Two Surface Lenses

Discussion in 'Camera Building, Repairs & Modification' started by Mustafa Umut Sarac, Feb 12, 2017.

  1. Mustafa Umut Sarac

    Mustafa Umut Sarac Subscriber

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    Is there any two surface fully corrected lens design for order from a lens grind from a shop ?

    I am adding shafer 1980 two surface lenses paper from 37! years ago.
    find pdf

    Umut
     

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    Last edited: Feb 12, 2017
  2. AgX

    AgX Member

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    That article gives examples that do not employ lens elements but mirrors.

    Mirrors do not have dispersion, thus lack the two forms of chromatic abberation. But then one has to cope with peculiarities in beam path.
     
  3. AgX

    AgX Member

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    If you use an astro telescope of the Dobson type and attach to it your camera without camera lens and without the telescope eyepiece, then you are using a two-surface photographic lens.
     
  4. Dan Fromm

    Dan Fromm Member

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    If you read it all the way through, you'll find refracting lenses. Not that any of this matters. The OP has asked numerous questions about how to do things. I may have missed it/them, but I don't recall a single post by the OP reporting on a completed project. The OP proposes things for us to do and that's all.
     
  5. AgX

    AgX Member

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    But that is part of the game.

    This is not about starting or even completing projects, but about digging up interesting things.
    Among the heap of stuff Umut puts down at Apug are a few pearls.
     
  6. Nodda Duma

    Nodda Duma Subscriber

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    I've had a copy of this paper for years. It is a good summarizing document on two-surface designs within his field of expertise, but doesn't provide much detail. His references are more interesting.

    To fully correct (assuming you mean as an imaging objective), the answer is no. Think in mathematical terms: The number of variables available vs the number of aberrations.

    The Cooke Triplet provides the minimum number of variables to fully correct all third-order aberrations as well as focusing an image. Even then, higher order aberrations limit the lens speed.

    Two-surface mirror telescopes achieve correction over a limited field of view, but cannot fully correct all third order aberrations. Usually field curvature and distortion are left uncorrected. The speed of the scope (f/#) is limited by the need to control higher order aberrations.

    The Double Gauss is the minimum design form to correct all third order anerrations and control higher order aberrations at all lens speeds.
     
  7. Dan Fromm

    Dan Fromm Member

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    Thanks for the reply. I've never looked at the OP's posts from that angle.