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These economy eyepieces are computer-optimized versions of the three-lens Kellner design. They’re designed for low to medium high power use on telescopes with focal ratios down to f/6, but are at their best at focal ratios above f/8. They have acceptable to good sharpness at the center of the field, although with some astigmatism at the edges. They are fully coated, with good color correction. They have moderate ghosting, which is a drawback in serious lunar and planetary observing. Field curvature is noticeable, emphasizing the coma in fast focal ratio reflectors. The telescope focal plane lies on the surface of the eyepiece lens nearest telescope (the field lens), so that any dust on the lens is in sharp focus, requiring a little extra care in keeping the eyepiece clean. They are threaded for standard color and nebula filters. While not the optical equal of more expensive Plössl designs, they’re a good choice for general observing for the astronomer on a budget.
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Terms of Sale | PRIVACY POLICY 7/1/2004 | Fine Print
Toll-Free Telephone Astronomics: 800-422-7876; Christophers, Ltd.: 800-356-6603
Alternate Telephone: 405-364-0858 24 Hour Fax Line: 405-447-3337
Telephone Hours: Monday-Friday 8 AM - 9 PM CST
Saturday Noon - 5 PM CST
Store Hours: Monday-Friday 9 AM - 5 PM CST
Saturday Noon - 5 PM CST
Astronomics / Christophers, Ltd.
680 S.W. 24th Ave.
Norman, OK, 73069
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