Re: [ATM] very long focus objective

["Richard F.L.R. Snashall" <rflrs@rcn.com>]

Bob May wrote:
> Ah, I didn't even go so far as to notice the huge diameter of the first
> lens.  Is that really a 5" or so or is it really a 27" lens?  If the first
> lens needs to be that large then it will be collecting light from that much
> area (or a significant amount considering that the FOV will be a fraction of
> a degree for a real world application) and thus be considered to be a 27"
> lens.

For any single image point, it actually only uses a 5" spot of the outer
two lenses.

I didn't really think the wide field could be achieved without
a separation of the lenses (maybe not as bad as that example,
but still significantly sized).  However, with a plus/minus 12.5
degree field:

      R           t             G        D
     27.383       0.4         B270      5.6
    171.25        0.106
    -96.648       0.3         BaK4      5.6
     35.877       0.1
      inf         0.428                 4.97   STOP
    -54.73        0.4         B270      5.6
    -32.971    1198.151
  -1200                                 520    IMAGE

-- 

Rick S.

http://users.rcn.com/rflrs

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