Amateur telescope making is the activity of building telescopes as a hobby, as opposed to being a paid professional. Amateur telescope makers build their instruments for personal enjoyment of a technical challenge, as a way to obtain an inexpensive or personally customized telescope, or as a research tool in the field of astronomy. Amateur telescope makers are usually a sub-group in the field of amateur astronomy.
A 22-inch Newtonian reflector sits in front of the clubhouse at Stellafane, home of the Springfield Telescope Makers
A 6-inch (15 cm) Newtonian reflector built by a school student on display at Stellafane
Grinding a mirror using an abrasive and a smaller tool over 300 mm mirror ("ATM Korenica 2006", in Korenica, Croatia)
Parabolic mirror showing Foucault shadow patterns made by knife edge inside radius of curvature R (red X), at R and outside R.
A telescope is a device used to observe distant objects by their emission, absorption, or reflection of electromagnetic radiation. Originally it was an optical instrument using lenses, curved mirrors, or a combination of both to observe distant objects – an optical telescope. Nowadays, the word "telescope" is defined as a wide range of instruments capable of detecting different regions of the electromagnetic spectrum, and in some cases other types of detectors.
The 100-inch (2.54 m) Hooker reflecting telescope at Mount Wilson Observatory near Los Angeles, USA, used by Edwin Hubble to measure galaxy redshifts and discover the general expansion of the universe.
17th- century telescope
Three radio telescopes belonging to the Atacama Large Millimeter Array
Hitomi telescope's X-ray focusing mirror, consisting of over two hundred concentric aluminium shells
