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UO Super-Erfles

Started by Zhimbo, 02/22/2003 01:49PM
Posted 02/22/2003 01:49PM Opening Post
There's essentially nothing on this forum about the University Optics Super-Erfles, and relatively little elsewhere on the web compared to other UO eyepiece models.

Looking at the ad in the latest S&T, I'm thinking that the 20mm is looking awfully attractive - I'd sell off my 20mm and 26mm Meade Plossl's if I can get the magnification of the 20mm plossl with nearly the TFOV of the 26mm, without compromising performance. Considering the UO Super Erfle is only about $80, seems like a deal that would pretty much pay for itself.

This'd be for a 6" f/8 system, so I doubt I'd be stressing the edges of the eyepiece FOV too much.

Does the collective wisdom of AstroMart have an opinion?
Posted 02/22/2003 03:21PM #1
Essentially true about the 20 swapped for the 25, but I don't know about the UO's. I have an old Celestron *Erfle* 20mm that is really a 25mm common ortho (Vixen) with the addition of a plano-convex extra field lens giving it a 20mm fl with the same true field as the 25 but with the corresponding wider AFOV. I also have a 6" f/8 newt and use this eyepiece alone or barlowed for most of my viewing, except for the occasional 32mm Konig type I (1.25" format) and a circle T 12.5mm ortho barlowed at the other extreme. I find this eyepiece has nearly the identical ortho performance as the 25mm mode (extra field lens removed) but with some very minor softening and distortion at the extreme edges. The UO's originally were advertized as a new 5-element format, and could very well be this ortho plus extra field lens configuration. BTW, this design was originated in the 1920's by Goerz using a meniscus field lens rather than a PCX with the usual abbe triplet and eye lens. Ron
Posted 02/23/2003 11:16AM #2
Comparing the UO super erfles to say a 1.25 UO konig, I'd pick the Super erfle. I own 20 and 25mm super erfles, as well as a 16mm konig. I'm much happier with the super erfles over the konig; comared to the SE's, the konig's eye relief is pretty poor, and I get much more ghosting in the Konig. Been looking for a used SE to replace the 16mm konig, but the SE's don't come up for sale too often (which says something on its own). From what I remember, the SE edge correction is right on line with the UO konigs, although sometimes with a slightly smaller FOV. The se's would probably be very nice in your 6" f/8 system, I'd reccomend them to anyone looking for good performance for that price range, especially over the 1.25" UO konigs.
Posted 02/23/2003 01:46PM #3
Jim, I think your thinking is right on target but I have never viewed thru a UO Super Erfle. I have an old Celestron 20mm erfle eyepiece, and I'd say it does everything 20mm and 26mm plossls do. At 20mm its not going to be a planetary eyepiece anyway in your 6" f/8 where the plossls excel and if the coatings are good on the erfle you should give up very little in light gathering.

To tell you the truth I've been eyeing the 16mm UO erfle for quite a while to use in a finder scope. I have an old 16mm flat top UO Koenig but the Koeing has zero eye relief, though it does offer sharp, wide views. The erfle design generally has more eye relief than the Koenigs so I've been considering taking a chance. Can anybody tell us first hand about the UO erfles?
Posted 02/25/2003 04:41PM #4
I had a 20mm UO super erfle and loved it. It was used in f/4.5 and f/10. It will do very very well in a 6" f/8 reflector or refractor.
Posted 02/26/2003 08:04PM #5
OK, I'm gonna go for it...first wide-field ocular that I can call my own. An important moment in a young man's life.