This photo is an example of a typical equipment setup for me when doing Astrophotography. It consists of a Borg 101ED f/4.1 imaging scope using a QSI 683ws CCD. Focusing is done with a FeatherTouch focuser controlled with a MicroTouch motorized wireless focuser. Guiding is done with a Borg 45ED and a Lodestar guide camera. The mount is a Paramount MX on a Pier Tech II pier. Everything is housed in a Pier-Tech Telestation 5 Split roof automated observatory.
To see the observatory in an Automated open/close routine click on this video link: http://youtu.be/4RkObiE18TM Astrophotography
is a specialized type of photography that entails recording images of astronomical objects and large areas of the night sky. The first photographs of an astronomical object (the moon) were taken in the 1840s, but it was not until the late 19th century that advances in technology allowed for detailed stellar photography. Besides being able to record the details of extended objects such as the Moon, Sun, and planets, astrophotography has the ability to image objects invisible to the human eye such as dim stars, nebulae, and galaxies. This is done by long time exposure since both film and digital cameras can accumulate and sum light photons over these long periods of time. In professional astronomical research photography revolutionized the field, with long time exposures recording hundreds of thousands of new stars and nebulae that were invisible to the human eye, leading to specialized and ever larger optical telescopes that were essentially big “cameras” designed to collect light to be recorded on film. Direct astrophotography had an early role in sky surveys and star classification but over time it has given way to more sophisticated equipment and techniques designed for specific fields of scientific research, with film (and later astronomical CCD cameras) becoming just one of many forms of sensor.
Astrophotography is a large sub-discipline in amateur astronomy where it is usually used in to record aesthetically pleasing images, rather than for scientific research, with a whole range of equipment and techniques dedicated to the activity.
With only a few exceptions, almost all astronomical photography employs long exposures since both film and digital imaging devices can accumulate and sum light photons over long periods of time. The amount of light hitting the film or detector is also increased by increasing the diameter of the primary optics (the objective) being used. Urban areas produce light pollution so equipment and observatories doing astronomical imaging have to be located in remote locations to allow long exposures without the film or detectors being swamped with stray light.
Since the Earth is constantly rotating, telescopes and equipment have to be rotated in the opposite direction to follow the apparent motion of the stars overhead (called diurnal motion). This is accomplished by using either equatorial or computer controlled altazimuth telescope mounts to keep celestial objects centered while the earth rotates. All telescope mount systems suffer from induced tracking error due to imperfect motor drives and mechanical sag of the telescope. Tracking errors are corrected by keeping a selected aiming point, usually a bright guide star
, centered during the entire exposure. This guiding is done through a second co-mounted telescope called a "guide scope
" or via some type of "off-axis guider
", a device with a prism or optical beam splitter that allows the observer to view the same image in the telescope that is taking the picture. Guiding used to be done manually throughout the exposure with an observer standing at (or riding inside) the telescope making corrections to keep a cross hair on the guide star. Since the advent of computer controlled systems this is accomplished by an automated systems in professional and even amateur equipment.
Astronomical photography is one of the earliest types of scientific photography and almost from its inception it diversified into subdisciplines that each have a specific goal including star cartography, astrometry, stellar classification, photometry, spectroscopy, polarimetry, and the discovery of astronomical objects such as asteroids, meteors, comets, variable stars, novae, and even unknown planets. These all require specialized equipment such as telescopes designed for precise imaging, for wide field of view (such as Schmidt cameras), or for work at specific wavelengths of light. Astronomical CCD cameras may use cryogenic cooling to reduce thermal noise or allow the detector to record images in other spectra such as in infrared astronomy. Specialized filters are also used to record images in specific wavelengths.