Rich Girard wrote:
> You all have me wondering what my dark adapted exit pupil size is. Is there
> a simple way to figure this out or would I need a optometrist to tell me? My
> Longest focal lenght eyepiece is Panoptic 22, in combination with 12.5 f5
> Portaball. I'm thinking about getting Nagler 31, but wouldn't want to do
> that if it's not optimal for me. BTW I'm 51 and require low power readers.
>
for sure, I find my 35mm ultrascopic (52 deg. AFOV) completely unusable
in my f/4.5 10" coulter. same eyepiece works great on a 2X shorty barlow.
the 35mm naked on the scope has incredibly bad astigmatism (or its
amplifying my eyes astigmatism, except my glasses don't seem to help).
going too far in and out of focus causes stars to smear H or V respectively.
the 7mm computation suggests that a 31mm is the upper limit for f/4.5...
since I'm 53 and my vision has significantly deteriorated from my youth,
I suspect 5mm is a better target for me, which would suggest a 22mm
eyepiece, or maybe 6mm for a 27mm eyepiece.
---
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Received on Wed Aug 27 16:24:48 2008
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