List of largest optical refracting telescopes

Paris 1900 exposition refractor.

Here is a list of the largest optical refracting telescopes sorted by lens diameter. The largest refractor ever constructed was French. It was on display at the 1900 Paris Exposition. Its lens was stationary, prefigured so as to sag into the correct shape. The telescope was aimed by by the aid of a Foucault sidérostat, which is a movable plane mirror of diameter 6.56 feet, mounted in a large cast-iron frame. The horizontal tube was 197 feet long and the objective had 4.1 feet in diameter. The results were poor. When the year-long exposition was over, its builders were unable to sell it. It was ultimately broken up for scrap.

Observatory	Lens diameter	Focal length	Built	Comments
Paris 1900 Exposition (Paris, France)	1.25 m	57 m	1900	Fixed lens, total failure.
Yerkes Observatory (Williams Bay, Wisconsin, USA)	1.02 m	19.4 m	1897
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
Potsdam Observatory (Potsdam, Germany)	0.80 m	12.0 m	1899
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
Berlin Observatory (Berlin, Germany)	0.68 m	21 m	1896
Johannesburg Observatory (Johannesburg, South Africa)	0.67 m	10.9 m	1925
McCormick Observatory (Mount Jefferson, Virginia, USA)	0.67 m	9.9 m	1883
Royal Greenwich Observatory (Greenwich, London, England)	0.66 m	6.8 m	1897
U.S. Naval Observatory (Washington, DC, USA)	0.66 m	9.9 m	1873
Mount Stromlo Observatory (Mount Stromlo, Australia)	0.66 m	10.8 m	1925	Previously located in South-Africa. Relocated in Australia in 1952 Destroyed by bush fire on January 18, 2003