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This Ralph Dakin doublet design is considered by many professional astronomers to be the Rolls-Royce of Barlows. It has a magnification of 2.4x for non-repeating eyepiece powers. A non-marring nylon thumbscrew holds eyepieces securely in place. The lenses are antireflection coated, but not multicoated. One reason not to multicoat is to eliminate or greatly reduce a phenomenon known as "narrow angle light scatter." Multicoatings have more narrow angle scatter than single layer coatings. You can see this effect on bright objects like Venus, Mars, or Jupiter, where scattered light can greatly interfere with low contrast detail. You can also notice a difference in the background darkness immediately surrounding a bright object, which is especially important for planetary or close binary star observing. In addition, lunar detail such as the bands of Aristarchus are usually better defined. The barrel has internal antireflection threading to further improve contrast. Its 4.25" length allows its use in many star diagonals. The Dakin Barlow performs best with scopes f/6 and above.
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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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