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  1. #31
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    Hi Guys

    The Hypergon is a very wide lens and if you like it soft it is almost like a softfocus lens. I have a print from a hypergon in a book from Andreas Feininger the famous photog. He also stated the Hypergon is not really very usefull it is very difficult to focus and gives not really sharp prints in comparison to todays lenses!
    But in some cases it was the only possibility at thad time!
    I not will stop your lens production but especially in the wide lens design was the most improvement.
    I can use a longer lens from in my case 1933 the 360 Universal Heliar and it gives me stopped down to 22-32 almost the same sharpness then a modern lens with the three-dimensional look wich I do not see in any modern lens!
    But if a take my 55 years old Super Angulon it has not any chance against a todays wideangel!
    Just some facts!

  2. #32
    Ole
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    I must admit I can't see that the sharpness of my 165mm Angulon is limiting in any way - I would be happy with that resolution on film in a 165mm lens for 35mm! I think some early super-angulons may well be less sharp than plain angulons of the same age?

    The real difference will be comparing a wide-angle Aplanat with an early Angulon. I'll try that next month.
    -- Ole Tjugen, Luddite Elitist
    Norway

  3. #33
    Donald Qualls's Avatar
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    Quote Originally Posted by phfitz
    I just wanted to polish out some cleaning marks from a 100 year old B&L Tessar. I will use a 2 part acrylic/urethane seam sealer instead of pitch and see how that works out. I don't like the idea of cooking up roof tar, it would smell like death.
    Based on my limited experience polishing an astronomical mirror, this is a very bad choice for polishing an optical surface. The process with pitch is to form the pitch to match the curvature of the glass surface by first hot pressing, and then cold pressing immediately before each polishing session. This ensures that you won't change the curve, or change it in (hopefully) predictable and controllable ways.

    Polishing long enough to remove cleaning marks may or may not change the lens prescription enough to matter, but doing it with a lap that doesn't precisely match the glass is guaranteed to destroy the lens rather than improve it.

    I agree with another poster -- rosin is a component of many optical pitch mixtures. Roofing tar is an expedient substitute and can work, but proper optical pitch is often genuinely pitch, as exuded by an evergreen tree, hardened by boiling, softened by adding turpentine, tempered by adding rosin -- and it's often a clear amber color rather than the black we're used to thinking of. Some optical pitches are made from asphalt, however, and road or roofing tar (actual petroleum based tars) can be tempered to make usable pitch.

    No two-part setting adhesive or sealer is going to produce a usable lap, because it can't be pressed to conform after it initially sets. Pitch must *flow*, both in use and in pressing, to do its job.
    Photography has always fascinated me -- as a child, simply for the magic of capturing an image onto glossy paper with a little box, but as an adult because of the unique juxtaposition of science and art -- the physics of optics, the mechanics of the camera, the chemistry of film and developer, alongside the art in seeing, composing, exposing, processing and printing.

  4. #34
    JohnArs's Avatar
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    Ole you always can have a keeper and be happy that you got one. My Super Angulon from the 50' is not a keeper at all. The sharpness is a curve in the picture and it is not really sharp against a today wide angle.
    Good luck!

  5. #35

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    Quote Originally Posted by JohnArs
    Ole you always can have a keeper and be happy that you got one. My Super Angulon from the 50' is not a keeper at all. The sharpness is a curve in the picture and it is not really sharp against a today wide angle.
    Good luck!
    If you are enlarging your negs this may indeed be an issue.

    If you are contact printing it should not be an issue.
    Tom Hoskinson
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    Everything is analog - even digital :D

  6. #36
    Ole
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    Quote Originally Posted by Tom Hoskinson
    If you are enlarging your negs this may indeed be an issue.

    If you are contact printing it should not be an issue.
    I've enlarged a 5x7" slide to 50x70cm, and there is no sign of unsharpness. Eirik Berger who did the scan for me reports slightly soft corners on 100x140cm, which I would say is big enough for me!
    -- Ole Tjugen, Luddite Elitist
    Norway

  7. #37
    Donald Qualls's Avatar
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    Yep, that's me from ATM. Built my telescope and then got away from it -- I wanted a big telescope, not to be a telescope builder, and building it let me spend the same $500 I could have used to buy a cardboard tube 8" Dobsonian, but do it over seven months and get a steel tube and a slightly better mirror with a wire spider (no visible diffraction spikes).

    But, as with a lot of other things I've done "just long enough" in the process I read enough to have a very good idea how the "deep" parts of the hobby would proceed...
    Photography has always fascinated me -- as a child, simply for the magic of capturing an image onto glossy paper with a little box, but as an adult because of the unique juxtaposition of science and art -- the physics of optics, the mechanics of the camera, the chemistry of film and developer, alongside the art in seeing, composing, exposing, processing and printing.

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