The refracting telescope has an aperture of 320 millimetres, a focal length of five metres and is located in the Wilhelm Foerster Observatory in the Berlin district of Schöneberg.

Juni 1892 in Friedenau), and the term "refractor" (Latin re = 'back' and frangere = 'refract') means that the telescope is made exclusively with light-refracting optical lenses and does not use mirrors or zone plates.

An electric clock was used for the largely automatic tracking of the telescope according to the hour angle of the object to be observed.

The lenses were made of high-quality glass from the Glastechnisches Laboratorium Schott & Genossen in Jena.

[2] Initially, it was not only available for research purposes, but primarily for the public in the observatory of the Urania on Invalidenstraße in Berlin, which was equipped with an electrically operated dome.

[5] However, the light pollution from the nearby railway facilities at Südkreuz proved unfavourable for night sky observations, so a new location was sought.

In November 1961, the foundation stone was laid for the Wilhelm Foerster Observatory built with funds from the Deutsche Klassenlotterie Berlin on the Insulaner in Berlin-Schöneberg, which was piled up after the war as a mountain of rubble to a height of a good 78 metres.

[8] In 1996 and 1997 the Bamberg refractor was overhauled by Gebhard Kühn at Zeiss in Jena,[9] and in 2020, it was equipped with a new electrically controlled tracking by the company 4H Jena-Engineering.

[12] The Bamberg Refractor was designed according to the principle of the Kepler telescope with an optical corrected lens system constructed with spherically ground lenses of flint and crown glass.

By combining the two glass types with different dispersion, the lens is achromatic, so that the blue and red light components have almost the same back focal length, which is, however, slightly larger than the cut width in the green.

[18] The telescope of the Bosscha Observatory in Indonesia, also called the Bamberg-Refraktor, has a focal length of seven metres, a diameter of 370 millimetres (lens speed = 19) and was first commissioned in 1927 in Berlin.