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Thread: optics question

  1. #21
    Drew Wiley
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    Re: optics question

    Here we go again. People inferring that it was good enough for Ansel, it's good enough for us. But have you ever seen those particular images enlarged more than 3X ? The aspen shot seems to hold up; but the others lose definition.

  2. #22
    (Shrek)
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    Re: optics question

    Quote Originally Posted by Bob Salomon View Post
    Zoom lens or varifocal lens?
    Varifocal, of course. There were no zoom lenses in the 1910s or 20s.

  3. #23

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    Re: optics question

    Quote Originally Posted by Jody_S View Post
    Varifocal, of course. There were no zoom lenses in the 1910s or 20s.
    From Wikipedia:

    “The first true zoom lens, which retained near-sharp focus while the effective focal length of the lens assembly was changed, was patented in 1902 by Clile C. Allen (U.S. Patent 696,788). An early use of the zoom lens in cinema can be seen in the opening shot of the movie "It" starring Clara Bow, from 1927.”

  4. #24

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    Re: optics question

    Quote Originally Posted by Bob Salomon View Post
    From Wikipedia:

    “The first true zoom lens, which retained near-sharp focus while the effective focal length of the lens assembly was changed, was patented in 1902 by Clile C. Allen (U.S. Patent 696,788). An early use of the zoom lens in cinema can be seen in the opening shot of the movie "It" starring Clara Bow, from 1927.”
    Quote Originally Posted by Jody_S View Post
    Varifocal, of course. There were no zoom lenses in the 1910s or 20s.

    Here we distinguish "zoom lenses" from "true (parfocal) zoom lenses". IMHO the concept is fuzzy. Perhaps "true zoom" is more related to cinematography, but "zoom" is a more generic term in still photography, I'd say.

    I fact the same wiki article you cite soon starts naming zooms to any variable focal length lens...

    Anyway today parfocal design is obsolete in DSLRs, as varifocal is technically better and the electronics mantains focus while zooming with varifocal lenses (as the case of Nikon 70-200 f/2.8), having great advantages (weight, size, cost).

  5. #25

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    Re: optics question

    Quote Originally Posted by Drew Wiley View Post
    Here we go again. People inferring that it was good enough for Ansel, it's good enough for us. But have you ever seen those particular images enlarged more than 3X ? The aspen shot seems to hold up; but the others lose definition.
    Drew, do you think that were AA lenses performing under 25 lp/mm ? Not at all!

    If one can obtain 50 lp/mm in 4x5 (IMHO a difficult challenge for most situations) this would be worse IQ than 8x10 at 25 lp/mm, mainly because film is degradating IQ at 50lp/mm in common low micro contrast.

    If having 25 lp/mm an x5 enlargement still would show 5 lp/mm on paper, so no flaw would be seen with the viewer's nose on a 1,2m print.

    What I say is if not all AA photographs were completely sharp it could be because other reasons, like DOF, focusing, wind or enlargement.

  6. #26

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    Re: optics question

    Quote Originally Posted by Pere Casals View Post
    Bob, here we distinguish "zoom lenses" from "true (parfocal) zoom lenses". IMHO the concept is fuzzy. Perhaps "true zoom" is more related to cinematography, but "zoom" is a more generic term in still photography, I'd say.

    I fact the same wiki article you cite soon starts naming zooms to any variable focal length lens...

    Anyway today parfocal design is obsolete in DSLRs, as varifocal is technically better and the electronics mantains focus while zooming with varifocal lenses (as the case of Nikon 70-200 f/2.8), having great advantages (weight, size, cost).
    No question about the terminology. But zoom lenses are o
    Dear then the poster stated.
    BTW, I sold the Voightlander Vario 36 to 82mm for the Bessamatic when it was originally introduced in 1959. Interesting lens but heavy!

  7. #27

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    Re: optics question

    Quote Originally Posted by Bob Salomon View Post
    No question about the terminology. But zoom lenses are o
    Dear then the poster stated.
    BTW, I sold the Voightlander Vario 36 to 82mm for the Bessamatic when it was originally introduced in 1959. Interesting lens but heavy!
    Bob, you really sold entire ships of glass, I think I can calculate it, just taking the serial numbers in the active years and guessing the production share that was going to your markets... this is a large amount of glass... that glass amount is not a joke...

  8. #28

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    Re: optics question

    Quote Originally Posted by Pere Casals View Post
    Bob, you really sold entire ships of glass, I think I can calculate it, just taking the serial numbers in the active years and guessing the production share that was going to your markets... this is a large amount of glass... that glass amount is not a joke...
    I wish I had. But my background in photo sales started in a very well equipped regional retailer in 1957 and ended as a well known USA importer and distributor that heavily specialized in European and, especially, German photo products. Along the way I also worked for the 8mporter and distributor of Sinar and Nikon at the time that Nikon introduced their LF lenses. So I represented Nikon, Rodenstock and Schneider lenses during that time.

  9. #29

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    Re: optics question

    Quote Originally Posted by Nodda Duma View Post

    A large format continuous zoom would be fun to design. It wouldn't be as big as one would think.

    A 90mm to 210 or 240mm zoom would be nice for the 4x5 shooters. I'd be afraid to ask what it would cost though!

  10. #30

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    Re: optics question

    Quote Originally Posted by Alan Gales View Post
    A 90mm to 210 or 240mm zoom would be nice for the 4x5 shooters. I'd be afraid to ask what it would cost though!
    IMHO in LF a zoom is less needed because you always can crop and still having IQ in excess, smaller formats have severe IQ problems when making a crop...

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