Jonas B
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 p.119 #3 · which lens has the most 3D POP? | |
RustyBug wrote:
Unfortunately, I came to this pseudo-perspective more than a decade ago. The unfortunate part is that when I was studying this for my personal understanding, I did not save all the documentation that I found for such things.
For instance, there was a "great shootout" for (28mm or 24mm) that pitted a large fielding of lenses. In the course of the shootout (not mine) there was significant discussion about how to value the transitions through Zones A/B/C ... and credence given to the evenness across the frame for doing so.
Meanwhile, there were articles regarding Leica ethos for specifically designing transition zones for the purpose of "layering" the scene.
Sadly, despite having looked numerous time to find theses sources again, I have not been able to re-locate them. This story repeats itself in a variety of aspects, where I onboarded the information, but didn't retain the source info for posterity.
My studies of the matter were ongoing with my art school work. Had I known there would "be a test" decades later, I might have kept better files. Should I happen to find them ... I'll certainly share with our fellow members.
Although ... I have shared certain aspects of this with direct links to Leica / Karbe / etc. ... and some folks persist to totally dismiss the legitimacy of that source information, so it can be questionable whether or not people actually are trying to understand ... or, are they just desiring to dismiss my position. But, I'll still share because even though there are absolutely ardent folks who take up their position in vocal opposition to mine ... there remain fellow members who "lurk" ... and if my offerings aid them, then I'm good with that, too. 
Again, sorry I don't have that source info ... wish I did.
As to intentional design choices ... Mandler vs. Karbe. 
For optical designers, it's always by intent (even where quid pro quo reigns).
The question is what the intent is ... generic, well corrected, as even across the zones as possible. Or, harness the differences.
As I mentioned before about my 28's (of yore in the EF mount adapted lens heyday), my Oly was most even across the zones A/B/C, my Nikon AIS was most Zone A centric, and my C/Y was somewhere between both of them. Depending on what I was shooting for, I'd grab a different lens, per its zone transitions.
As a brain tickler ... when / why would a lens designer choose to have forward field curvature vs. rearward curvature vs. flat?
How would those choices influence or differentiate (or not) depth perception. How would that be if the subject was bright and the BG dark, with forward curvature vs. rearward curvature. What if the subject / BG tonal values are reversed ... would forward or rearward curvature amplify or offset depth or projection perceptions? What influence would vignetting have? What influence would reduction in contrast / detail have in a given zone?...Show more →
I suppose there might be some benefit to a lens where the focal plane tilts forward or backward when taking photos without being positioned directly in front of a reasonably flat surface.
For me, that’s a problem because I don’t carry more than one prime lens in every focal length. It would also be a bit of a hassle to remember all the details. I’m taking the other approach, keeping things a bit simpler, and I want lenses that can take a reasonably sharp image of a flat surface, from the left to the right side of the frame.
In other words, for example, there’s no ZM 35/1.4 for me; I strongly dislike focus planes that curve backward. The images look unnatural to me if the background in the center is slightly blurry while it gets sharper toward the edges. Yikes.
I had a nice Summilux 35/1.4 ASPH pre-FLE. Some images were wonderfully beautiful. Others, unfortunately, weren’t critically sharp across the width of the image. This last point was very annoying. A mid-zone dip to be sure.
Perhaps this dip was intentional on the part of the lens designer. I’ve never thought of it that way before, but the result was that I sold the lens after a while anyway.
If you look at the MTF charts for the current Summilux-M 35/1.4 Classic and Summilux-M 35/1.4 ASPH FLE, you can see that both have a mid-zone dip, but that it is significantly less pronounced now than before. You can also see that there is a very large difference in sagittal and tangential “structures.”
I’m still pretty skeptical that this was intentional. Maybe it was, but they just failed a bit at keeping sag and tan in sync.
Oh, btw, one new modern lens I’m passing on due to concerns about similar issues (among other problems) is Voigtländer’s new 40mm Septon.
Oh well. Not much new here. But it’s always interesting to discuss lens design without hyperbole. Regards!
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