The Televue Radian Eyepieces

I had a chance to try the 4, 6, 10, and 14mm Televue "Radian" eyepieces indoors when I met Al and Dave Nagler this past October, 1998 at a convention. I then bought the 10, 14, 8 and 3mm units and will review them below.

Written mainly 11/98, updated through Oct., 1999:

"............at the show, I had a 15mm Panoptic on hand, and a 5mm Takahashi LE ED on hand to compare with them. The Radian's were bigger than the 15mm Panoptic, in fact, a tad larger than a 19mm Panoptic. They are similar in size and appearance to the 32mm Televue Plossl, but vary from 4mm (largest) to 14mm (smallest). As has been reported by others on the newsgroup sci.astro.amateur these are fabulous eyepieces with just one small drawback.

Contrast amazingly seemed a bit better than the 15mm Panoptic when comparing with the 14. Contrast was noted to be high on all the ones I tried, with no ghost reflections, but I was trying them indoors on lights, dust, birds, etc... not on the night sky. The 20mm eye relief, and it's "click-stop" eyeguard, were admittedly inspired by the Pentax XL eyepieces which have long been a favorite of mine. Unfortunately, the Pentax eyeguard needs to be screwed up and down, which takes forever when switching between your glasses and/or observers. The click stop eyeguard of the Radians on the other hand, made for almost instant gratification when switching between my glasses, and viewing sans-glasses.

The 4mm, and 6mm were 7 elements, the 10mm, and 14mm.. 6 element eyepieces. The apparent field of view was at least the rated 60 degrees. The sharpness at the edge of field was amazing through the f/7 85mm Televue scope. There wasn't even a hint of losing any definition at the edge of any of the Radian's field. In addition, unlike the Panoptic line, straight lines stay straight - there is no "pin-cushion" distortion noted.

The only (minor) problem I ran into was the advent of "blackout areas" if the eyecup was not perfectly adjusted. Televue provides a "pupil guide" that helps you put your eye in the right place, to avoid that problem.

OUTDOOR REPORT, 3, 8, 10 and 14mm Radian eyepieces, Nov 1998 - Oct 1999.
I have had the pleasure of owning these eyepieces for a few months now, and have come to the conclusion that they are the best overall eyepieces I have ever owned. The click stop eyeguards work very well and allow me to optimize use in-a-flash for glasses-no glasses wear. The eyeguards are a bit looser on the more recent ones I have bought, but are still functional.  I preferred the stiffer earlier models.

The Radians are more convenient to use than the bulkier Pentax XL line (which I love performance wise) where you have to screw the eyecup up and down which takes awhile. Contrast and planetary performance has been superb, so has light throughput. Objects are sharp right to the very, very edge of field. All objects look their best through these eyepieces. Particularly impressive is the performance of the 3mm Radian which deserves special mention. The eye relief is so huge for a 3mm eyepiece, that there was no awareness of it being different than any other kind of eyepiece in terms of comfort of use. In fact, using it in two scopes with focal lengths near 1000mm, it worked out very well on Mars, which was shrinking in size, and needed the boost to over 300 power. Mars remained bright and crisp.. through to the edge of field. The only negatives reported to me have been an occasional ghost reflection, and also lack of color purity towards the edge of field. I have noticed that they do exhibit some false color as bright objects are brought towards the edge of field. These are the best all-around eyepieces though that I can think of.. sport the wide field but wonderful planetary performance.

Todd Gross

ANOTHER IMPRESSION OF THE RADIAN EYEPIECES from DAVE MITSKY
 

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