| focusing glass | <microscopy> A hand magnifier, used at the focal plane of a camera, usually with the ground glass removed. Its purpose is to examine the image for critical focus. It is, as a rule, a low-power magnifier so mounted that it is in focus when supported on a piece of clear glass at the focal plane of the cam- era, for studying the image. It operates equally well on the aerial image. (05 Aug 1998) |
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