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8619Re: [tmboptical] Re: Monocentric eyepiece eye relief?

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  • Markus Ludes
    Apr 17, 2003
    • 0 Attachment
      Jim, excotic glas is not only way more expensive, its also a bit more difficult to polish. More info Tom Back can get to you

      best wishes
      ----- Original Message -----
      From: cjamescook
      To: tmboptical@yahoogroups.com
      Sent: Thursday, April 17, 2003 8:31 PM
      Subject: [tmboptical] Re: Monocentric eyepiece eye relief?

      > --- In tmboptical@yahoogroups.com, "Tony White <twhite@d...>"
      > <twhite@d...> wrote:
      > >
      > > A while back (message 6173) Tom said that the Steinheil
      > > monocentric's eye relief ratio was about .85. Assuming his
      > > designs won't vary from that, I get:


      > > I assume Markus or Tom will correct me if I'm wrong. :)

      --- In tmboptical@yahoogroups.com, "tmboptical <TMBoptical@a...>"
      <TMBoptical@a...> replied:

      > That was true with my first design that had a glass that was too
      > expensive to use in production.

      Okay, I'll bite on this one:
      On one hand, exotic glasses can be hundreds of dollars per kilo. This
      is expensive if you are building a primary objective. But here we are
      talking about eyepieces, where the lenses are fractions of an ounce
      (excuse the mixed units).

      So for us armchair opticians, living vicariously through your
      experiences and reports, how expensive can that be?

      Take this as a general question if you wish: Just how expensive do
      those exotic glasses get, generally speaking?

      -Jim Cook
      Bolton, Massachusetts, USA

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