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  1. #1
    Simon's Avatar
    Simon Guest

    Default antique eye peice ?



    My father gave me an old eye piece a while ago, its got
    charles frank LTD Glasgow 1/4 inch RAMSDEN on it

    has anyone heard of them? are they still going?


    Simon



  2. #2
    Fleetie's Avatar
    Fleetie Guest

    Default antique eye peice ?

    > The Ramsden is a two-element eyepiece (identical plano-convex, curved

    As I recall, the lens furthest away from the eye is exactly in focus
    when viewed through the eye lens, meaning that any dust or defects in
    the other lens are in perfect view. Probably not an issue on an astro
    'scope, but it used to _really_ annoy me on a terrestrial telescope I
    once had.


    Martin
    --
    M.A.Poyser Tel.: 07967 110890
    Manchester, U.K. http://www.fleetie.demon.co.uk



  3. #3
    Stephen Tonkin's Avatar
    Stephen Tonkin Guest

    Default antique eye peice ?

    Fleetie <fleetie@fleetie.demon.co.uk> wrote:

    This is true for the achromatic condition. Another consequence is that
    the eye relief is zero. If the separation of the lenses is changed in
    order to give some (albeit tiny) eye relief, then the in-focus
    field-lens problem is also attenuated.

    Best,
    Stephen

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  4. #4
    Simon's Avatar
    Simon Guest

    Default antique eye peice ?

    well ive learnt something today,, thanks for that Stephen

    Simon
    "Stephen Tonkin" <news03@astunit.com> wrote in message
    news:KqTICuBug1R$Ewf4@astunit.com...









 

 

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