Re: Viewer eyepiece lenses

[P3D Greg Erker <erker@xxxxxxxxxxxxxx>]

>  I'm building a modified King Inn viewer. I'm planning to use a full
>spectrum flourescent tube and the best eyepiece lenses that I can find. Are
>there any sources of eyepieces other than Edmund? They seem to have only
>two element lenses. I need eyepieces somewhere between 60mm. focal length
>and 100mm. focal length and a diameter of 40mm. or larger.

  John B has the Edmund 40x80mm achromats and from what he has
said they are excellent and sufficiently large in diameter for
normal eyespacing.

  Not having $70 US per lens I bought the experimenter quality
36x82mm achromats from Edmunds (for about $35 ea). They are
AR coated. One of the lenses has a small edge chip (which
experimenter lenses are allowed to have). A bigger complaint
is that the lenses are somewhere between 34 and 35 mm, not the
36 claimed.  They are adequate in diameter if your lens holders
don't reduce the useable diameter.

  Other ideas are to look for full frame MF loupes. Pentax and
others make them. I don't know if the focal length will be in
the range you desire but the optical quality could be very high
if you are willing to buy the best loupes.

Good luck - Greg E.



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