Question

what is theory of eye lens of an astronomical telescope?​

Answer 1

Answer:

An eyepiece, or ocular lens, is a type of lens that is attached to a variety of optical devices such as telescopes and microscopes. It is so named because it is usually the lens that is closest to the eye when someone looks through the device. The objective lens or mirror collects light and brings it to focus creating an image.

Answer 2

The Astronomical Telescope

Its length is equal to the sum of the focal lengths of the objective and eyepiece, and its angular magnification is -fo /fe , giving an inverted image. The astronomical telescope can be used for terrestrial viewing, but seeing the image upside down is a definite inconvenience.