An auxiliary lens, used mainly for photographic or CCD-imaging purposes. It reduces a telescope's effective focal length, allowing images to be taken much faster, and also gives a wider field of view. Some focal reducers may be used visually to obtain a wider field of view, but others are intended for photographic/CCD use only.
Related category OPTICS AND OPTICAL PHENOMENA
Home • About • Copyright © The Worlds of David Darling • Encyclopedia of Alternative Energy • Contact