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View Full Version : Telephoto lens and focal length being longer that single lens.


copitlory8
Sep17-10, 04:40 PM
1. Why is a telephoto lens considered to have a longer focal length than that of a single convex lens?

A lens combination, such as a diverging and a convex lens, is referred to as a telephoto lens. Suggest why a telephoto lens is considered to have a longer focal length than that of a single convex lens.

pantaz
Sep17-10, 06:04 PM
Wiki appears to have as good an explanation as any...
http://en.wikipedia.org/wiki/Telephoto_lens