The diameter of the beam of light, which enters the eye through the eyepiece. The larger the exit pupil, the brighter the image.
System for the focusing of objects. Usually a focusing wheel or a rotating ring.
Determines the light intensity or brightness of the image. The larger the front lens diameter, the better the spotting scope performs in low light conditions.
There are different types of glass that offer certain advantages due to their specific characteristics.
Optical surfaces are metallized with coatings to increase the optical performance of the instrument.
Specifies how much larger an object appears compared to when viewed with the naked eye. For most spotting scopes, variable magnification zoom eyepieces are available.
Distinguishes the type or direction of the eyepiece position on a spotting scope.