Your lens determines image sharpness, throw ratio, aspect ratio and maximum picture size. Fixed lenses are cheap and portable; zoom adds size flexibility; lens shift eases placement. Protect and clean ...

The F-number of a photographic lens is a measure of its light-gathering ability, and is expressed as its aperture diameter divided by its focal length. Lenses with low F-numbers are prized by ...

Projection lenses play a prominent role in modern society. When combined with a projector, these lenses allow people to view two-dimensional images on a screen by magnifying them and throwing them ...