History of the telescope a wider field of view than a classic Cassegrain. During the period 1850–1900, reflectors suffered from problems with speculum metal mirrors, and a considerable number of "Great Refractors" were built from 60 cm to 1 metre aperture, culminating in the Yerkes Observatory refractor in 1897; however, starting from the early 1900s a series of ever-larger reflectors with glass mirrors were built, including the Mount Wilson 60-inch (1.5 metre), the 100-inch (2.5 metre) Hooker Telescope (1917) and the 200-inch (5 metre) Hale telescope (1948); essentially all major research telescopes since 1900 have been reflectors. A number of 4-metre class (160 inch)
Large Zenith Telescope Large Zenith Telescope The Large Zenith Telescope (LZT) was a 6.0 m diameter liquid mirror telescope located in the University of British Columbia's Malcolm Knapp Research Forest, about east of Vancouver, British Columbia, Canada. (North of Maple Ridge.) It is one of the largest optical telescopes in the world, but still quite inexpensive. The telescope was completed in the spring of 2003. While a zenith telescope has the obvious disadvantage of not being able to look anywhere but at a small spot straight up, its simplified setup permits the use of a mirror consisting of a smoothly spinning pan filled