aperture

aperture

The size of the primary optical surface of an astronomical instrument (telescope), usually given in inches, centimeters, or meters. In the case of a reflecting telescope, the aperture usually refers to the size of the main mirror; in the case of a refracting telescope (of which binoculars are one example), the aperture refers to the size of the primary lens (which in binoculars is usually given in millimeters).

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Industry/Domain: Astronomy
Category: General astronomy
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