A Keplerian telescope is characterized by what specific lens arrangement?

A Keplerian telescope, also known as a refracting telescope, is designed with a specific arrangement of lenses to effectively magnify distant objects. The defining characteristic of this design is the use of a convex lens as the objective lens and a concave lens as the eyepiece.

The objective lens is responsible for gathering light from a far-away object and focusing that light to form a real image. This image appears at the focal point of the objective lens. The eyepiece, being a concave lens, then takes the light coming from this real image and further magnifies it, allowing the viewer to see a larger, virtual image that seems to be located closer than it actually is.

This combination of a convex lens as the objective and a concave lens as the eyepiece is what gives the Keplerian telescope its ability to produce high magnification and a wide field of view, making it a popular choice for astronomical observations.

Understanding the arrangement and functions of the lenses is crucial in recognizing the design principles underlying Keplerian telescopes and differentiating them from other types of optical instruments.