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Ultrascopics vs UO orthos

Started by adamsdp, 01/19/2004 05:38PM
Posted 01/19/2004 05:38PM Opening Post

I am looking for eyepieces for binoviewing and was wondering which would be sharper and give better contrast for planet viewing, ultrascopics or uo orthos (old or new HD)? I have read good reports on both and need eyepieces in the 20 to 10 range. I have heard around 10mm the ultracopics get harder to use than an equivalent ortho and maybe I should mix orthos (9 & 12) and ultrascopics (20 & 15) if they are really close in performance.

Posted 01/20/2004 03:29AM #1
The 9mm UO measures 8mm e.r and the 7mm UO measures 6 e.r, but both eyepieces have the lens recessed nearly 2mm from the top of the conical barrel surface, so usable eyerelief is more like 6mm and 5mm respectively.

The Celestron 7.5mm Ultima measures 6.5mm e.r, but because of the recessed shaped of the top of the barrel, the lens surface is recessed nearly 3mm. So the usable e.r. on a 7.5 Ultima is only 3.5 to 4mm.

Posted 01/20/2004 06:21AM #2

I'd like to share an opinion as I have used the UO orthos exclusively for binoviewing. I decided when I got the binoviewer, I'd try to do it on the cheap, rather than pour top dollar into expensive eyepiece pairs.

The one thing I really like about the UO orthos, considering they have relatively short eye relief is the fact that the top of the barrels are conical (beveled?) rather than flat. It's like I know I'm bringing them close to my eyes, but it doesn't bother me as much. Maybe it's just psychological, but I love this feature of the design. Oh, and the sharp views in the orthos rock too!

Matthew Sherman