Schneider-itis: The Perennial Problem

[Bernice Loui]

Trying to compare the slightly degraded edge coating 210mm SSXL to another lens of similar focal length is NOT a valid comparison for a very long list of factors, from different lens formula/design, focal length, lighting conditions and how this impacts the film image, reflectance from film, variations in lens coatings, stray light inside the bellows caused by over sized image circle and much more.

~The Only Valid comparison test is absolute identical image making conditions with the lens "perfect" then under absolutely identical conditions with the same lens edge coating degraded.~

As for the flocked -vs- non flocked as delivered projector lens example, this is typical of a lower quality projector lens. Projection lenses same as other optics comes in a variety of abilities and designs goals. Consider the Schneider Cinelux


or ISCO Ultra Star projection lenses


The stray light causing contrast reduction is very similar to stray light inside the camera bellows from a lens with far excessive image circle for the needs of the film image area.

Attraction of these projection lenses is much about their large aperture, out of focus rendition and into out of focus rendition, which has become a 'thing" of fashion these days with sheet film. This image style trend appears to be a carry over from 35mm and digital image styles where large full aperture lenses are often used in this image making style. Yet, this image making style has been around long ago, common in cinema folks and sheet film folks from decades ago. Then came the group f64 "everything in the image must be in sharp focus" image style.. which pushed out the how out of focus and into out of focus rendition image making style. This appears to be why the absurd market value for large full aperture sheet film lenses like the Schneider 150mm f2.8 Xenotar and others.

This brings up the topic of barrel lenses and older shutters with a nice round iris -vs- modern shutters like Copal/Compur/Prontor/ Sinar DB/DBM mount and others with less than round iris due to the lesser need to be concerned with out of focus and into out of focus rendition due to the influence of Group f64 on sheet film images. Projector lenses tend to have no iris and large apertures with an image circle that can be large enough for various film or digital imager format.




Bernice

I'll do what I can before sending the lens off next month.
It would be difficult to get the exact same conditions, but I'll make notes.

Here's a different lens with a slightly different issue, but worth noting.
This is a projector lens I have. The inside was not black, it was more of a dull dark gray.
I blackened the inside, and the differences are immediately apparent.
I'm starting to see the same effect on the 210, though it's very minor compared to the projector lens problem shown below.

[Daniel Unkefer]

Interior lens flare is measurable with the Sinarsix TTL. Depending on lighting conditions a good compendium can make a measurable difference. I'm not saying it is in this case, but it is a possibility even with multicoated lenses. Your flocked projection lens photo is lovely, I like it. I have an old magic lantern brass lens that draws kind of like that.

[Ari]

Thanks, Daniel!

[Kevin Crisp]

On the protars I have disassembled and reglued, the black (glossy, by the way) edge paint naturally comes off during the MEK or Acetone soaking to clean off the balsam. It may sound dumb, but I've reapplied the black around the finished lens with a sharpie. After a second coat, it is quite black and has always worked fine for me.

[Ari]

On the protars I have disassembled and reglued, the black (glossy, by the way) edge paint naturally comes off during the MEK or Acetone soaking to clean off the balsam. It may sound dumb, but I've reapplied the black around the finished lens with a sharpie. After a second coat, it is quite black and has always worked fine for me.

Dollar General magic marker is good, but I would not use it on this lens because it's not a common lens and it stains the glass. It won’t come off even with acetone.

[Nodda Duma]

On the protars I have disassembled and reglued, the black (glossy, by the way) edge paint naturally comes off during the MEK or Acetone soaking to clean off the balsam. It may sound dumb, but I've reapplied the black around the finished lens with a sharpie. After a second coat, it is quite black and has always worked fine for me.

We use sharpie at work when needed. Fun fact: Black sharpie is approved for edge blackening for space applications.

[Nodda Duma]

Yes, I'm interested on your opinion of the lack of edge blackening on the lens elements only visible when the lens is disassembled? But it does look like he found someone to repaint it so you don't have to answer if there is no good answer.

Assuming the lens designer is competent, the edges selected are based on
1) stray light analysis to determine which edges cause artifacts
2) balance contrast (sometimes too much isn’t wanted
3) since consumer optics treat low manufacturing cost as a top priority, only the bare necessity.

Nothing magical about it… just engineering to meet the design requirements

-Jason

[Alan Klein]

I have a Schneider Kreuznach 150mm Apo Symmar F5.6 MC Lens without schneideritis. I bought it 2 years ago when I started 4x5 photography. Can I expect it to get "sick"?

[Mark Sampson]

No, but you can make yourself sick with worry about it. It's a popular pastime among Schneider lens owners.

[Bernice Loui]

Not just Schneider can be infected, there is Rodenstock-itis, Fujinon-itis and many others can be infected by the same -itis..

Having been round enough lenses with -itis, this kind of infection is not worth getting worked up about. If there is a nano amount of contrast degradation and this nano amount of contrast degradation "makes or bust" your image, gotta wonder.


Bernice

I have a Schneider Kreuznach 150mm Apo Symmar F5.6 MC Lens without schneideritis. I bought it 2 years ago when I started 4x5 photography. Can I expect it to get "sick"?