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Newtonian reflecting telescope

Newtonian reflecting telescope

Newtonian reflecting telescope


Place of Origin England

Date of Manufacture Circa 1955

A Newtonian reflector telescope with an 8 ½ inch mirror, constructed by F. Burnerd & Co, Putney, London.

Length of tube: 79 inches - 200 cm
Diameter of mirror: 8 ½ inches - 22 cm

The Newtonian telescope is a type of reflecting telescope invented by the scientist Sir Isaac Newton (1642–1727), using a concave primary mirror and a flat diagonal secondary mirror. Newton’s first reflecting telescope was completed in 1668 and is the earliest known functional reflecting telescope.

Advantages of the Newtonian design:

They are free of chromatic aberration found in refracting telescopes.

Since there is only one surface that needs to be ground and polished into a complex shape, overall fabrication is much simpler than other telescope designs (Gregorians, cassegrains, and early refractors had two surfaces that need figuring. Later achromatic refractor objectives had four surfaces that have to be figured).

A short focal ratio can be more easily obtained, leading to wider field of view.
The eyepiece is located at the top end of the telescope.

Combined with short f-ratios this can allow for a much more compact mounting system, reducing cost and adding to portability.

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