A copyscope is type of
refracting telescope
A refracting telescope (also called a refractor) is a type of optical telescope that uses a lens (optics), lens as its objective (optics), objective to form an image (also referred to a dioptrics, dioptric telescope). The refracting telescope d ...
that can be made by hand rather than bought in which the
objective lens
In optical engineering, an objective is an optical element that gathers light from an object being observed and focuses the light rays from it to produce a real image of the object. Objectives can be a single lens or mirror, or combinations of ...
comes from an old
photocopy machine
A photocopier (also called copier or copy machine, and formerly Xerox machine, the generic trademark) is a machine that makes copies of documents and other visual images onto paper or plastic film quickly and cheaply. Most modern photocopiers us ...
, hence the origin of the name. The lenses usually come from defective or old photocopiers, allowing for the objective to be obtained for free or at a low cost. They are usually modest
diameter
In geometry, a diameter of a circle is any straight line segment that passes through the centre of the circle and whose endpoints lie on the circle. It can also be defined as the longest Chord (geometry), chord of the circle. Both definitions a ...
lenses, ranging from 50mm to 60mm, of short
focal length
The focal length of an Optics, optical system is a measure of how strongly the system converges or diverges light; it is the Multiplicative inverse, inverse of the system's optical power. A positive focal length indicates that a system Converge ...
, good for use in a portable, wide-field telescope, but unsuitable for higher magnifications. Given the use of good components, however, a copyscope can become a rich-field instrument capable of reaching many extended objects and even star fields.
History
The way in which copyscopes are constructed was first shown and explained in the May 1986 issue of ''
Astronomy Magazine
''Astronomy'' is a monthly American magazine about astronomy. Targeting amateur astronomers, it contains columns on sky viewing, reader-submitted astrophotographs, and articles on astronomy and astrophysics for general readers.
History
''A ...
'' by Ken Bird. Surplus photocopier lenses from 200 to 300 mm focal length along with
PVC pipe
Plastic pipe is a tubular section, or hollow cylinder, made of plastic. It is usually, but not necessarily, of circular cross-section, used mainly to convey substances which can flow—liquids and gases (fluids), slurries, powders and masses of sm ...
components for the tube and lens holder were used to build the copyscope described in the magazine.
Construction
Copyscopes usually use an objective lens sourced from a photocopier. Usually 50mm to 60mm in diameter, these lenses operate at low f/numbers (
f-ratio F-ratio or f-ratio may refer to:
* The F-ratio used in statistics, which relates the variances of independent samples; see F-distribution
* f-ratio (oceanography), which relates recycled and total primary production in the surface ocean
* f-number ...
of around f4 to f6) but cover a large field of view, and usually used at 1:1 conjugate.
Other parts of a copyscope include an eyepiece, typically with a barrel diameter of 1 1/4 inches with a focal length of 17 to 20 mm or longer. The availability of components over the Web allows enthusiasts to build a copyscope that can replace small
Newtonian design as their first serious telescope.
Benefits and Drawbacks
Pros
* When compared to the majority of telescopes that are offered in stores, the Copyscope gives a much larger field of view along with increased light gathering.
* If all the equipment necessary is at hand and the scope is built by the individual the result could more than likely be a very economical bottom-of-the-line telescope, as good as or even better than anything offered in the stores for the same value of price, however, in recent years some very good cheap telescopes have become available for little more than the cost of making a Copyscope.
Cons
* The lenses used for the telescope were not manufactured for this purpose, so they're not able to achieve a sharp focus at high magnification across the whole field of view. For wide-field, low power views of the heavens these telescopes work well and low power Copyscopes can make good finder scopes when used on larger telescopes.
See also
*
List of telescope types
The following are lists of devices categorized as types of telescopes or devices associated with telescopes. They are broken into major classifications with many variations due to professional, amateur, and commercial sub-types. Telescopes can be c ...
References
External links
Telescopes
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