I am currently using a TV Panoptic 3mmm. 2" EP which has a 68º fov. this gives me 25X with my 880 f/l 102 refractor. Would a TV Nagler 31mm. with the 82º field be a better choice for my "finder" EP the Nag. will give me 28X with a wider field? JM
35mm vs 31mm.
Started by Midnight Sun, 09/02/2006 08:17PM
Posted 09/02/2006 08:17PM
Opening Post
Posted 09/02/2006 08:41PM
#1
According to http://www.televue.com/engine/page.asp?ID=144
the field stop of the 35 Pan is 38.7mm while that of the
31 Nagler is 42mm. So the absolute field of the 31mm will
be wider, but the difference is not huge.
If its really just a finder eyepiece, you might also
consider something like the 1RPD 30mm 80 deg which has
a 41mm field stop. The field edge is not as sharp
as the others, but at half the weight and about $95,
its hard to complain much.
http://www.astrobuffet.com/ab/30mm.html
the field stop of the 35 Pan is 38.7mm while that of the
31 Nagler is 42mm. So the absolute field of the 31mm will
be wider, but the difference is not huge.
If its really just a finder eyepiece, you might also
consider something like the 1RPD 30mm 80 deg which has
a 41mm field stop. The field edge is not as sharp
as the others, but at half the weight and about $95,
its hard to complain much.
http://www.astrobuffet.com/ab/30mm.html
Posted 09/05/2006 02:16PM
#2
In an f 9.8 refractor (sounds like a televue 102, or an achromat), there is very little significant difference between the two eyepieces. The panoptic gives you 2.4+ degrees true field, the Nagler 2.6. That's a broad field for all but a couple of objects under very dark skies. The exit pupil is not an issue in either case. They're both pretty heavy as in rebalancing.
I would stick with what you have.
I would stick with what you have.
