cliffs mixed in the background is obviously a much more revealing subject to photograph than a mostly green landscape. 

[ianman]

49 minutes ago, LarsHP said:

"I had heard somewhere that the early APO lenses are corrected for one type of CA but not longitudinal CA, which is the type that shows up as purple fringing. Is that correct?"

"Yep, that is what 90APO does. Good news is your lens behave normal. Bad news is 90APO is not first grade APO lens. However at infinity, it is still way better than 90summarit on both PF and sharpness and it is still better than most sharp short tele lens out there in term of PF."

In post #8 ZHNL also confirms that the M 90 Apo isn't as sharp at close distance as it is at long distances.

These are all things that have been said here IIRC.

[pedaes]

1 hour ago, LarsHP said:

2) It would have significantly less color fringing in the OOF areas

OK, so that was a hope that was not fulfilled. I see your disappointment and sympathise. 

In what you want to shoot, it is going to be difficult and perhaps need to look at all options. Does a polarising filter help?

Edited May 22, 2021 by pedaes

[farnz]

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49 minutes ago, LarsHP said:

When I bought the M 90 Apo, it was for two things: 1) It is one stop faster than my Elmarit-M. 2) It would have significantly less color fringing in the OOF areas.

As explained to you repeatedly, longitudinal chromatic aberration is only corrected in the plane of focus by an apochromatic lens so your point 2 was never going to happen and you would have saved yourself disappointment if you had researched the subject before you bought your 90/2 APO-Summicron-M asph and not relied on assumptions.

I empathise with you to some degree but now you know where the blame lies.

Pete.

[ianman]

22 minutes ago, pedaes said:

In what you want to shoot, it is going to be difficult and perhaps need to look at all options. Does a polarising filter help?

Focus stacking maybe (ughhh!)

[lct]

1 hour ago, LarsHP said:

After we have been discussing my findings in this thread in 181 posts, I stumbled on this thread from 2017

Funny that the ugly pic you're showing comes from my... Summicron 50/2 apo . Don't ask me what loca/laca means i'm not smart enough to understand but what i know for facts and what i repeat ad nauseam on this good old forum is that any lens can produce color fringing even the most expensive ones. Scientific and technical explanations are out of my reach but facts are facts. Suffice it to overexpose et voilà, you got fringing. I can produce it with any lens at will. Remains true that all lenses are not equal in this regard. As far as my own lenses are concerned, i consider 90/2 apo the second best below 90/2 v2 but well above 90/2 v3. For better results among 90/2 M lenses i would pick none that i know of (90/2 v1 perhaps?) but some slower lenses do better. All this is a matter of compromise sorry to repeat it ad nauseam too.

[LarsHP]

1 hour ago, ianman said:

These are all things that have been said here IIRC.

Thanks. After reading and posting it, I do think I remember hearing that (apo = either fully LoCA or LaCA corrected) thirty or forty years ago.

[LarsHP]

1 hour ago, farnz said:

As explained to you repeatedly, longitudinal chromatic aberration is only corrected in the plane of focus by an apochromatic lens so your point 2 was never going to happen and you would have saved yourself disappointment if you had researched the subject before you bought your 90/2 APO-Summicron-M asph and not relied on assumptions.

I empathise with you to some degree but now you know where the blame lies.

Pete.

As I have also explained repeatedly have explained Nikon, I and others don't agree. It seems not to be how the term is understood by experts today. It seems to be the original sense of the term, but today all lenses will be considered apochromatic if you limit the term apochromatic to the plane of focus. This is why lens testers often use a black and white ruler of some kind in order to check for LoCA. To me, it sounds a bit like saying: This car is an "automobile". BMW, Toyota, Chrysler etc. don't use that word to distinguish their car from the competitors since it goes without saying.

As I also have written several times, the 180mm Apo-Lanthar (as well as my Costal Optics 60mm Apo Macro and Voigtländer 15mm f/4.5 VM) does not show color fringing in the out of focus area. So, I am not buying that my expectations were unjustified considering the level of perfection we expect from an expensive Leica lens. If it was a cheap, old Sigma lens which has the apo-label, then I would still have been disappointed, but not to the same degree as with a current $5000 Leica lens.

 

Edited May 22, 2021 by LarsHP

[lct]

1 minute ago, LarsHP said:

As I have also explained repeatedly have explained Nikon, I and others don't agree. It seems not to be how the term is understood by experts today. It seems to be the original sense of the term, but today all lenses will be considered apochromatic if you limit the term apochromatic to the plane of focus. This is why lens testers often use a black and white ruler of some kind in order to check for LoCA.

As I also have written several times, the 180mm Apo-Lanthar (as well as my Costal Optics 60mm Apo Macro and Voigtländer 15mm f/4.5 VM) does not show color fringing in the out of focus area. So, I am not buying that my expectations were unjustified considering the level of perfection we expect from an expensive Leica lens. If it was a cheap, old Sigma lens which has the apo-label, then I would still have been disappointed, but not to the same degree as with a current $5000 Leica lens.

Again you're comparing apples to oranges here. If you're interested in 90/2 M lenses, compare the 90/2 apo with other 90/2 M lenses not 15mm, 60mm or 180mm. Not even 90/2.8 nor 90/4.

[LarsHP]

48 minutes ago, lct said:

Funny that the ugly pic you're showing comes from my... Summicron 50/2 apo . Don't ask me what loca/laca means i'm not smart enough to understand but what i know for facts and what i repeat ad nauseam on this good old forum is that any lens can produce color fringing even the most expensive ones. Scientific and technical explanations are out of my reach but facts are facts. Suffice it to overexpose et voilà, you got fringing. I can produce it with any lens at will. Remains true that all lenses are not equal in this regard. As far as my own lenses are concerned, i consider 90/2 apo the second best below 90/2 v2 but well above 90/2 v3. For better results among 90/2 M lenses i would pick none that i know of (90/2 v1 perhaps?) but some slower lenses do better. All this is a matter of compromise sorry to repeat it ad nauseam too.

Well, I think my expectations come from when seeing the performance from some so called "true" apochromatic lenses and when the M 90 Apo didn't live up to that, my disappointment arose. Perhaps I should say that I have also seen images from several other "apo lenses" showing LoCA, and I have been disappointed with those too.

If standards are expected to be extremely high, we suffer the consequences of being disappointed... Better not have too expectations then. 😁

[LarsHP]

In order to give those who follow this thread (and supply a little more context), the attached image is the "guilty sinner" making me decide to buy the M 90 Apo.

When editing this picture I saw the out of focus areas (inserted in 100%) and basically said to myself: "This wouldn't have happened if I was using the 90mm Apo-Summicron-M, and I would even get more background separation too". Apparently only the last was true.

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Edited May 22, 2021 by LarsHP

[LarsHP]

13 minutes ago, lct said:

Again you're comparing apples to oranges here. If you're interested in 90/2 M lenses, compare the 90/2 apo with other 90/2 M lenses not 15mm, 60mm or 180mm. Not even 90/2.8 nor 90/4.

I am comparing LoCA performance, not focal length.

[LarsHP]

2 hours ago, pedaes said:

OK, so that was a hope that was not fulfilled. I see your disappointment and sympathise. 

In what you want to shoot, it is going to be difficult and perhaps need to look at all options. Does a polarising filter help?

As it is, other lens options would be non-M mount lenses, and they will be much bigger and heavier, for instance the Zeiss Otus. Regarding polarizer, I don't think it would help, but I will check it out next time just to make sure that I'm not missing an easy fix.

[lct]

12 minutes ago, LarsHP said:

I am comparing LoCA performance, not focal length.

Why would a 90/2 lens have the same CA performance as a 15mm or 180mm? Your disappointment sounds somewhat irrational with respect. You wanted a 90/2 lens in the first place didn't you. And you wanted a Leica M lens to the point that you got your Nikon sensor modded by Kolari vision for that. Then your choice was simple. Only available lenses were Summicrons and they could only be 90/2 v1, 90/2 v2, 90/2 v3 or 90/2 apo. That's all. If you had asked here i would have told you that the 90/2 v1 has a very good reputation but i have no experience with it and that besides the latter, the better lens as far as CA is the 90/2 v2. But both v1 and v2 are significantly bigger lenses. Then the better compromise would have been and still is the 90/2 apo. 

 

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[LarsHP]

2 hours ago, lct said:

Why would a 90/2 lens have the same CA performance as a 15mm or 180mm? Your disappointment sounds somewhat irrational with respect. You wanted a 90/2 lens in the first place didn't you. And you wanted a Leica M lens to the point that you got your Nikon sensor modded by Kolari vision for that. Then your choice was simple. Only available lenses were Summicrons and they could only be 90/2 v1, 90/2 v2, 90/2 v3 or 90/2 apo. That's all. If you had asked here i would have told you that the 90/2 v1 has a very good reputation but i have no experience with it and that besides the latter, the better lens as far as CA is the 90/2 v2. But both v1 and v2 are significantly bigger lenses. Then the better compromise would have been and still is the 90/2 apo.

Why would an apo designated 90mm Leica lens NOT have the same LoCA performance as another (telephoto) apo designated lens? Your point would suggest that we should expect a lesser performance from a Leica M 90mm f/2 lens than other lenses. I didn't necessarily prioritize the f/2 aperture above LoCA correction. Thought I would get both. If there was a 90mm f/2.8 in M mount with stellar LoCA control, I would probably have bought that by now (unless it was silly expensive).

Designing a lens is a matter of getting as few aberrations as possible. In that regard it's irrelevant what focal length we are discussing. I do understand that it's more difficult to design a "flawless" f/2 lens than a ditto f/4 lens. My complaints here though is not that the M 90 Apo isn't perfect, but that it doesn't control LoCA better than the Elmarit-M which isn't apo designated.

I think most people think of Leica lenses as either "the best", as cost no object choices, or at least as top quality. While the M 90 Apo is top quality in several regards, I am expressing my disappointment about what is often called "bokeh fringing" (a less troublesome name in this thread for the same as LoCA). 

I will have a look at the 90mm Summicron pre Asph and see if how it performs regarding LoCA.

[lct]

Sorry but you're still comparing apples to oranges. You can only compare a 90/2 M lens to another 90/2 (or possibly 85/2) M lens. 90/2.8 or 90/4 lenses are not the same lenses at all. The only competitor i know of is a lens even more expensive the ZM 85/2. It is bigger, cannot be found new anymore and i don't know if it is better CA wise than the Summicron apo. 

Edited May 22, 2021 by lct

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[lct]

23 minutes ago, LarsHP said:

I will have a look at the 90mm Summicron pre Asph and see if how it performs regarding LoCA

I have no idea about LoCA but my v3 has more CA than the apo. The best one, to me, is the v2 you can see above. Superb lens indeed, my favorite 90 ever. Too bad it is that big. I have already broken an adapter with it so better use a solid adapter on your Nikon.