Apo-Telyt 135mm f/3.4 ... chromatic aberration

[adan]

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1 hour ago, BastianK said:

Only because you can show one picture with no areas of high contrast and therefore no CA doesn't mean the lens is free of CA.
It merely means you took a picture of a scene where they don't show up.

Exactly. One picture - which is representative of about 99.99% of my photos. Which are not about technicalities, but about moments and people and gestures and expessions. And generally reveal little CA, given their complexity, inherent colors, and other characteristics.

Nitnaros showed us a perfectly fine technical demonstration of what the 135 APO does regarding CA, and suitable for illustrating his question. I complimented him on how well it did that. I hope he understood that, and agrees, but I'll leave that up to him.

But yes, in the overall ART of photography throughout its history, technical excellence (or otherwise) is nicht sehr wichtig.

If you went to the Stuttgarter Philharmoniker for a piano recital, would you prefer to hear a pianist play simple scales (do-re-mi....) to show exactly how good or bad the piano tone and tuning was? Or would you think it more important to hear Bach and Beethoven and Brahms, even if performed on an only "adequate" piano?

[adan]

If my example is felt to be too limited a sampling, there are also these 135 APO photographs for consideration.

 

 

[lct]

Cropped out of my snap above. Loca, laca or no CA?

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Edited August 23, 2023 by lct

[BastianK]

vor 37 Minuten schrieb lct:

Cropped out of my snap above. Loca, laca or no CA?

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loCA

[anickpick]

Rangefinder focussing with the 135 Apo Telyt can be challenging, however, possible slightest CA should be the least of your worries. 

 

 

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[IMAGEPOWER]

vor 13 Stunden schrieb BastianK:

What kind of CA, lateral or longitudinal?

The amount of lateral CA does not change on stopping down (except for extremely rare cases) but your Nikon cameras will automatically correct these in-camera for Jpegs whereas your Leica camera doesn't.
Longitudinal CA should be very well corrected with this lens (way better than what the 135mm 3.4 has to offer).
The Zeiss lens is however one with a floating elements design, where the correct flange focal distance is crucial for optimal performance.
If your Nikon -> Leica adapter is too short (or even worse: too long) you can encounter (vastly) decreased image quality and more CAs.

How to check if your adapter is too short?
Focus at something located at infinity (e.g. the moon) and check what the distance scale reads. My guess: something closer than infinity.

To be honest, I don't care, as I moved to the APO-Telyt on my M11. The Carl Zeiss APO stays with my Nikons.

As for the adapter, it's the Novoflex LEM/NIK NT which is of very high precision, hence the price of EUR 169.00. I also use it for my Carl Zeiss lenses 15mm/f2.8, 25/f2 and 50/f2 Macro. Whereas the 15mm and 50mm show almost no CAs and if so only wide open, the 25mm shows a a higher amount of CA (also wide open only). And I am not comparing JPGs but RAWs. So if there was any internal correction of my Nikon cameras with Carl Zeiss lenses I would not profit from it anyway.

Do you actually possess the Carl Zeiss APO 135mm/f2?

[andybarton]

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OK, folks, maybe we can step back and take a deep breath here.

No need for arguments, thanks

[adan]

On 8/22/2023 at 10:14 PM, lct said:

Cropped out of my snap above. Loca, laca or no CA?

It is color fringing on out-of-focus parts of the image (just as in the picture in post #1).

Since it is in the unfocused areas, it is "undefined" as any form of CA.

Simply color fringing - not CA of any type.

The relationship between chromatic aberration and color fringing is best expressed in a logical statement, not an equation.

All visible chromatic aberrations in lenses produce visible color fringing - BUT - not all color fringing is due to a lens chromatic aberration.

Or put another way: chromatic aberrations are a subset of the various causes of color fringing. Which also include gross overexposure, other optical "flare" around silhouetted objects, leaking of light energy between silicon sensels, the subject being out of focus, and so on.

Once one has eliminated all those other possible sources of color fringing, then (and only then) can one focus on CA from the lens itself.

Longitudinal chromatic aberration - the lens has slightly different focal lengths for different color wavelengths, and is focusing them at at different distances (lengths/longitudinal error) from the lens. Result, one or two of the primary colors are misfocused and combine to produce a single-colored blur around all sides of a focused point (•) 

Lateral chromatic aberration - the lens has slightly different fields of view/magnification for different colors, which do not overlap correctly, and appear as two-color fringes on opposite sides of every high-contrast focused object, increasingly towards the sides (and corners) of the picture (lateral/latéral/lateralis error = "sideways"). The bi-colors are color complements - red/cyan, magenta/green, or yellow/blue.

((((•))))    (((•)))    ((•))    (•)     •     (•)   ((•))    (((•)))    ((((•))))

 

 

[lct]

Thank you for your commendable efforts, but I'm decidedly not intelligent enough to understand i fear. In my crop above i seem to see some leaves in focus with no color fringing, some closer OoF ones with purple color fringing as well as remote OoF branches with green color fringing. We had a good colleague here who used to explain that LoCa (longitudinal chromatic aberration) appears usually when purple fringes are before and green fringes behind the plane of focus (link). Isn't this the case here?

[adan]

If the in-focus leaves do not have color fringes, there is no CA. Period. Full Stop.

CA only exists or does not exist in the in-focus parts of the image. Out-of-focus areas of the image are irrelevant.

New subject....

There may well be color fringes in the out-of-focus areas, but those are NOT CA by the standards of optical science. OOF parts of the image are - by definition - "beyond the pale" and count for nothing in determining existence or non-existence of CA in a lens.

To say otherwise is like complaining that "My lens must be faulty - the things I don't focus on, are out of focus!"

A basic misunderstanding of what a lens is designed to achieve. A specific and singular plane of focus.

[Robert Blanko]

vor 2 Stunden schrieb adan:

…

CA only exists or does not exist in the in-focus parts of the image. Out-of-focus areas of the image are irrelevant.

…

This would mean that LoCA could never occur? 🤔

[wizard]

vor 2 Stunden schrieb adan:

If the in-focus leaves do not have color fringes, there is no CA. Period. Full Stop.

CA only exists or does not exist in the in-focus parts of the image. Out-of-focus areas of the image are irrelevant.

New subject....

There may well be color fringes in the out-of-focus areas, but those are NOT CA by the standards of optical science. OOF parts of the image are - by definition - "beyond the pale" and count for nothing in determining existence or non-existence of CA in a lens.

To say otherwise is like complaining that "My lens must be faulty - the things I don't focus on, are out of focus!"

A basic misunderstanding of what a lens is designed to achieve. A specific and singular plane of focus.

+1. Well explained and, in my view, entirely correct. APO lenses are designed to not have CA in-focus. In other words, an APO lens is designed such that all (relevant) wavelengths of light focus in the same plane, resulting in that there is no (visible) CA around the object that is in focus.

[charlesphoto99]

I've never seen anything like the OP's example with my APO. I have seen reports of increased fringing with the M11 with lenses such as the 28 Lux, so perhaps a combo of lens and sensor. But then again, I'm mostly shooting landscapes with it and my M10-R, or action type stuff with the M10M. It's a great lens, though can flare wickedly shot into a light source. Here's a recent from our balcony (full frame btw), M10M.

 

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[adan]

8 hours ago, Robert Blanko said:

This would mean that LoCA could never occur? 🤔

You'll have to clarify that question a bit.

Long. Chromatic aberration, as revealed by color fringing in the plane of focus, occurs frequently across the universe of photographic lenses, especially longer and faster lenses, and especially older ones made before relatively inexpensive aspherical lens shapes and ultra-low-dispersion glass types.

It just virtually never occurs in the 135 APO-Telyt specifically.

The 75mm Summilux from 1981 has fairly obvious LoCA at f/1.4 - color fringing in the plane of focus.

Here is an example of classic LoCa from the 75 Summilux at f/1.4. Cropped image. Plane of best focus is the farthest rim of the woman's spectacles. There are fairly obvious "red glows" around the highlights and into the shadows.

By "dissecting" the image using Photoshop's color channels independently, we can see why.

The image in green light is quite sharp in the plane of best focus. Correctly focused.

The image in red light is not focused in the same plane, so the same details are blurry, low-contrast "cotton balls" in red, and the red blurs overhang the sharp green image to produce the red fringes/glows.

The "signature" of LoCA - at least one color is not focused in the same plane as the others.

(as always, click the image, and then click again, to see the posted image as large and sharp as possible)

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Edited August 24, 2023 by adan

[Knightspirit]

Well DANG - what a thread to get your head spinning! I stumbled on this as I am looking to get a 135 - particularly the APO 3.4. In the meantime - I have already ordered a nice example of the Tele-Elmar to try first. While I am expecting a little CA from the Tele Elmar - I was NOT expecting what I saw in post #1 from the APO 3.4. I imported that shot  and tried to eliminate the two colors in Lightroom and all I got was a shot that looked like it was in black and white. Really tough to work with that kind of thing.

A lot of food for thought here...

[lct]

I don't know if it is CA or not but my 135/3.4 apo  does more color fringing than my Tele-Elmar and even my old Elmar 135/4 so i use the apo when i need f/3.4 mostly. It is also sharper at f/4.

[Knightspirit]

 

10 hours ago, lct said:

I don't know if it is CA or not but my 135/3.4 apo  does more color fringing than my Tele-Elmar and even my old Elmar 135/4 so i use the apo when i need f/3.4 mostly. It is also sharper at f/4.

Here's the phenomenon you saw - I don't think I saw this term mentioned in this thread - but I didn't read all of it:

"Spherochromatism, also called "color bokeh" by laymen, is an advanced form of chromatic aberration in a different dimension than lateral color. It can cause colored fringes on out-of-focus highlights, usually seen as green fringes on backgrounds and magenta fringes on foregrounds. Spherochromatism is common in fast lenses of moderate focal length when shooting contrasty items at full aperture. It goes away as stopped down."

Notice the background was green (past the point of focus) and the foreground was purple. High contrast subject made it worse. I have a Tele-Elmar coming on Thursday - so I am eager to test it. I have noticed CA with all of my lenses - although the 75 APO has the least as far as I can tell. I was assuming that the 135 APO would have less - but maybe it's a little over rated in that respect. Good to know that it is sharper than the Tele - Elmar...

Edited March 5, 2024 by Knightspirit

[lct]

Many (most?) good people here like technical explanations, i admire them for that, but i don't understand everything, if not anything, i must say. I prefer using simple words i comprehend myself like color fringing, with hope i can be understood by others. You cannot go wrong with the Tele-Elmar from this viewpoint. Couple of snaps with the M11 below.

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[adan]

1 hour ago, Knightspirit said:

I was assuming that the 135 APO would have less

Hmmm - why? See post #14, page 1 of this thread.

Getting the colors focused and sharp (repeat, focused and sharp) in the same plane is the only thing that defines an apochromatic lens. What happens in the unfocused and blurry parts of the image is not a factor in determining "apo performance."

........................

Not aimed anyone in particular.

But if one asked one of the 99% of optical engineers NOT working in the photo industry (and maybe even some who do), about "color bokeh" or "color effects in the out-of-focus areas," one would want to leave some space between one and them.

So they would have room to fall off their lab stools laughing hysterically. 😉

Blur is blur - a defect in the plane of focus, and completely irrelevant anywhere else.

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[Stuart Richardson]

Well, whatever it is, and however it is called, it is one of the ugliest optical effects a lens can have in my experience. We do not perceive the world as shifting towards magenta or green as we observe it with our eyes, so seeing it in a photo is somewhat jarring. The total lack of it in, the apo summicron SL lenses is one of the reasons why I like them so much. I had not realized that this was a characteristic of the 135mm APO, and that it was worse than the 135mm Tele Elmar (which I currently have). I found a decently priced copy today and was considering buying it, but this has given me pause...

Edited March 6, 2024 by Stuart Richardson