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Peter Wright

Does anyone expect a 35mm Summicron APO in the future?

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I have to wonder if we are likely to see a 35mm version of the 50mm Summicron APO that has had such good reviews.  As 35mm is almost a 'standard' Leica focal length, I would hope this would happen.

 

Any thoughts?

 

Peter.

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Yes.  The 35mm Cron Asph is an older design and doesn't perform up the standard of the newest Summicrons.  For a while Leica thought a 50 Apo was silly (Apo correction is typically associated with longer tele lenses), and that is why the 50mm Summilux Asph wasn't labeled as an Apo even though it is one.  Now that the 50 Apo-Summicron has been well received, I don't see why Leica wouldn't call a future 35mm Summicron an "apo".  

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It's coming at $9,000 in 2019.

 

 

Pure conjecture on my end.  

 

If you want something similar to an APO 35 cron go try the Zeiss 35 f/2.  It's that good, and I have the 35 ASPH.

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Hard to compare different focal lengths but the Summicron 35/2 asph has not more flaws than the Summicron 50/2 non apo and the latter is still alive since 1979 so the 35/2 asph has probably good days ahead it. Now there is some room for improvement, especially about CA, flare and distortion where a modest lens like the Biogon-C 35/2.8 does significantly better. An apo version of the 35/2 should be welcome then but a bulkier lens would not interest me personally.

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Always remember what "APO" means - correction so that three colors in the spectrum always focus in the same plane. APOchromatic, as opposed to chromatic (no color correction) or achromatic (2 colors corrected), or a SUPERachromat (4 wavelengths corrected). 

 

It corrects essentially a focusing issue in different wavelengths, which produces LONGITUDINAL chromatic aberration. One color is projected blurry while the other two are sharp. And the DOF of a 35 or wider lens is wide enough to prevent any noticeable LONG CA - it simply doesn't exist in the first place, at any scale that can be recorded. Whereas longer faster lenses (e.g. 75mm Summilux f/1.4, or 180 f/2.8, or 280/300 f/2.8) will reveal the problem very quickly.

 

https://cdn.photographylife.com/wp-content/uploads/2011/10/Longitudinal-Chromatic-Aberration.png

https://www.image-engineering.de/content/library/technotes/2011_08_12/longitudinal_chromatic_aberration_effects.jpg

 

Now, the current 35 ASPH may have LATERAL chromatic aberration - (opposed red/cyan or blue/yellow fringes, growing more extreme towards the corners), or other issues. Lateral CA is not a problem with focus, but with image size (the lens is producing a "larger picture" with blue light that with red, or vice versa, so that they do not align, and produce fringes). But that is a whole different problem to solve, and an APO lens can still produce lateral CA, and a non-APO lens may have well-corrected lateral CA (e.g. my 21 pre-ASPH Elmarit).

 

https://cdn.photographylife.com/wp-content/uploads/2011/10/Lateral-Chromatic-Aberration.png

https://cdn.photographylife.com/wp-content/uploads/2011/11/Uncorrected-and-Corrected-CA.jpg

 

And either may produce color fringes in OUT-OF-FOCUS areas - the APO designation is strictly about what happens in the focused area, not the blurry areas.

 

Leica can perhaps produce a better 35mm f/2 ASPH in the other ways lct mentions (distortion, flare, lat. CA) - but it won't be by correcting non-existent Long. CA to APO specs (since that would make no visible difference in a lens that already has no significant Long. CA).

 

Leica can, of course, stick the "APO" label on any lens it wants to, but in the case of 35mm lenses and wider, it would simply be a triumph of marketing make-believe over engineering reality.

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[...] It corrects essentially a focusing issue in different wavelengths, which produces LONGITUDINAL chromatic aberration. One color is projected blurry while the other two are sharp. And the DOF of a 35 or wider lens is wide enough to prevent any noticeable LONG CA - it simply doesn't exist in the first place, at any scale that can be recorded. Whereas longer faster lenses (e.g. 75mm Summilux f/1.4, or 180 f/2.8, or 280/300 f/2.8) will reveal the problem very quickly. [...]

 

Interesting thanks. Would you say the Summicron 50/2 non apo had enough long CA to justify an apo correction? Just curious.

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I don't use any 50 enough to judge that. I wasn't especially aware of long. CA on the few times I used the current 50 non-APO (but that was in the M8 era) - but certainly not as much as in some other lenses of the same age/era (90 Summicron, 75 Summilux, 180 R non-APOs).

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Hello to D.Os. (Doctor in Optic)

 ,

 

In order to restart this topic on a lateral way, may I ask : "does anyone expect a 35mm noctilux in the future?" ... in silver for me .

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Just for the record: obviously there already is a "Notcilux 35" around, except its from Cosina/Voigtländer; the Nokton 35mm f1.2.

 

Honestly I dont know if its a good idea to try to make a 35mm APO in the first place, but we'll see.

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And there is no prize for guessing that the next fast lens from Leica will be a Noctilux 35....

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Always remember what "APO" means - correction so that three colors in the spectrum always focus in the same plane. APOchromatic, as opposed to chromatic (no color correction) or achromatic (2 colors corrected), or a SUPERachromat (4 wavelengths corrected). 

 

It corrects essentially a focusing issue in different wavelengths, which produces LONGITUDINAL chromatic aberration. One color is projected blurry while the other two are sharp. And the DOF of a 35 or wider lens is wide enough to prevent any noticeable LONG CA - it simply doesn't exist in the first place, at any scale that can be recorded. Whereas longer faster lenses (e.g. 75mm Summilux f/1.4, or 180 f/2.8, or 280/300 f/2.8) will reveal the problem very quickly.

 

https://cdn.photographylife.com/wp-content/uploads/2011/10/Longitudinal-Chromatic-Aberration.png

https://www.image-engineering.de/content/library/technotes/2011_08_12/longitudinal_chromatic_aberration_effects.jpg

 

Now, the current 35 ASPH may have LATERAL chromatic aberration - (opposed red/cyan or blue/yellow fringes, growing more extreme towards the corners), or other issues. Lateral CA is not a problem with focus, but with image size (the lens is producing a "larger picture" with blue light that with red, or vice versa, so that they do not align, and produce fringes). But that is a whole different problem to solve, and an APO lens can still produce lateral CA, and a non-APO lens may have well-corrected lateral CA (e.g. my 21 pre-ASPH Elmarit).

 

https://cdn.photographylife.com/wp-content/uploads/2011/10/Lateral-Chromatic-Aberration.png

https://cdn.photographylife.com/wp-content/uploads/2011/11/Uncorrected-and-Corrected-CA.jpg

 

And either may produce color fringes in OUT-OF-FOCUS areas - the APO designation is strictly about what happens in the focused area, not the blurry areas.

 

Leica can perhaps produce a better 35mm f/2 ASPH in the other ways lct mentions (distortion, flare, lat. CA) - but it won't be by correcting non-existent Long. CA to APO specs (since that would make no visible difference in a lens that already has no significant Long. CA).

 

Leica can, of course, stick the "APO" label on any lens it wants to, but in the case of 35mm lenses and wider, it would simply be a triumph of marketing make-believe over engineering reality.

 

Andy,

 

Longitudinal and lateral chromatic aberration are actually one and the same phenomenon.  Longitudinal chromatic aberration is seen on axis while lateral chromatic aberration is seen in the field.  This is well illustrated in the first and third web references you give.  And thanks for posting the web references.

 

Guy

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Andy,

 

Longitudinal and lateral chromatic aberration are actually one and the same phenomenon.  Longitudinal chromatic aberration is seen on axis while lateral chromatic aberration is seen in the field.  This is well illustrated in the first and third web references you give.  And thanks for posting the web references.

 

Guy

 

Only at the gross level, in that they both stem from glass lenses' dispersing wavelengths of light differently (cf. Newtonian prism).

 

Long CA is a focus error - the three colors hit the same place on the image plane, but focused in different planes.

 

Lat CA is a magnification error - the three colors hit different places on the image plane, but focused in the same plane.

 

If they were truly "the same phenomenon" it would not require two different algorithms to correct them digitally - scaling one or more color channels to correct Lat CA, and "desaturation" of specific purples, greens, or other colors to eliminate long CA fringes.

 

Nor, of course, would the optical industry still have separate names for them.

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