equivalent focal length


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length, equivalent focal

In an optical system composed of more than one lens, it is the linear distance separating the principal focus from the corresponding principal point. It is usually the most important quantity in the specification of an optical system as in objectives, eyepieces, etc. See principal focus; equivalent power.
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5 mm to super-telephoto 765 mm (both equivalent focal lengths in 35mm 135 format), the L830 has a very compact body measuring approximately 111 x 75.

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