Re: (IAAC) FWD: What should I buy? (rich field scopes)
At 10:53 AM 6/12/98 -0400, you wrote:
>>At 01:37 PM 6/8/98 -0400, Lew wrote:
>>>I also have a very wide-field eyepiece (about 55')
>>What eyepiece is this and don't you get terrible coma?
>No, I really don't! It's a 35mm Panoptic, which with a 20" f/5 gives about
>With an AFOV (apparent field of view) of 65 degrees on the Panoptic, this
>out to about 54' actual field and 7mm exit pupil.
>And, believe it or not, the views are ALWAYS both crisp and bright right to
>edge of that field. I generally mistrust expensive astrogizmos (I respect AP
>and TeleVue refractors, but would NEVER buy one - and don't even get me
>on Questar.) But there is a real good reason why TeleVue's Nagler and Panoptic
>oculars cost so much: they work! :)
I just got a 12 mm Nagler and have had one night to use it before we reached
zero darkness as we have now. It was a very impressive view, contrast was
much better than my 15 mm Plossl and if anything the field of view was
wider. I also got a second hand 4.8 mm Nagler a couple of months before.
This gives excellent contrast on deep sky objects or comets but for the moon
the contrast was much poorer than with a 4.5 mm Orthoscopic, quite
surprisingly so really but Naglers are deep sky eyepieces. The thought does
occur that this may be related to poor baffling in the scope and hence
greater intake of scattered light with the large field lens and wide angular
apeture of the Nagler so their reputation for poor planetary or lunar
contrast may relate more to the scope than the eyepiece.
For low power I have an eyepiece from a stereo microsope. I am not sure of
its FOV but it is probably about 40' judging from the moon. It works
reasonably well considering I got it free (Its microscope was stolen leaving
the spare eyepieces behind))
I think I will sell on the 4.8 mm as at X466 it is too high a power to be
easy to use with my Dobsonian and too expensive to keep for the odd time it
might be useful. I will probably go for a 7 mm. or stick with my 9 mm
Orthoscopic. What does anyone think?
Nick Martin, Bonnyton house, By Ayr, Ayrshire KA6 7EW ,Scotland, UK.
Longitude 55 24'56" Latitude 4 26' 00".
"Thou star of evening's purple dome
That lead'st the nightingale abroad,
And guid'st the pilgrim to his home."
To the Evening Star by T.Campbell