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Astrophotography
                                     

★ Astrophotography

Astrophotography is photography of celestial objects, celestial events and plots of the night sky. The first photograph of an astronomical object was taken in 1840, but it was not until the late 19th century that advances in technology allowed for detailed stellar photography. In addition to the ability 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 achieved by long exposures with film and digital cameras can accumulate and sum light photons over these long periods of time.

Photography revolutionized the field of professional astronomical research, with long exposure 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 record light by using photographic plates. Astrophotography had an early role in the filming of the starry sky and star classification but over time it has given way to more sophisticated equipment and techniques designed for specific fields of research with image sensors becomes just one of many forms of sensor.

Today, astrophotography, basically a subdiscipline in Amateur astronomy, usually looking for aesthetically pleasing images and not scientific data. Fans use a wide range of special equipment and technology.

                                     

1. Overview. (Обзор)

With rare exceptions, astronomical photography employs long exposures since both film and digital imaging devices can accumulate and photons of light for long periods of time. The amount of light reaching the film or detector is also increased by increasing the diameter of the primary optics used. Urban areas produce light pollution so equipment and observatories doing astronomical images are often located in remote locations to allow long exposures without the film or detectors being flooded with diffused light.

Since the Earth is constantly rotating, telescopes and equipment are rotated in the opposite direction to follow the apparent motion of the stars overhead called diurnal motion. This is achieved through Equatorial or computer controlled altazimuth telescope mounts to keep celestial objects centered while the Earth rotates. All systems of the telescope, the mount suffer from tracking error induced due to the imperfection of the actuators, the mechanical SAG of the telescope and of atmospheric refraction. Tracking errors were corrected, saving the selected aiming point, usually the guide star, center it in the whole exposition. Sometimes, as in the case of a comet the object to be imaged is moving, so the telescope must be constantly focused on this object. This guidance is done through a second co-mounted telescope called a "guide area" or through some type of off-axis guide ", a device with a prism or optical beam Splitter that allows the observer to see the same image in the telescope that took the picture. Guiding was formerly done manually throughout the exposure with an observer standing on or riding inside the telescope making corrections to keep the crosshairs on the stars. With the advent of computer-controlled systems this is achieved using the automated system in professional and even Amateur equipment.

Astronomical photography was one of the earliest types of scientific photography and almost from its inception it was divided into sections, each of which has a specific purpose, including star cartography, astrometry, stellar classification, photometry, spectroscopy, polarimetry, and the discovery of astronomical objects such as asteroids, meteors, comets, variable stars, new and even unknown planets. They often require specialized equipment such as telescopes designed for precise image, wide field of view, such as Schmidt cameras, or to work at specific wavelengths of light. Astronomical CCD camera can cool the sensor to reduce thermal noise and to provide a detector for recording images in other spectra, such as infrared astronomy. Specialized filters are also used to record images at a certain wavelength.

                                     

2. History. (История)

The development of astrophotography as a scientific tool was pioneered in the mid-19th century, for the most part of experimenters and Amateur astronomers, or so-called "pundits". Because of the very long exposures needed to capture relatively weak astronomical objects, many technological problems must be overcome. These include telescopes rigid enough so they dont SAG out of focus during the exposure, building clock drives that could turn the telescope at a constant level, and the development of ways to accurately keep the telescope aimed at a fixed point over a long period of time. Early photographic processes also had limitations. Daguerreotype process was far too slow to record anything but the brightest objects, and the wet plate collodion process impact society at the time the plate could stay wet.

The first known attempt at astronomical photography Louis Jacques Mande Daguerre, inventor of daguerreotype process which bears his name, who attempted in 1839 to photograph the moon. Tracking error to guide the telescope during long exposure meant that the photos turned out fuzzy blur. John William Draper, new York University Professor of chemistry, physician and scientific experimenter managed to make the first successful photograph of the moon a year later, on 23 March 1840, having made a 20-minute-long daguerreotype image using a 5 inch 13 cm reflecting telescope.

The sun may have been photographed in 1845 daguerreotype, French physicists Leon Foucault and Hippolyte Fizeau. Unsuccessful attempt to obtain the total Eclipse of the Sun was made by the Italian physicist Giovanni Alessandro Majocchi during an Eclipse of the Sun which occurred in his hometown of Milan, July 8, 1842. Later, he told me about his attempt and the daguerreotype photographs he received in which he wrote:

A few minutes before and after conjunction with the iodized plate in the camera is exposed to light of a thin Crescent moon, and various images were received, but the plate under the action of light of the corona for two minutes in the aggregate do not show the slightest trace of photographic action. No Photo alteration was caused by light crown condenseries lens for two minutes in their entirety, on paper prepared with bromide of silver.

The sun, the solar corona was first successfully captured during the solar Eclipse of 28 July 1851. Dr. August Ludwig Busch, the Director of the königsberg Observatory gave instructions to the local daguerreotypist named Johann Julius Friedrich Berkowski for the image of the Eclipse. Bush himself was not present in Konigsberg now Kaliningrad, Russia, but preferred to observe the Eclipse from nearby Rixhoft. The telescope used by Berkowski was attached to the 6 1 ⁄ 2 inch Konigsberg heliometer 17 cm and an aperture of only 2.4 in 6.1 cm and a focal length of 32 81 cm Starting directly after the beginning of totality, Berkowski exposed a daguerreotype plate for 84 seconds in the focus of the telescope, and on development an image of the corona was obtained. He also exposed a second plate for about 40 to 45 seconds but was spoiled when the sun broke the moon. A more detailed photographic studies of the Sun were made by the British astronomer Warren de La Rue, starting in 1861.

The first photograph of a star was a daguerreotype of the star VEGA by astronomer William Cranch bond and daguerreotype photographer and experimenter John Adams Whipple, on 16 and 17 July 1850 with Harvard College Observatorys 15 inch great refractor. In 1863 English chemist William Allen Miller and English Amateur astronomer William Huggins used the wet plate collodion process to obtain the first ever photographic spectrograms of stars Sirius and Capella. In 1872, the American physician Henry Draper, son of John William Draper, first recorded spectrograms of stars VEGA to show absorption lines.

Astronomical photography did not become a serious research tool until the late 19th century, with the introduction of dry plate photography. It was first used by sir William Huggins and his wife Margaret Lindsay Huggins, in 1876, in their work for the spectra of astronomical objects. In 1880 Henry Draper used the new dry plate process with photographically fixed 11 28 telescopes-refractors the cm, made by Alvan Clark to make a 51 minute exposure of the Orion Nebula, the first photograph of a nebula ever made. A breakthrough in astronomical photography came in 1883, when Amateur astronomer Andrew Ainslie commonly used dry plate process to record several images of the same nebula in exposures up to 60 minutes with a 36 in 91 cm reflecting telescope, which he built in the backyard of his home in Ealing, outside London. These images for the first time showed stars too faint to be seen by the human eye.

The first draft of the Sky photographic astrometry, the Astrographic catalogue and cards-du-Ciel was started in 1887. It was held from 20 observatories around using special photographic telescopes with the same design called normal astrographs, all with an aperture of about 13 in 330 mm and a focal length of 3.4 m 11 feet, designed to create images with a uniform scale on the photographic plate of approximately 60 arcsecs / mm, covering 2° × 2° field of view. The attempt was to accurately map the sky down to 14th magnitude, but it was never completed.

At the beginning of the 20th century, worldwide construction of refracting telescopes and complex large reflecting telescopes specifically designed for photographic images. By mid-century, giant telescopes such as the 200 in telescope 5.1 m Hale telescope 48-in Samuel Oschin 120 cm in the Palomar Observatory were pushing the limits of film photography.

Some progress has been made in the area of photographic emulsions and methods of formation of hypersensitivity of gas, cryogenic cooling, and amplification of light, but in the 1970s, years after the invention of the CCD, photographic plates have been gradually replaced by electronic images in professional and Amateur observatories. CCD is much more light sensitive, do not fall off in sensitivity over long exposures the way film is not "newsimulation", it is possible to record in a much broader spectral range, and simplify storage of information. Now the telescopes used by many configurations of CCD sensors including linear arrays and large mosaics of CCD elements equivalent to 100 million pixels located in the focal plane of telescopes that used 10-14-inch 25 to 36 cm photographic plates.

At the end of the 20th century saw progress in astronomical images take the form of new equipment, the construction of giant multi-mirror and segmented mirror telescopes. It would also see the introduction of space telescopes such as the Hubble space telescope. Operating outside of the atmosphere turbulence, ambient lighting and the vagaries of the weather, allows the space telescope "Hubble" with a mirror diameter of 2.4 meters 94, to record stars down to the 30th magnitude is 100 times dimmer than on the 5-meter Palomar mountain Hale telescope can be recorded in 1949.

                                     

3. Amateur astrophotography. (Любительская астрофотография)

Astrophotography is a popular hobby among photographers and Amateur astronomers. Images of the night sky you can get with the most basic film and digital cameras. For a simple star trails, no additional equipment may be required other than the regular tripods. There is a wide range of commercial equipment is focused on basic and advanced astrophotography. Amateur astronomers and Amateur telescope makers also use homemade equipment and modified devices.

                                     

3.1. Amateur astrophotography. Media. (СМИ)

Images are recorded on many types of media and imaging devices including single-lens reflex cameras, 35 mm film, digital single lens reflex cameras, simple Amateur-level and professional-level commercially manufactured astronomical CCD cameras, video cameras, and even ready Webcams adapted for long-exposure image.

Conventional over-the-counter film has long been used for astrophotography. The exposure of the film in the range from seconds to hours. Commercially available color film is subject to reciprocal failure over long exposures, in which there is sensitivity to light of different wavelengths go at different rates with increasing exposure time, resulting in a color shift in the image. It kompensiruet using the same technique used in professional astronomy to take pictures at different wavelengths, which are then combined to create the right color image. Since the film is much slower than digital gauges, tiny errors in tracking can be corrected without much noticeable effect on the final image. Film astrophotography is becoming less popular because of lower operating costs, greater sensitivity and convenience of digital photography.

Since the late 1990-ies of fans, following the professional observatories in the transition from film to digital CCDs for astronomical imaging. CCDs are more sensitive than film, which gives the opportunity to significantly reduce the time of exposure, and have a linear response to light. Images can be captured in many short exposures to create a lasting impact synthetic. Digital cameras also have minimal or no moving parts and the ability to be controlled remotely via the infrared remote or a computer modem, limit vibration. Simple digital devices such as Webcams can be modified to allow access to the focal plane and even after cutting a few wires on long exposures. Digital video cameras are also used. There are many techniques and pieces of commercially manufactured equipment for attaching digital single reflexDSLR lens cameras and even basic point and shoot cameras to telescopes. Consumer digital cameras suffer from image noise over long exposures, so there are many methods for chamber cooling, including cryogenic cooling. Astronomical equipment companies now offer a range of purpose built astronomical CCD camera complete with hardware and software for processing. A commercially available digital SLR cameras have the ability to take a long exposure time in combination with sequential time-lapse images allows the photographer to create a picture of the night sky.



                                     

3.2. Amateur astrophotography. Post-processing. (Пост-обработка)

Both digital photographs and scanned film images, as a rule, is adjusted in the software image processing for image enhancement in some way. Images can be brightened and manipulated in the computer to adjust color and contrast enhancement. More sophisticated techniques involve capturing multiple images sometimes thousands to mix together in an additive process to sharpen images to overcome the atmospheric seeing, negating tracking issues, identifying faint objects with a poor signal to noise ratio, and filtering out light pollution. Digital camera images may also require additional processing to reduce the image noise from long exposures, including subtracting dark frame” and image processing called stacking or shift-and-add ". There are several commercial and freeware software packages designed for astronomical manipulation of the photographic image.

                                     

3.3. Amateur astrophotography. Equipment. (Оборудование)

Astrophotographic hardware among non-professional astronomers varies widely, since the photographers themselves range from General photographers some form of aesthetically pleasing images for a very serious Amateur astronomers collecting data for scientific research. As a hobby, astrophotography has many challenges that must be overcome that are different from the usual pictures, but from what is normally encountered in professional astronomy.

Since most people live in urban areas, the equipment often needs to be portable, so it can be taken away from the lights of major cities or towns to avoid urban light pollution. City astrophotography can use a special light pollution or narrowband filters, and modern computer technology to reduce ambient urban light in the background of their images. They may also stick to imaging bright targets like the Sun, Moon, and planets. Another method used by Amateurs to avoid light pollution is to set up, or the lease time on remote-controlled telescope on the dark background of the sky. Other challenges include setup and alignment of portable telescopes for accurate tracking, working within the constraints" off the shelf” equipment, endurance test equipment and sometimes manually tracking astronomical objects over long exposures in a wide range of weather conditions.

Some manufacturers modify their products to be used as astrophotography camera such as canons EOS 60da based on the EOS 60D, but with a modified infrared filter and low noise sensor with heightened hydrogen-alpha sensitivity for improved capture of red hydrogen emission nebulae.

There is also a camera specially developed for Amateur astrophotography based on commercially available image sensors. They can also allow the sensor to cool down to reduce thermal noise in long exposures, to provide raw materials imaged and controlled with a computer for automatic image processing. Raw read images allows in the future to better handle image, preserving all the original image data, along with the accumulation of can help in the visualization of weak deep sky objects.

At very low light possibilities, a few specific models of Webcams are popular for solar, lunar and planetary images. Basically, it is a manually focused camera with CCD instead of conventional CMOS. The lenses of these cameras are removed and then these are attached to telescopes to record images, video, or both. In new technologies to make videos of very faint objects and sharp shots stacked together to get a still image of respectable contrast. At Philips, PCVC 740K and SPC 900 are one of the few Webcams love astrophotography. Any smartphone that allows long exposures can be used for this purpose, but some phones have a special mode for astrophotography, which will stitch together multiple exposures.



                                     

3.4. Amateur astrophotography. Setting up the equipment. (Настройка оборудования)

Fixed or tripod

The most basic types of astronomical photographs are made with standard cameras and photographic lenses mounted in a fixed position or on a tripod. Foreground objects or landscapes, sometimes composed in the frame. All objects of the constellations, interesting configurations of planets, meteors and bright comets. The exposure time should be less than one minute to avoid star image become an elongated line due to the rotation of the Earth. Camera focal length lenses valid usually short, as longer lenses will show image trailing in a matter of seconds. Deliberately allowing the stars become elongated lines in exposures lasting several minutes or even hours, called" Star trails”, is an artistic technique is sometimes used.

Tracking mounts

To achieve longer exposures without objects blurry, some form of tracking mount is usually used to compensate for the Earths rotation, including commercial Equatorial mounts and homemade Equatorial devices such as trackers barn door Equatorial platform.

"Piggyback" photography

Piggyback astronomical photography is a method by which the camera / lens mounted on a Equatorial mounted astronomical telescope. The telescope is used as the management area, to keep the field of view centered during the exposure. This allows the camera to use a slower shutter speed and / or longer focal length lens or even be attached to some form of photographic telescope co-axially with the main telescope.

Telescope focal plane photography

In this type of photography the telescope itself is used as the "lens" collecting light for the film or a CCD camera. Although this allows for the magnification and aperture of the telescope to be used, it is one of the most difficult astrophotography methods. This is because of the difficulty in centering and focusing sometimes very dim objects in the narrow field of view, contending with magnified vibration and tracking errors, and the additional costs of equipment There are several different ways cameras with interchangeable lenses for Amateur astronomical telescopes including:

  • Positive projection – a method in which the telescope eyepiece or eyepiece projection, positive lens placed after the focal plane of the telescope objective is used to project a much more magnified image directly on the film or CCD. Since the image is enlarged with a narrow field of view this method is typically used for lunar and planetary photography.
  • Negative projection is a way of positive projection, gives a magnified image. A negative lens, usually a Barlow or a photographic tele-Converter is in the light cone before the focal plane of the telescope objective.
  • Compression – compression uses a positive lens is also called a focal reducer is placed in the converging cone of light to the focal plane of the telescope objective to reduce the overall scale of the image. It is used on very long focal length telescopes, such as Maksutovs and Schmidt–Cassegrains, to obtain a wider field of view.
  • The main focus in this method the image obtained with a telescope falls directly on the film or CCD with no intermediate optics or telescope eyepiece.

When the camera lens is not removed or not removed more common method used is afocal photography, also called afocal projection. In this method, as the camera lens and telescope eyepiece are mounted. When both are focused at infinity the light path between them parallel to afocal, allowing the camera to mainly photograph all that the observer can see. This method works well to capture images of the moon and brighter planets, as well as a narrow field images of stars and nebulae. Afocal photography was common with early 20th century cameras consumer level, as many models had removable lenses. It grew in popularity with the introduction of point and shoot digital camera, as most models also have removable lenses.

                                     

3.5. Amateur astrophotography. Remote Telescope Astrophotography. (Удаленный Телескоп Астрофотография)

With the development of fast Internet in the last part of the 20th century, along with advances in computer controlled telescope mounts and CCD camera remote telescope Astronomy is now a viable means for Amateur astronomers not aligned with major telescope to participate in research and deep sky imaging. This allows the imager to control a telescope a large distance in a dark place. The observers can image telescopes with CCD cameras. Imaging can be performed regardless of the location of the user or the telescopes they wish to use. Digital data collected by the telescope is transmitted and displayed to users via the Internet. An example of a digital remote telescope control for use over the Internet is the Bareket Observatory.

                                     
  • of astrophotography long practiced by astronomers. Afocal setups with film and digital cameras are not the preferred system for astrophotography since
  • camera astrophotography Lovejoy is known among amateur astronomers for identifying modifications to digital cameras needed for astrophotography Such
  • astronomer, best known for his publications and images in amateur astrophotography both in film and CCD. Newton took his first astrophotograph when he
  • observatory Retrieved March 31, 2014. Ken Crawford Capturing the Stars: Astrophotography by the Masters, ed. Robert Gendler, Voyageur Press, 2009, p. 135 Ken
  • known for his pioneering work in astrophotography in particular with cooled and hypered emulsion astrophotography before silver became silicon with
  • Stars, Astrophotography by the Masters IC 1396A. Telegraph.co.uk. Retrieved 2010 - 10 - 13 Elephant s Trunk Nebula in IC1396 Paul Beskeen Astrophotography Retrieved
  • Astronomy portal IRIS is an image processing software for astrophotography IRIS is free for non - commercial usage. Image aligning and stacking, calibration
  • Products already serviced have a black dot inside the tripod socket. An astrophotography variant with a special infrared filter capable of deep red near infrared
  • telescope, a 6 reflector, at his home in Los Angeles. His interest in astrophotography grew in the 1970s and 1980s and been worked as a photographic stringer
  • Alpine Astrovillage AAV is a center for astrophotography and stargazing in the eastern Swiss Alps, high above the valley floor of the Val Mustair in
                                     
  • need for tracking adjustments for exposures beyond a few minutes, as astrophotography demands an extremely high level of precision that these devices typically
  • 2015 - 08 - 18. Media related to NGC 6871 at Wikimedia Commons NGC 6871 at WEBDA NGC 6871 at Bernhard Hubl s Astrophotography NGC 6871 at Astronomy Magazine
  • known for his work as an amateur astronomer, pioneering the field of astrophotography of nebulae. He was a member of the Liverpool Astronomical Society in
  • French amateur astronomer, specializing in astrophotography An engineer by trade, he started astrophotography in 1993 and resorted to CCD cameras to photograph
  • astrographic camera is a telescope designed for the sole purpose of astrophotography Astrographs are mostly used in wide field astronomical surveys of
  • and astrophotographer. He has used CCD cameras since starting out in astrophotography and specializes in images of deep sky objects with very long exposure
  • the two researchers founded the Alpine Astrovillage, a center for astrophotography and stargazing. It is situated in the Eastern Swiss Alps, in the UNESCO
  • and is called Registax. Vandevenne, Pierre 2003 - 04 - 16 Digital Astrophotography Beginner s Guide - Article Retrieved 2013 - 05 - 26. Registax by Cor
  • sheet, altitude charts, sky map and related objects - Deep Sky Objects Browser Little Ghost Nebula amateur astrophotography - Deep Sky Objects Browser
  • Popular applications include photography, videography, and astrophotography In astrophotography these qualities are most desirable when taking pictures


                                     
  • an English amateur astronomer best known for his pioneering work in astrophotography Common was born in Newcastle Upon Tyne on 7 August 1841. His father
  • lunar photographs. Astrophotography Night photography Sunny 16 rule Jerry Lodriguss. A Beginner s Guide to DSLR Astrophotography Jerry Lodriguss. A
  • doctor and amateur astronomer. He is best known today as a pioneer of astrophotography Henry Draper s father, John William Draper, was an accomplished doctor
  • the two researchers founded the Alpine Astrovillage, a center for astrophotography and stargazing. It is situated in the Eastern Swiss Alps, in the UNESCO
  • observation of minor bodies. Chiavenna s activities there include astrophotography software development and observation, during the course of which he
  • with no flash or tripod. Astrophotography - Google updated the Pixel 3a with an improved Night Sight featuring an astrophotography mode Super Res Zoom
  • and the University of Odessa. He did research on astrophysics and astrophotography in multi - year stays at the Observatory of Meudon and at the Astrophysical
  • High quality print outs for sky charts. Ekos is an astrophotography suite, a complete astrophotography solution that can control all INDI devices including
  • equipment, books, and computer software amateur telescope making and astrophotography The articles are intended for the informed lay reader and include
  • application of photography to astronomy. The primary subject of his astrophotography was capturing double stars. The Shternberg Astronomical Institute

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