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Telecompressor or focal reducer: Optical element to decrease the telescope's focal length and magnification (usually by a fixed percentage) and widen the field of view, providing opposite effects of a Barlow lens. Star Diagonal: Used to change the angle of the light coming out of a telescope, for easier viewing.
The first large telescope to use the design was the James Gregory Telescope of 1962 at the University of St Andrews. As of 2021, the James Gregory Telescope is also recognized as the largest Schmidt-Cassegrain. [4] The telescope is noted for its large field of view, up 60 times a full moon. [4]
The telescope is more a discovery of optical craftsmen than an invention of a scientist. [1] [2] The lens and the properties of refracting and reflecting light had been known since antiquity, and theory on how they worked was developed by ancient Greek philosophers, preserved and expanded on in the medieval Islamic world, and had reached a significantly advanced state by the time of the ...
A refracting telescope (also called a refractor) is a type of optical telescope that uses a lens as its objective to form an image (also referred to a dioptric telescope). The refracting telescope design was originally used in spyglasses and astronomical telescopes but is also used for long-focus camera lenses .
The 100-inch (2.54 m) Hooker reflecting telescope at Mount Wilson Observatory near Los Angeles, USA, used by Edwin Hubble to measure galaxy redshifts and discover the general expansion of the universe. A telescope is a device used to observe distant objects by their emission, absorption, or reflection of electromagnetic radiation. [1]
Maksutov's 1944 design was the first-published meniscus telescope design, and was published in the widely-read Journal of the Optical Society of America. [11] [12] [7] This led to professional and amateur designers almost immediately experimenting with variations, including Newtonian, Cassegrain, and wide-field camera designs.
Zerodur has both an amorphous (vitreous) component and a crystalline component. Its most important properties [21] are: . The material exhibits a particularly low thermal expansion, with a mean value of 0 ± 0.007×10 −6 K −1 within the temperature range of 0 to 50 °C.
One potential option was to insert corrective optics, lenses or mirrors in the telescope tube between the primary mirror and the secondary reflector. However the tube was too narrow for even the smallest astronaut to slither down it, leading to a search for a means of inserting the required corrective components into the tube. [4]