Quote:
Originally Posted by AstralTraveller
At the risk of wandering too far off the original topic, I notice you have a pretty complete set of UO HD orthoscopics. Any comments on them??
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Hi David,
I have the full set of UO HD orthos (5mm,6mm,7mm,9mm,12mm and 18mm). The Baader Genuine Orthos (BGO) are the same eyepiece with possibly slightly different coating specifications. For all practical purposes the two perform the same. The original UO volcano top orthos came in extra focal lengths (4mm, 5mm, 6mm, 7mm, 9mm, 12.5mm, 18mm and 25mm). Because of the top design the old volcano tops were slightly easier to use, but slightly inferior optically. The HD's (and BGO's) go a bit deeper and have better scatter and internal reflection control.
Like all orthoscopics, the UO HD's have a narrow FOV and short eye relief, which gets shorter as the focal length gets shorter. I have no problems using any of them with my glasses off. Optically they are very good. They offer 90% to 95% of the performance of the premium orthos like the Zeiss Abbe II's and the Pentax XO's, at a greatly reduced cost. They are a clear notch ahead of the cheaper Chinese/Taiwanese orthos and plossls. I would rate them as about the equal of Televue Plossls and maybe a touch ahead of the Takahashi LE's. They are much cooler in their colour tone than Televue Plossls. They "were" made in Japan and build quality on them was typical of all Japanese manufactured optics, very good. I believe they are no longer made following the Tsunami in Japan and any new items you might find, will be shelf stock. Over time you should be able to put together a set 2nd hand. They are certainly worth getting if you can find them and can't afford the very top end orthos, for lunar/planetary viewing etc, or can't afford premium widefields.
Cheers,
John B