Assertion: eyepiece | /r/HasProperty | devised by al nagler
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text: this is the field of view of the original Nagler eyepiece, introduced to the market in 1980; this is, of course, the eyepiece devised by Al Nagler, and sold through TeleVue Optics, that sparked the current revolution in wide-field viewing (there are now a number of other brands of eyepieces with similar fields of view, such as 80 or 84 degrees);