Medical Definition of Negative focal length
1.
The focal length of a negative lens. Parallel rays impinging on a negative lens can be traced to a virtual focus which exists on the same side of the lens as the impinging rays. The distance from the second principal point of the lens to this second focal point is measured on the same side of the lens as is the object.
See: negative lens, focal length.
(05 Aug 1998)
Lexicographical Neighbors of Negative Focal Length
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