| This medium focal length TeleVue Radian eyepiece is usable with any scope type, under virtually any seeing conditions – from fair to superb. It provides the same wide field of view as a 13mm Nagler (although at lower power), but with almost twice the brightness due to its larger exit pupil (and at a lower price). An f/4.5 Dobsonian will yield a 4mm exit pupil, getting into the rich field observing range. With short focal length refractors, it’s a low power, very wide field eyepiece. With the 480mm focal length TeleVue Pronto, for example, it provides 27x, a 2.65mm exit pupil, and a huge 2.22 degree field that’s over four times as wide as the Moon. With its long 20mm eye relief, even those who must wear eyeglasses while observing will see the entire wide field of this eyepiece and the splendors it can hold. It is also truly excellent for medium magnification lunar, planetary, and globular observing with long focal length refractors, reflectors, or catadioptric scopes. |
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