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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 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 ...
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.
If the right lens is inserted, so that the chosen distance roughly equals the distance of the drawing surface, both images can be viewed in good focus simultaneously. [ citation needed ] If white paper is used with the camera lucida , the superimposition of the paper with the scene tends to wash out the scene, making it difficult to view.
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 ...
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.
The lens, made by Cooke, was first used in 1865 in a telescope built by Norman Lockyer. Cooke later rebuilt the telescope in its present form in 1871. The telescope was positioned in several locations before being moved to Sidmouth in 1912, where it remains. Lockyer used this telescope to discover helium in the solar corona. It was restored in ...
Their first telescopes (4.5" (114 mm) -Newtonians) were distributed by Celestron and Tasco. In 1993, the first refracting telescopes were produced. In 1999, the brand Sky-Watcher was established by Synta Taiwan to sell optics produced by Suzhou Synta. The head office was in Richmond, British Columbia, Canada.