List of largest optical refracting telescopes

Here is a list of the largest optical refracting telescopes sorted by lens diameter and year of construction.

The largest refractor ever constructed was French: an instrument sporting two interchangeable objective lenses (for visual and photographic use respectively) 1.25 m (49.2 in) in diameter, with a focal length of 57 m (187 ft). It was on display at the 1900 Paris Exposition. Due to the extreme focal length it was stationary. The telescope was aimed with the aid of a Foucault siderostat, a movable plane mirror 2 m (6.56 feet) in diameter, mounted in a large cast-iron frame. The horizontal steel tube was 60 m (197 feet) long; for focusing, the telescope’s eyepiece/plate end could be shifted five feet on rails. With the lowest power—500x—the field of view was 3 arc minutes. Due to its unfortunate location—right within the metropolis—and trouble with the siderostat, the results were poor and not suited for scientific use. When the year-long exposition was over, its builders were unable to sell it. It was ultimately broken up for scrap; the lenses are still stored away at the Paris Observatory.

Observatory	Lens diameter	Focal length	Built	Comments
Paris 1900 Exposition (Paris, France)	1.25 m	57 m	1900	Fixed lens, total failure, scrapped.
Yerkes Observatory (Williams Bay, Wisconsin, USA)	1.02 m	19.4 m	1897
Swedish Solar Telescope (Roque de los Muchachos Observatory, La Palma)	1 m	15 m	2002	Adaptive optics corrected refractor telescope
Lick Observatory (Mount Hamilton (California), USA)	0.91 m	17.6 m	1888
Paris Observatory (Meudon, France)	0.83 m + 0.62 m	16.2 m	1891	Double telescope
Astrophysical Observatory Potsdam (Potsdam, Germany)	0.80 m + 0.50 m	12.0 m	1899	Double telescope
Côte d'Azur Observatory (Nice, France)	0.76 m	17.9 m	1887
Allegheny Observatory (Pittsburgh, Pennsylvania, USA)	0.76 m	14.1 m	1914
Royal Greenwich Observatory (Greenwich, London, England)	0.71 m	8.5 m	1894
Vienna Observatory (Vienna, Austria)	0.69 m	10.5 m	1878
Archenhold Observatory (Berlin, Germany)	0.68 m	21 m	1896
McCormick Observatory (Charlottesville, Virginia, USA)	0.67 m	9.9 m	1883
U.S. Naval Observatory (Washington, DC, USA)	0.66 m	9.9 m	1873
Royal Greenwich Observatory (Greenwich, London, England)	0.66 m	6.8 m	1897
Yale Southern Station (Johannesburg, South Africa)	0.66 m	10.8 m	1925	Yale-Columbia Refractor (moved to Mount Stromlo Observatory in 1952), same telescope as following entry
Mount Stromlo Observatory (Mount Stromlo, Australia)	0.66 m	10.8 m	1925	Yale-Columbia Refractor - Previously located in South Africa. Relocated to Australia in 1952. Destroyed by bush fire on January 18, 2003
Belgrade Observatory (Belgrade, Yugoslavia)	0.65 m	10.55 m		Same instrument as at the Berlin Observatory
Berlin Observatory (Potsdam, Germany)	0.65 m	10.12 m	1914	The Berlin Observatory moved in 1913 to Potsdam, Babelsberg

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