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Televue 18mm Radian 1.25" Eyepiece
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The Televue Radian Eyepiece achieves optimum full field sharpness and freedom from distortion.
- Incorporates exotic glass types and fully multi-coated for maximum performance properties.
- The TeleVue Radian Eyepiece has an apparent Field of View of 60º.
- Offers an outstanding 20mm of Eye Relief in a 1.25" barrel size.
- This TeleVue Radian Eyepiece is a 18mm focal length.
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Televue 18mm Radian 1.25" Eyepiece
 "In 1979, I had to sacrifice size, cost and weight in the original Nagler design to achieve what were previously mutually exclusive interests; extremely wide field, full field sharpness and comfortable eye-relief. Fortunately, users agreed that a lifetime of "spacewalk" viewing pleasure justified the investment. Fast forward to 1999. As the hobbyist population ages (along with me), more amateurs need eyeglasses. It was time to adjust the mix of parameters for observers who require or prefer long eye-relief. Under the framework of the "Nagler" design, the new field was set at 60° with a uniform 20mm eye-relief. Optimizing this new design with fully multicoated exotic glasses, we reached our new goal of full field sharpness with true orthoscopic linearity, highest contrast for critical planetary viewing, and compact size. The size and weight blend also makes the Radian preferable for small instruments and bino-viewers, and allows the convenience of being parfocal with other 1¼" Tele Vue eyepieces.." -- Al Nagler
By limiting the field to 60 deg. (a Radian = 57.3 deg.) and establishing a uniform 20mm eye-relief, TeleVue reworked the Nagler concept using the latest glass types to achieve optimum full field sharpness, freedom from distortion, freedom from ghosting (for critical planetary viewing) along with a unique adjustable eyeguard assembly which they called "Instadjust." Instadjust was developed from the need for proper eye position for non-eyeglass wearers. It is essential, since with Radian's long eye-relief, non-eyeglass wearers would easily tend to get too close to the eyepiece, resulting in vignetting the field, just as you would moving out from the exit pupil. The click-stop, Instadjust eyeguard permits fast, accurate positioning of the eye to the exit-pupil with maximum suppression of environmental stray light. Instadjust is topped off by a soft (for comfort and eyeglass protection) fold-down rubber eyeguard and protective cap.
Usual Televue features such as full multicoating, blackened lens edges, parfocalization, and grip-ring complement the Radian line. With a reasonable size, weight and cost, I anticipate the Radians will set a new benchmark in viewing pleasure for any person and any target within the eyepiece focal length range of 3mm-18mm. 18, 14, 12, 10, 8mm models have just 6-elements. 6, 5, 4, 3mm have 7 elements.
Televue Radian Eyepiece Reviews...
"What sets Radians apart from other long eye-relief, short-focal-length eyepieces is superb image quality. Even discerning planetary observers who customarily choose Plössl or orthoscopic designs are switching to Radian." -- Sky & Telescope, December 1999
Televue Product Number: ERD-18.0
All Televue products are available to ship world-wide from OPT, and effective July 1, 2008, are covered by a Five Year Worldwide Limited Product Warranty! Always be sure to save your original packaging materials should you need to return any Televue product for warranty or repair.
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