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Ever since Galileo Galilei adapted a Dutch invention for astronomical use, astronomical telescope making has been an evolving discipline. Many astronomers after the time of Galileo built their own telescopes out of necessity, but the advent of amateurs in the field building telescopes for their own enjoyment and education seems to have come into prominence in the 20th century.
A copyscope is type of refracting telescope that can be made by hand rather than bought in which the objective lens comes from an old photocopy machine, hence the origin of the name. [1] The lenses usually come from defective or old photocopiers, allowing for the objective to be obtained for free or at a low cost.
A Schmidt corrector plate is an aspheric lens which corrects the spherical aberration introduced by the spherical primary mirror of the Schmidt or Schmidt–Cassegrain telescope designs. It was invented by Bernhard Schmidt in 1931, [ 6 ] although it may have been independently invented by Finnish astronomer Yrjö Väisälä in 1924 (sometimes ...
The force of gravity (red), the buoyancy force (green), and the resultant centripetal force (blue) In the following discussion, represents the acceleration due to gravity, represents the angular speed of the liquid's rotation, in radians per second, is the mass of an infinitesimal parcel of liquid material on the surface of the liquid, is the distance of the parcel from the axis of rotation ...
Foucault testing is commonly used by amateur telescope makers for figuring primary mirrors in reflecting telescopes. [5] [6] The mirror to be tested is placed vertically in a stand. The Foucault tester is set up at the distance of the mirror's radius of curvature (radius R is twice the focal length.) with the pinhole to one side of the centre ...
A Fresnel imager is a proposed ultra-lightweight design for a space telescope that uses a Fresnel array as primary optics instead of a typical lens. It focuses light with a thin opaque foil sheet punched with specially shaped holes, thus focusing light on a certain point by using the phenomenon of diffraction.
This had a visual objective lens of 32.7 inches on one tube, and alongside it another tube with a lens of 24.4 inches intended for photographic work. [31] An example of converting to photographic work with a third corrector lens is the Lick telescope. [31] A 33-inch corrector lens was used to convert this telescope for photography. [31]
In 1982, club president Merry Edenton-Wooten had the idea of using surplus Xerox copier lenses as objectives for beginner scopes. The "copier lens telescope" idea spread across the world, promoted by surplus suppliers like JerryCo and C&H Sales, and led to the construction of thousands of high quality rich field telescopes at very affordable ...