T3D Re: Telescope eyepieces

[erker@xxxxxxxxxxxxxx (Greg Erker)]

>Are there telescope eyepieces these days that have larger exit pupils and
>longer eye relief (than the eyepieces common 20 years ago)?  When I was
>involved in telescopy they were all computed for about 7mm exit pupils (the
>approximate size of dark-adapted eye pupils) to maximize the efficiency for
>low-luminance subjects at the expense of being unforgiving of eye
>placement.  The eye relief was also quite short (5-10mm).

  The Sirius Plossl's I referred to
don't say what their eye relief is.
But on the same site there are some
Pentax eyepieces that claim 20 mm
eyerelief. No mention of exit pupil
size though.

http://209.66.79.54/CATALOG/755/48726.HTM

  The Pentax 40 mm is a $300 item though.

Greg E.



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End of TECH-3D Digest 256
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