Object glass (or object lens)The large lens of a pair of binoculars or a telescope. With 8 X 40 binoculars the magnification is eight times and the diameter of the object glass is 40 millimetres. The lens which is placed to the eye is part of the eyepiece.
Search Bird Dictionary
From Peter Weaver's Birdwatcher's Dictionary
Copyright © 1981 by Peter Weaver