# Keplerian Telescope

The Keplerian Telescope, invented by Johannes Kepler in $$1611,$$ is an improvement on Galileo's design. It uses a convex lens as the eyepiece instead of Galileo's concave one. The above is a schematic design of the Keplerian Telescope, where the center of the objective and eyepiece lenses are $$L_1$$ and $$L_2$$, respectively. When the distance between them is $$L$$, the image of the moon becomes the sharpest. If the focal length of the eyepiece lens is $$f,$$ then which of the following statements is NOT correct?

a) The focal length of the objective lens must be larger than $$L.$$

b) The image shown by the eyepiece lens is a virtual image.

c) The distance between the image created by the objective lens and the center of the eyepiece lens is smaller than $$f.$$

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