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| A number used to compare the effectiveness of binoculars or spotting scopes used in low light. The twilight factor is found by multiplying the size of the objective lens (in mm) by the magnification and then finding the square root of that result. The larger the twilight factor, the more detail you can see in low light. A twilight factor of 17 or better if usually required for reasonable low light use. |
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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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