page_title: Refracting telescope
section_title: List of the largest refracting telescopes
hierarchical_section_title: Refracting telescope / List of the largest refracting telescopes
caption_attribution_description: "Chicago's Great Telescope." Yerkes. Interior of Manufactures and Liberal Arts Building. From Columbian Gallery: A Portfolio of Photographs of the World's Fair, The Werner Company. 1893. Digitial Identifier: GN90799d_CG_166w World's Columbian Exposition Collection at The Field Museum
context_page_description: A refracting telescope is a type of optical telescope that uses a lens as its objective to form an image. The refracting telescope design was originally used in spy glasses and astronomical telescopes but is also used for long focus camera lenses. Although large refracting telescopes were very popular in the second half of the 19th century, for most research purposes, the refracting telescope has been superseded by the reflecting telescope, which allows larger apertures. A refractor's magnification is calculated by dividing the focal length of the objective lens by that of the eyepiece.
  Refracting telescopes typically have a lens at the front, then a long tube, then an eyepiece or instrumentation at the rear, where the telescope view comes to focus. Originally, telescopes had an objective of one element, but a century later, two and even three element lenses were made.
  Refracting telescope is a technology that has often been applied to other optical devices such as binoculars and zoom lenses/telephoto lens/Long-focus lens.
context_section_description: Examples of some of the largest achromatic refracting telescopes, over 60 cm (24 in) diameter.
  Great Paris Exhibition Telescope of 1900 (1.25 m or 49 in) – dismantled after exhibition
  Yerkes Observatory (101.6 cm or 40 in)
  Swedish 1-m Solar Telescope (98 cm or 39 in)
  Lick Observatory (91 cm or 36 in)
  Paris Observatory Meudon Great Refractor (83 cm (33 in), + 62 cm (24 in))
  Potsdam Great Refractor (80 cm (31 in), + 50 cm (20 in))
  Nice Observatory (77 cm or 30 in)
  John Wall (76.20 cm or 30 in) dialyte refracting telescope - the largest refractor built by an individual, at Hanwell Community Observatory
  28-inch Grubb Refractor at Royal Greenwich Observatory, (71 cm or 28 in) aperture lens
  Great Refractor of Vienna Observatory, (69 cm or 27 in)
  Archenhold Observatory – the longest refracting telescope ever built (68 cm or 27 in × 21 m or 69 ft focal length)
  United States Naval Observatory refractor, (66 cm or 26 in)
  Newall refractor at the National Observatory of Athens (62.5 cm or 24.6 in)
  Lowell Observatory (61 cm or 24 in)
caption: The Yerkes Great refractor mounted at the 1893 World's Fair in Chicago; the tallest, longest, and biggest aperture refactor up to that time.
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