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Thread: 20x24 lenses

  1. #21
    Mark Sawyer's Avatar
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    20x24 lenses

    Ole- Apo-Tessars out, regular and Aero, maybe... Thank you!

    John- Thanks, you just saved me $150; I was thinking of ordering the 530mm Ektanon.

    Dan- Yes, I've heard the Aero Tessars/Ektars were made for 9x9 and 9x18, but then the Nikkor-M 450mm is for 8x10 with a rated coverage of 440mm. I may end up springing for the Nikkor or Fujinon, but I'll grumble about it for years...
    "I love my Verito lens, but I always have to sharpen everything in Photoshop..."

  2. #22
    Greg Davis's Avatar
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    Re: 20x24 lenses

    An older thread, but I just got a 21 inch Eastman Anastigmat f/10 lens and measured the image circle at 32 inches diameter. It covers 20x24, but the corners would be fuzzy if movements were applied. Closer subjects would be perfectly fine. Coverage did not improve stopped down, but corner sharpness seemed to a little.

  3. #23
    Lachlan 717
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    Re: 20x24 lenses

    Quote Originally Posted by Greg Davis View Post
    An older thread, but I just got a 21 inch Eastman Anastigmat f/10 lens and measured the image circle at 32 inches diameter. It covers 20x24, but the corners would be fuzzy if movements were applied. Closer subjects would be perfectly fine. Coverage did not improve stopped down, but corner sharpness seemed to a little.
    Does your copy have the reversed lettering inside the barrel ring?

    I had no idea that their coverage was so significant!
    Lachlan.

    You miss 100% of the shots you never take. -- Wayne Gretzky

  4. #24
    Mark Sawyer's Avatar
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    Re: 20x24 lenses

    Quote Originally Posted by Mark Sawyer View Post
    Okay, it wasn't exactly what I set out to do, but it happened. I bought a 300mm Astragon in a very nice Copal 3 for my 8x10 for $150. Not too bad, right? Here's the problem- it came with a partially finished 20x24 camera...

    To make it all work, I'd need to build a back, a bed, and a couple of filmholders. It's a lot of work, but I can do that. But what to do for a lens?...
    Sort of an update, a friend has that bellows now. But I ended up with a 16-inch Globe lens, so I'm building a whole new mammoth plate camera around it. And in the middle of building it, I fell into a 1-meter Voigtlander/Petzval Orthoscop. And I have a few others that will cover. Still gotta make a wet plate silver tank...

    Oh, what 14 years will do...
    Attached Thumbnails Attached Thumbnails c34s.jpg  
    "I love my Verito lens, but I always have to sharpen everything in Photoshop..."

  5. #25

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    Re: 20x24 lenses

    Quote Originally Posted by Greg Davis View Post
    the image circle at 32 inches diameter. It covers 20x24, but the corners would be fuzzy if movements were applied.
    Quote Originally Posted by Lachlan 717 View Post
    I had no idea that their coverage was so significant!
    IMHO the "image circle" term is a bit ambiguous, we have the illumination "image circle" and the good quality "image circle". I'd say that in LF "image circle" is often used to say the good quality "image circle", or coverage.

    "Coverage" usually improves when stopping a LF lens, this is the good quality "image circle" grows.

    In "simple" lenses there is a big difference, I've just tested my Symmar converted to 620mm and the half plasmat illuminated beyond 70, while manufacturer stated a 45 coverage. Not a surprise that the illumination is beyond 70, because the front half lens has to catch at least those 70 to be deliverered to the rear half lens, which also sees 70...

  6. #26
    Lachlan 717
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    Re: 20x24 lenses

    Quote Originally Posted by Pere Casals View Post
    IMHO the "image circle" term is a bit ambiguous, we have the illumination "image circle" and the good quality "image circle". I'd say that in LF "image circle" is often used to say the good quality "image circle", or coverage.

    "Coverage" usually improves when stopping a LF lens, this is the good quality "image circle" grows.

    In "simple" lenses there is a big difference, I've just tested my Symmar converted to 620mm and the half plasmat illuminated beyond 70, while manufacturer stated a 45 coverage. Not a surprise that the illumination is beyond 70, because the front half lens has to catch at least those 70 to be deliverered to the rear half lens, which also sees 70...
    Mansplaining to men. Interesting development of the concept.
    Lachlan.

    You miss 100% of the shots you never take. -- Wayne Gretzky

  7. #27

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    Re: 20x24 lenses

    Quote Originally Posted by Lachlan 717 View Post
    the concept.
    Those concepts had (and have) some controversy... Following some wrong commercial translations from German some people started mixing angle of view and coverage, etc... The right concepts and definitions are in The Camera, Ansel Adams was pretty clear.

    In this list https://www.largeformatphotography.i...s/LF4x5in.html "Image Circle" is used as the good quality "Image Circle", or nominal Coverage, I think this is the best convention for LF, but I'd say that in smaller formats "Image Circle" it's often referred as the illumination circle, adding controversy. In small formats movements are not frequent at all, so no problem if what it is said it's not clear.

  8. #28
    Greg Davis's Avatar
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    Re: 20x24 lenses

    Quote Originally Posted by Pere Casals View Post
    IMHO the "image circle" term is a bit ambiguous, we have the illumination "image circle" and the good quality "image circle". I'd say that in LF "image circle" is often used to say the good quality "image circle", or coverage.

    "Coverage" usually improves when stopping a LF lens, this is the good quality "image circle" grows.

    In "simple" lenses there is a big difference, I've just tested my Symmar converted to 620mm and the half plasmat illuminated beyond 70, while manufacturer stated a 45 coverage. Not a surprise that the illumination is beyond 70, because the front half lens has to catch at least those 70 to be deliverered to the rear half lens, which also sees 70...
    You love to hear yourself talk, don’t you?

    Lachlan, there aren’t any reversed letters. I projected the image onto a 4x4 foot ground glass and measured the projected circle. It has a fairly sharp cutoff of illumination. The last inch of the image circle on either side is less defined than the rest, so like the comments by Sandy about the 450mm Nikkor M, it will cover but the corners will suffer a little in sharpness. Stopping down helped a little with sharpening the corners, but the image circle itself did not get larger. It gives roughly the same perspective as a 210mm lens on 8x10. I wanted a shorter lens for portraits so I didn’t have to stretch my bellows out all the way.

  9. #29
    Tin Can's Avatar
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    Re: 20x24 lenses

    Is there a difference with reversed lettering, besides I can't read it?

    I have one.

    Quote Originally Posted by Lachlan 717 View Post
    Does your copy have the reversed lettering inside the barrel ring?

    I had no idea that their coverage was so significant!
    where is the monolith

  10. #30
    Lachlan 717
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    Re: 20x24 lenses

    Quote Originally Posted by Randy Moe View Post
    Is there a difference with reversed lettering, besides I can't read it?

    I have one.
    No idea, Randy. Mine’s reversed.

    Haven’t mounted it yet, but might be a good substitute for my Nikkor 450mm that is a bit too close to my Claron 355mm on 7x17.

    Perhaps the subject of a new thread, though.
    Lachlan.

    You miss 100% of the shots you never take. -- Wayne Gretzky

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