So why the big deal with corner-to-corner focus and uniformity?
You misunderstand the position. You need to distinguish picture content from channel content.
Picture content is the program material... the decision of the film-makers.
Channel content is associated with the resolution of the projector.
You should always strive to present picture content in the best possible way, by maximising the presentation of the channel content. Hence, edge-to-edge sharpness is important to the process, as is the least amount of distortion that you can achieve in an affordable way. However a scene is focused in the camera - sharp or blurred in the background - the tiling of the projector pixels should be visibly as sharp as possible, edge-to-edge to best present that content.
Think of it this way: you can play a perfectly recorded and manufactured CD on a crappy boom box, or on a $10,000 (or more) sound system. It will sound different between the two media (or channels). If what you want is the best quality sound you can afford, you tend to purchase towards the hi-fi system, not the boom box.
Wolfgang based his criticism on a test pattern that comprised 1-pixel squares or lines extrapolated in size (vertically) 1.33 to one to fill the screen height. There's no way known that ANY software extrapolation can perfectly preserve a 1-pixel pattern in anything but even multiples (2x, 4x etc.).
Wolfgang's unstated assumption was that Blu-Ray movie
material comprised 1-pixel wide detail, which for vastly the main part, it does not. Even a single human hair blowin' in the wind in a movie will occupy several pixels of bandwidth and soften off towards the edges, whether you have a lens-in or lens-out situation. He took a false assumption and then applied it to a meaningless situation.
If we used projectors and anamorphic lenses (for some reason) to look at 1-pixel-mapped PC data displays, he'd have a point, because PC displays are somewhat analogous to test patterns (with 1-pixel wide or high lines being common in these displays). But we don't... we look at continuously toned movies that don't have the resolution of PC data displays. Hence, vertical stretch is perfectly fine and acceptable for watching motion content with anamorphic lenses.
are you sure about that or is it just a theory. besides isnt the anti-reflective coating applied to the element where the light exits and is facing the projector? so if reversed that side would face the projector and become the entry point of the lens. will the AR coating affect the entering light beam? also the element now facing the projector will have no AR coating. what are the effects of the above situation. also what happens to the focus and astigmatism adjustmen rings usage? basically what modifications would be required if any to the HE lens to use it as a VC lens and could anyone do it for me.
AR coating is applied to BOTH sides of lenses. Light exiting
a lens can be reflected at the air-glass interface, just as light entering
a lens can.
The reason you can't practically
reverse a purpose-built HE anamorphic lens and make it a VC lens is because, although the optics might work (not too well, actually, because the lens is not optimized for this), the lens sizes are exactly reversed from what they should be. The entry lens should be the small one. The exit lens the big one. Reversing a lens makes sure this situation doesn't arise. You'd have severe vignetting in this case, if you reversed a typical HE lens. It'd be like looking through a keyhole, with only the centre of the image showing up on the screen, except in the rarest of cases where the TR is quite large.
A better "quirky" application of changing the positioning of an HE lens is to rotate it 90 degrees and watch "classic" 1.37 ratio movies with it. First, instead of expanding the image vertically
you expand the image horizontally
so that the ~1.37 ratio becomes ~16:9. Then, with the lens rotated 90 degrees, you optically
expand by 1.33, restoring image geometry.
The final result is a 1.37 movie projected using all 1920 x 1080 pixels. Because you have to zoom in a bit to fit image height, the picture will be a lot brighter (concentrating more light into a smaller area).
Note: you need a lens that can rotate 90 degrees in its holder to do this.