IT specialist on vacation: a little practice of amateur astrophotography

Having seen the previous post “IT Leader on Vacation: Gadgets for a Telescope” , I decided to reveal a little the topic of astrophotography using a telescope and SLR cameras. I am an absolute lover in this matter, but, I believe, my modest experience can be interesting.

The beginning of the way

I revived my interest in astronomy about 9-10 years ago, when affordable telescopes from Synta and Celestron began to appear on store shelves. The first telescope for me was the Synta Skywatcher 70/900 refractor on the equatorial mount EQ2 with a right ascension motor. Having glanced a little at the Moscow night sky from the window of the apartment and experienced absolutely childish delight at the observation of Jupiter and its satellites, it was decided to capture all this. I didn’t like the idea of ​​shooting on a soap dish, putting it on the eyepiece, and I moved towards shooting in the direct focus of the telescope - that is, when the camera is installed instead of the eyepiece. There were few camera options for less or less high-quality planetary shooting at that time - Meade LPI, Celestron NexImage and Philips webcam. The cost of the camera from Meade was significantly higher than the last two and, as a result, I took a camera from Celestron. Unlike Philips, it did not have to be redone for mounting on a standard eyepiece assembly of an amateur telescope (1.25 ”).

The process of planetary shooting is quite simple - a video was recorded, which was then processed in the Registax program.

Further development of events was standard for a novice astronomy lover - I wanted a bigger telescope. As a result, on the DR, I gave myself an 8 ”(200mm) Celestron C8-N Newton reflector on an equatorial mount CG-5 with motors on both axes.

Main caliber

Based on the characteristics (the diameter of the main mirror is 200 mm and the focal length is 1000 mm), the main focus of the C8-N is deep space objects (the so-called “deep sky”). On a webcam, which, in fact, is Celestron NexImage, it’s difficult to shoot deepbox. Here, slow shutter speeds and a large matrix are already needed. At that time, I already had at my disposal the first affordable Canon EOS 300D digital SLR camera. The only thing left was to buy an adapter ring from a Canon EOS mount to a T thread. Barlow lens with a T-adapter was purchased immediately with a telescope (the lens itself can be twisted). The shooting process looked like this - the subject was located, the eyepiece was removed and a camera was inserted in its place. Focusing was carried out through the camera viewfinder, the shutter was released from the remote control, shutter speed was controlled manually (bulb mode). Thus, I was able to shoot frames with shutter speeds up to 1 minute. At slower shutter speeds, the picture was not spoiled by the ideal tracking of the mount with the mount, the polar axis of the mount not always well set and the weight of all the equipment for this mount.

Example of shooting in direct focus:

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Comet Schwassmann-Wachmann 73P component B. Survey 13.05.2006. Single shot. Canon EOS 300D in direct focus of the Celestron C8-N telescope. ISO 400. Exposure time 30 sec. Without guiding.

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The star cluster M13 in the constellation Hercules.
Shot on a Canon EOS 300D + 2x barlow in the direct focus of the Celestron C8-N telescope. Single shot. ISO 400, shutter speed - 58 sec. Without guiding.


Also, on occasion, I replaced the Celestron NexImage planetary camera with Meade LPI. The Meade camera has one slight advantage over Celestron - the complete Meade Autostar software. The program on the fly adds the frames received from the camera and you can observe the quality of the resulting final image in real time.

Examples of shooting on Meade LPI in direct focus:

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Saturn.
Taken with a Meade LPI + 2x barlow in the direct focus of the Celestron C8-N telescope. The sum of ~ 120 frames from ~ 800


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Jupiter.
Taken with a Meade LPI + 2x barlow in the direct focus of the Celestron C8-N telescope. The amount of ~ 200 frames from ~ 1000


As you know, the appetite comes with eating. It was decided to replace the mount with a more load-lifting and computer-guided Synta EQ-6 SynScan. At the same time, I purchased a small telescope for guiding (Deepsky 80/400 refractor), guiding the QHY-5 black-and-white camera, and made a platform for installing two telescopes on one mount. I think that from this moment it is worth describing the shooting process in more detail:

Guiding allows you to compensate for most of the standard problems of mechanics and electronics mounts. In a simple case, a guided mount requires a mount with the ability to connect to a computer, two telescopes and two cameras. A camera for shooting is mounted on the main telescope and a second small guide telescope with a camera is installed in parallel with it. The mount and guiding camera are connected to the computer. After that, we aim at the subject, find the brightest star in the field of view through the guide telescope and set up tracking of this star in a special program (Guidemaster, PHDGuide, etc.). As a result, the program will track the displacement of this star and send commands to the mount that correct the inaccuracy of the polar axis settings and the operation of the mount motors.

An example of shooting the galaxy M51 "Whirlpool":

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Shot with a Canon EOS 30D in direct focus of the Celestron C8-N telescope mounted on an EQ-6 SynScan. Single shot. ISO 400, shutter speed - 508 sec. With guiding.

Today I settled on the following photo kit:
Celestron C8-N telescope, Celestron CG-5 Advanced GT mount, DeepSky DT80 / 400 guiding telescope QHY5
camera guide, Meade LPI lunar planet camera, Canon EOS 500D camera

PS

There are other ways to shoot deep-sky objects. For example, shooting using specialized cameras such as SBIG, FLI, etc. with filter wheels and shooting time for one subject up to several nights. But, in my opinion, this is not amateur, but professional shooting. And to unlock the potential of such cameras, you need completely different equipment, not comparable in price and quality with affordable amateur telescopes.
And, in conclusion, I should note that, despite the efforts of our Chinese friends and the general development of technology, astrophoto still remains a very expensive hobby.

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