Astrophysics (Index)About

angular magnification

(a magnification measure for a magnifier with an eyepiece)

The term angular magnification is used for magnifying instruments (telescopes, microscopes) that include an eyepiece. When viewing through an eyepiece, the apparent size is because light from two points a certain angle apart (without the telescope) appear to be coming from a greater angle apart when viewed through the telescope. The ratio of these angles is the telescope's angular magnification.

Often the term magnification is used meaning angular magnification, but in cases not involving an eyepiece, such as an opaque projector, magnification has the specific meaning of the ratio of the size of an image with the size of the object itself.

Further reading: