What equipment is invoved in our astrophotography?
70cm RC Landessternwarte Heidelberg
The Landessternwarte Heidelberg ('Heidelberg State Observatory') was founded in 1898 on the Königsstuhl mountain. Lead by Max Wolf, a pioneer in using astrophotography for scientific research, it contributed major scientific results in the fields of galactic nebulae and the discovery of asteroids. Today's research is focussed on developing instrumentation, the detection of exoplanets and exploration of the high redshift universe. Despite that the observations nowadays are conducted in coorperations with the ESO and LBT Observatory, there are still multiple professional, scientific capable telescopes in use today. It's tasks are follow-up spectroscopic confirmation of exoplanets and scientific training for astronomy students of the Heidelberg University. Members of our astrophotography team are working at the observatories scientific research and are granted access to the telescopes on special occasions, opening a great opportunity of using instrumentation not commonly available to amateur astronomers. Furthermore the group can take advantage of the observing conditions at the observatory site fro projects with our own amateur equipment, escaping a small fraction of light pollution and local seeing of the Rhein-Neckar metropolitain area.
Our main observatory telescope is the 700/5600mm Ritchey-Chrétien Astrograph, constructed in the late 70s for Quasar Monitoring. Together with the 'Waltz-Telescope', it is the largest telescope at the observatory. It features the follwing specifications and instrumets:
We own a large collection of mid-range amateur telescopes ourselves that are spefically designed for astrophotography under our common observing conditions.
The Takahashi Epsilon is a hyperboloid newtonian astrograph. Its design is derived from the original design of newtonian reflectors, but highly optimized for fast widefield astrophotography. It has a focal length of 430mm and hence a f-ratio of f/3.3 while being able to cover imaging sensors up to the full frame format and excels at deep imaging of galactic nebulae.
The Hypergraph 6 is of the same optical design as the Takahashi Epsilon. It features a slightly larger hyperboloidal primary mirror of 150mm Diameter and a focal ratio of f/2.8, yielding a focal length of 420mm. The very similar specifications opens up the possibility of parallel imaging when fitting cameras with a comparable FOV and pixel size.
This telescope is a classical Newtonian telescope, using a 200mm paraboloidal primary and flat secondary mirror. It can be used with different coma correctors, yielding focal lengths of 570mm or 800mm. It is used for moderately large nebulae and larger galaxies.
With an aperture of 254mm, the Skywatcher 10" Newton is the largest telescope in our collection and maxes out the capabilities of the available mounts. It has a focal ratio of f/4 and is primarily used for detailed imaging of nebulae and moderately large galaxies or the specialized short eposure technique. We have 2 specimen of this telescope at different observing locations.
The 8" (or 208mm) Ritchey-Chrétien Astrograph has a focal length of 1600mm and excels at detailed, high resolution imaging of small galaxies in narrow field of view. It is a purely reflecting optical design and is therefore very well suited for scientific observations.
The Skywatcher Skymax 180mm Makutsov-Cassegrain telescope has a focal ratio of f/15 and is therefore highly specialized for planetary and lunar imaging, providing high contrast and field sharpness. It used ocasionally for these observations in contention with the 10" Newtonians.
Equatorial Mounts are essential for any form of astrophotography, as they compensate for the earth's rotation and enable long exposures to capture astronomical objects.
This tiny equatorial mount is designed to be used with camera lenses for widefield images of our galaxy. We use it with a 50mm Sigma Art f/1.2 lens and Canon DSLRs, as a dedicated secondary or travel setup.
Astronomical Cameras and Filters
In order to capture the night sky in all its colorful beauty we use cameras of different design and functionality.
This camera has been the workhorse and essential piece of equipment for the majority of our projects. It has a monochrome CCD sensor, being able to capture objects at full resolution without a typical RGB-Bayer matrix. To create color images, it is used with different filters, capturing each color channel at a time. This enables it to also use narrowband filters, that isolate the structure of emission nebulae and ignore most light pollution. To reduce noise the camera can be cooled up to -50°C under ambient temperature.
The monochrome Atik ONE 6.0 CCD camera uses one of the best performing CCD chips available. This chip has a very high sensitivity and low noise profile but comparable small size, letting the camera excel at imaging faint and small targets, such as distant galaxies or old planetary nebulae. It can also be fitted with RGB or Narrowband filter utilizing its internal filter wheel.
When starting with astronomy, one wants to use an intuitive Camera that might be already available from regular daylight photography. A DSLR perfectly serves this purpose, being very cost efficient and also creating images easy to process. The Canon 600Da has a reasonably good noise profile and resolution for astrophotography at a low price and is therefore widely common under beginners. When removing the internal IR-cut filter it can be used to capture emission nebulae. We own two of these cameras as remnants of or first steps in astrophotography and currently use them for widefield photography and timelapses.
This color CMOS camera is paired with one of the 10" Newtonians and serves as an allround instrument for this telescope. It is mainly used for demanding applications where the use of a monochrome CCD is not required or the easier image processing of this camera's data preferred.
Taking images of planets or the moon poses a lot different requirements on the cameras. Modern CMOS sensors with small and sensitive chips or very specialized CCDs (such as the DMK cameras) excel with their low read-noise and high framerate. Videos are taken and their individual frames stacked for final images. Guiding the telescope is also perfectly performed by these cameras. Therefore we own multiple exemplars:
Filters serve multiple purpose in astrophotography. They are used to create color images from monochrome cameras, isolating emission lines of specific chemical elements in nebulae or blocking light pollution. We mostly use Astronomik filters, since they have a good quality at a very reasonable price. Used filters are:
There is of course a lot more equipment involved in our observations. Such as Laptops, Filterwheels, Adapters, Dew Heaters, Power Supplies and Eyepieces. They are essential to every project but listing everything would exceed the course of this webpage.