eighteenth-century astronomical equipment reflecting telescope

eighteenth-century astronomical equipment reflecting telescope

The main component of a reflecting telescope is a concave mirror (primary mirror), which reflects light to the focal point. Unlike refracting telescopes, reflecting telescopes use mirrors instead of lenses to focus light, which avoids chromatic aberration problems. Common reflecting telescope designs include the Newtonian and Cassegrain telescopes. Reflecting telescope design was further developed in the 18th century, particularly with large aperture and high power reflecting telescopes. The use of a parabolic mirror allows the light rays parallel to the optical axis of the objective lens to be accurately focused on the focal point, thereby greatly improving the image quality.
Old style Soviet audio speaker

Old style Soviet audio speaker