Jim Roof
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 p.7 #19 · 2 new lenses, 17 and 24mm TSE | |
jjlphoto wrote:
Jim Roof wrote:
.....since most 35mm WA lenses were not designed to the same exacting standards as LF lenses. BTW, MF lenses barrel distort too....
Jim- actually the opposite is the case. Since 4x5 get enlarged very little compared to a 35mm size, 4x5 lenses didn't need to be that good at all. The barrel distortion is because lenses for reflex cameras (cameras with mirrors and pentaprisms) are of the "retro-focus" design school. That means they are planted further away from the film plane than a rangefinder or large format lens is designed to sit (in order to clear the mirror.)
The Hasselblad 38mm Biogon was a symmetrical lens design, and hence was sold permanently mounted on a very thin Hasselblad body that did not have a mirror (or focus screen on top). It had very little noticeable linear distortion (barreling) as a result. Compare that to its closest cousin that gets used on a conventional 500 series Hasselblad body, the Hasselblad 40mm Distagon, and that lens shows lots of barreling. Same thing when you compare the Zeiss 21mm Biogon for the M-mount rangefider (very little linear distortion) against the Zeiss 21mm Distagon for the SLR (more barreling again).
I am not a lens designer so I may be off on the history of lens design for various formats, but I have used a lot of LF lenses (I used to own ten different focal lengths for my work). Suffice it to say that this might be a cart and horse, or perhaps horse and cart issue as my point was that 35mm lenses did indeed exhibit barrel distortion almost without exception whereas LF lenses did not, almost without exception. In fact, I know of no view lenses that were not straight as arrows though my Nikkor f/4 65 would LOOK like it distorted at times because the film holders could not keep film perfectly flat all the time.
As for MF, I shot a Pentax 6x7 and as I recall my 45mm Takumar was not that bad but it was not as straight as the view lenses.
My point was this, 35mm wides almost always have barrel distortion. Prior to any digital manipulation in the work flow they were almost useless for shooting serious architecture. For this reason 4x5 was the camera of choice. It also gave nice sharp and detailed images that were relatively grain-free. Sure, the lenses were of a simpler design (you brought this out) but this in no way negates my claim that they were made to exacting standards. No doubt a decent 35mm lens, say at a 75mm focal length, would out-resolve a 75mm Super Angulon per square mm on the film, but the 75mm 35mm optic is not going to have an angle of coverage that almost covers a 5x7. From the standpoint of precision, whether it is the result of 'exacting standards' or not, the LF wides out-performed anything when it came to distortion. BTW, I have bought enough them also to realize that, absent AF motors, circuit boards, and internal focusing mechanics, the price would lead one to believe that they were precision instruments as well.
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. Diminishing view aside, the lens distortion is what I was trying to hit on. I guess it's more an issue of people getting it correct in camera vs. relying of photoshop to fix it in post.
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