TeleVue Radian

More Information  · Recommended Accessories  · Images of Some Features Price $237.00 $250.00 SAVE: $13.00 (5%) List Price $295.00 Field of view 60° Eye Relief 20mm Focal Length 4mm Number of optical elements 7 Barrel Size 1.25" Weight 9 oz Warranty 5 years Telescope Eyepiece Formula To calculate the magnification and approximate actual field of view of this eyepiece on your telescope, enter the focal length of your telescope below and press the "Calculate" button. mm

It will generally be of marginal utility for regular use with long focal length refractors, reflectors, or catadioptric scopes under average seeing conditions. Using it with a 2000mm 8" f/10 Schmidt-Cassegrain, for example, will result in 500x (63x per inch of aperture) and a 0.4mm exit pupil (about 1/64th of an inch across). Both of these are slightly past the rule of thumb maximum values of 50-60x per inch of aperture and a 0.5mm exit pupil, but are usable by a reasonably experienced observer under very good seeing conditions. Average seeing conditions would generally keep these maximum values from being attainable