The earliest and primitive telescopes and many amateur present day telescopes use telescope lens to collect and gather a greater amount of light as compared to the human eye. These focus on the light and make it easy to see the distant objects by making them appear clearer, brighter, and magnified. This kind of telescope is also called a refracting telescope.
Most of the refracting telescopes have 2 convex lenses. While Galileo developed the telescopes with a convex lens objective and a concave eye piece.
This device is used to form or create magnified images of the distant objects. Thus the telescope is undoubtedly one of the most critical investigative tools in astronomy.