|
Astrophotography is a specialised type of photography that entails making photographs of astronomical objects in the night sky such as planets, stars, and deep sky objects such as star clusters and galaxies. Lens and mounting of a large format camera Wikibooks has more about this subject: Photography Photography is the process of making pictures by means of the action of light. ...
A planet is generally considered to be a relatively large mass of accreted matter in orbit around a star that is not a star itself. ...
The Pleiades star cluster A star is a massive body of plasma in outer space that is currently producing or has produced energy through nuclear fusion. ...
Deep sky object (DSO) is a term used often in amateur astronomy to denote objects in the night sky other than solar system objects (such as planets, comets and asteroids), single stars and multiple star systems. ...
Astrophotography is used to reveal objects that are too faint to observe with the naked eye, as both film and digital cameras can accumulate and sum photons over long periods of time.
Astrophotography poses challenges that are distinct from normal photography, because most subjects are usually quite faint, and are often small in angular size. Effective astrophotography requires the use of many of the following techniques:
- Mounting the camera at the focal point of a large telescope
- Emulsions designed for low light sensitivity
- Very long exposure times (one hour or more is common)
- Tracking the subject to compensate for the rotation of the Earth during the exposure
- Gas hypersensitizing of emulsions
- Use of filters to reduce background fogging due to light pollution of the night sky.
The first astrophoto is attributed to John William Draper, who took a photo of the moon in 1840. His son, Henry Draper, later became the first person to photograph the Orion Nebula in 1880, which was essentially the first deep sky astrophoto. Since the early 1990s, most professional observatories switched to using CCD devices for astronomical imaging. They have numerous advantages, with increased sensitivity and more linear response. The principle disadvantage is a significant reduction in the field of view. CCDs require specific modifications for best effect in the low light conditions of astronomy, such as: The shutter speed dial of a Fujika STX-1. ...
John William Draper (1811 - 1882), U.S. (English-born) chemist was a historian & photographer. ...
Crust composition Oxygen 43% Silicon 21% Aluminium 10% Calcium 9% Iron 9% Magnesium 5% Titanium 2% Nickel 0. ...
1840 is a leap year starting on Wednesday (link will take you to calendar). ...
Henry Draper (March 7, 1837 – November 20, 1882) was an American doctor and astronomer. ...
The entire Orion Nebula in visible light Optical images reveal clouds of gas and dust in the Orion Nebula; an infrared image (right) reveals the new stars shining within. ...
1880 was a leap year starting on Thursday (see link for calendar). ...
Deep sky is a term used by amateur astronomers to describe mostly faint objects outside the solar system like star clusters, nebulae and galaxies; compare with deep space. These objects are hundreds to billions of light years distant. ...
The 1990s decade refers to the years from 1990 to 1999, inclusive, the last decade of the 20th Century. ...
A specially developed CCD used for ultraviolet imaging in a wire bonded package. ...
Your field of view is that part of the observable world that you are able to see at any given moment. ...
- cryogenic cooling to reduce thermal noise
- compensation for non-uniform pixel sensitivity
- biasing
Emulsion based astrophotography remains popular with amateur astronomers, but even here CCD imaging is becoming relatively cheap and is starting to replace wet photography. This article needs to be cleaned up to conform to a higher standard of quality. ...
A pixel (pix, 1932 abbreviation of pictures, coined by Variety headline writers + element) is one of the many tiny dots that make up the representation of a picture in a computers memory. ...
It has been suggested that this article or section be merged with Skygazing. ...
Simple astrophotography
Although the description above suggests that astrophotographs can be made only with expensive equipment by photographers with extensive experience, in fact surprisingly good quality, wide-angle photographs of the night sky can be made by almost anyone using readily available single lens reflex 35 mm traditional film or digital cameras. What is always required, however, is that the photographer travel far away from the bright, light-polluted skies of major cities or towns. This will ensure that the sky is dark enough so that the photograph will not be completely washed out and ruined by bright urban light pollution.
Simple wide-angle astrophotographs of constellations containing familiar star patterns (such as Ursa Major, Orion, Sagittarius and others) can be made as follows:
1. Mount the camera on a sturdy tripod. Load the camera with high-speed (at least ISO 200) film, or set the digital camera speed to between 200 and 800.
2. Turn off the autofocus mechanism, and manually set the focus ring of the lens to infinity.
3. Set the shutter speed to either the "bulb" setting, or a range of settings between about 2 and 30 seconds.
4. Point the camera at the desired area of the sky, trip the shutter (preferably using a cable release, or the camera's self-timer in order to minimize vibration), and keep the shutter open for the desired length of time.
5. For best results, "stop down" the lens from its maximum aperture (often f/1.4, 1.8 or 2.0 for film cameras) at least 1/2 to one full stop. This will (i) reduce the uneven lighting across the image known as "vignetting", and (ii) reduce aberrations in the star images that can make them appear bloated or misshapen.
Earth's rotation will cause the night sky to appear to turn overhead. The result is that, using a stationary camera, within a short period of time the stars will appear as streaks of light on the photograph, rather than the sharp, point sources of light that we see with our eyes. Using a standard 50 mm lens on a 35 mm camera, stars will begin to streak across the film plane after about 30 seconds. Although very striking photographs can be made using exposures of minutes or hours - so as to deliberately show long star trails - most astrophographers either use short exposures on a stationary mounted camera, or else use a motor-driven telescope mount, in order to keep the stars as points of light in the final photograph.
See also David Malin (born 28 March 1941) is a British-Australian astronomer and photographer. ...
Invented by the Russian optician Dmitri Maksutov (1896-1964), the Maksutov-Cassegrain reflecting telescope is a type of catadioptric telescope that uses a either a spherical or parabolic primary mirror in conjunction with a meniscus-shaped corrector plate at the entrance pupil in order to correct spherical aberration. ...
The National Geographic Society - Palomar Observatory Sky Survey (NGS-POSS) is a major photographic survey of the night sky completed at Palomar Observatory in 1958. ...
Photographic plates were one of the earliest forms of photographic film, in which a light-sensitive emulsion of silver salts was applied to a glass plate. ...
Lens and mounting of a large format camera Wikibooks has more about this subject: Photography Photography is the process of making pictures by means of the action of light. ...
External links - The Early History of Astrophotography
- Amateur Astrophotographies of The Messier Objects
| 
Feeds |
Contact