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Unread 03-08-2005, 10:00
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Alan Anderson Alan Anderson is offline
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Re: Simple telescope (lenses)

Quote:
Originally Posted by sanddrag
In a simple telescope (converging lenses, long focal length objective and short focal length eyepiece), why is the distance between the objective and the eyepiece approximately equal to the sum of their focal lengths?
It's simple, really. The first lens (objective) creates a virtual image of distant objects at its focus, and the second lens (eyepiece) is placed to magnify that virtual image by putting it at its focus.
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