Lens corrections, or lack thereof, for the Leica m 35 apo

[M Journey]

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I clicked on the lens corrections for a photo in lightroom for the Leica m35 apo and was surprised to see how little there was (all I could see was that the photo zoomed in slightly with corrections turned on).  For those that are interested, the first image is without any lens corrections and the second photo had both "Remove Chromatic Aberration" and "Enable Lens Correction" turned on.  No other edits have been applied besides Lightroom using their default m11 profile.

You can download the original raw file here:  https://drive.google.com/drive/folders/1n0R_vs-m7AhqUH0Gt-Z1Xp4T1-b0KFu7?usp=sharing

Shot with m11, ISO 64.

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Edited March 7, 2022 by M Journey

[adan]

Yep - the APO-Summicron 35 has optical corrections that, while a little distorted (1% barrel) part way to the corners, are pretty much already corrected back to the corners by the time the light leaves the lens. (What I call "handlebar moustache" distortion, and something Leica has been doing to one extent or another all the way back to the 21mm Elmarit of 1980 (not always as well as in the 35 APO, though )).

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Not much left for a profile to fix, unless you shoot a brick wall, and then carefully watch the straight edges away from the corners while turning corrections on and off (e.g. about where the bright tree trunk is reflected in the pond on the left center).

By definition, if it is "APO," it will have only minor CA as well (if any at all).

And since it is 6-bit coded, the camera will have taken care of any color drift on the edges ("Italian Flag") as well as overall vignetting.

Edited March 7, 2022 by adan

[M Journey]

9 minutes ago, adan said:

Yep - the APO-Summicron 35 has optical corrections that, while a little distorted (1% barrel) part way to the corners, are pretty much already corrected back to the corners by the time the light leaves the lens. (What I call "handlebar moustache" distortion, and something Leica has been doing to one extent or another all the way back to the 21mm Elmarit of 1980 (not always as well as in the 35 APO, though )).

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Not much left for a profile to fix, unless you shoot a brick wall, and then carefully watch the straight edges away from the corners while turning corrections on and off (e.g. about where the bright tree trunk is reflected in the pond on the left center).

By definition, if it is "APO," it will have only minor CA as well (if any at all).

And since it is 6-bit coded, the camera will have taken care of any color drift on the edges ("Italian Flag") as well as overall vignetting.

Do you mean that the camera is performing some corrections on the image that can't be turned-off by Lightroom?  I've heard that this is the case for Nikon z files, where you can't turn off some of the corrections (I think you can on capture one though).

Lens corrections is supposed to warp the quality in the corners right?   I wonder if its just better to always toggle off lens corrections for this lens to get the best quality from the corners.

[anickpick]

I think, it's a bug: Lens corrections do not work in Lightroom for the M11.

Not a big deal when using the 35 Apo. The WATE on the other hand is pretty much useless for anything that has straight lines. 

[adan]

5 minutes ago, M Journey said:

Do you mean that the camera is performing some corrections on the image that can't be turned-off by Lightroom?

Absolutely - every M digital from the beginning has had baked-in corrections for color stains and "abnormal vignetting" due to historic incompatabilities between old-school compact RF lenses and the (microscopic) 3D structure of digital sensors. It is the primary technical reason for 6-bit lens coding. And why Leica originally said for 4 years that "a digital M was impossible."

See samples below.

Unless you really want to see candy-colored edges like these in your pictures, there is no purpose to "turning it off."

And it has to be done in-camera for .jpg images anyway. So Leica's firmware neutralizes the colors around the edge on the fly, according to the "known pattern" each individual lens design (mostly wide-angles) will produce.

Less so, probably, with the M11's "flatter" BSI sensor. But likely still needs some firmware help for consistent color, edge to edge, with wider lenses "of a certain age."

Leica does not correct in-camera for distortion or CA - they simply design their M lenses, as much as possible, with no distortion or CA in the first place (as I said, optical corrections, i.e. done with the glass, not the camera - that is what you are paying the $8000 for). And then provide a profile for additional corrections in LR, etc., if desired or needed.

(Leica 21mm Elmarit-M (1983 lens) on M9, with early and faulty correction for color vignetting (a.k.a "Italian Flag syndrome" - the pink and cyan snow) for this particular lens - fixed in a later firmware version)

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(Green and blue vignetting on a beige pavement (M9, uncoded 35mm f/1.4 pre-ASPH lens))

[Jon Warwick]

1 hour ago, adan said:

Absolutely - every M digital from the beginning has had baked-in corrections for color stains and "abnormal vignetting" due to historic incompatabilities between old-school compact RF lenses and the (microscopic) 3D structure of digital sensors. It is the primary technical reason for 6-bit lens coding. And why Leica originally said for 4 years that "a digital M was impossible."

 

 

So I've found lenses like the Voigtlander 50mm APO Lanthar are incredibly good, but clearly not 6-bit coded ....and from your comment, it sounds like there is a need for baked-in corrections for color stains & vignetting. What should one do for these 3rd party lenses, manually put into the camera the nearest Leica lens equivalent (which, for a VM 50 APO Lanthar is presumably the M 50 APO Summicron ......for the VM 35mm APO Lanthar, the M 35mm APO Summicron)? Many thanks.

[adan]

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50mm lenses are on the borderline - some may show a bit of color vignetting or grayscale vignetting; others may not.

It depends on the exact optical formula, and how close the exit pupil of the lens is to the sensor - the exit pupil is the point in the lens from which the light rays splay out sideways, to project onto the entire 24mm x 36mm image area.

It is possible to hand-code lenses (either old Leica lenses or 3rd-party lenses) by adding the correct pattern of black dots/marks to the lens flange, with paint or even fine-tip permanent marker (Sharpie™).

Usually that will tend to wear off quickly from the friction of mounting and unmounting the lens (Leica's own painted spots are in recessed pits in the metal, to protect them from that). Since 2010 or so (?), Cosina has machined a concentric trench in the flanges of Voigtländer lenses (and the lenses they make for Zeiss ZM) - which also allows putting the black marks below the bearing surface of the lens mount, and protect them from wear.

Or - yes - one can use the lens menu to choose a Leica lens that - with luck - has an optical formula "close enough" to a third-party M lens to work. (Just keep in mind that since it is the exact optical formula and light paths that matter, one cannot assume that "all 35mm f/2 APO lenses are identical."

As to which 3rd-party lenses and Leica lenses are reasonably equivalent (whether hand-coded, or selected from the menu), here is one not-entirely-up-to-date "list."

https://lavidaleica.com/content/leica-lens-codes

Here is a snap of my own hand-coded 35mm f/1.4 Voigtländer Nokton, showing the marking and the shallow protective "trench" Cosina cuts in the metal for just that purpose. Two years so far with no significant rub-off. The coding is for a "35mm Summicron v.4," since that is a similar compact double-gauss optical formula to the Nokton f/1.4

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