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How to become an astronomy star

Posted on 14 Apr 2009 at 11:58

Admittedly, the effectiveness of these mounts shouldn't be exaggerated. According to the SPA's Robin Scagell, many people buy GoTo telescopes in the belief that "they'll just look through the telescope and everything will be there".

"You still have to put in a fair amount of interest and expertise," he warned. "Even though most GoTo telescopes will give you a tour of the objects in the sky, they still require you to get out there and get your telescope going." Nor should beginners expect to see Hubble-style clouds of space dust and glowing nebulae. "I'm pretty sure that people might have greater expectations of what they can see through a telescope than what you can see, particularly with the smaller ones," Scagell notes.

Shooting stars

The real breakthrough in amateur astronomy, however, has been the pairing of digital imaging with telescopes. Ten years ago, getting decent images of the stars was difficult for two reasons. First, capturing the small quantities of light emitted on film meant long exposures of 90 minutes or more. Second, unless you kept your subject firmly in frame for the whole exposure, manually adjusting the direction of the telescope using a guide star, your final image would be blurred. Today, a typical digital image of the same subject can be captured in several shorter, digital exposures of five to 20 minutes in length, with the different exposures montaged together using specialist - some open-source - processing packages such as Deep Sky Stacker, PixInsight, Nebulosity or Maxim DL. "Now, with the affordability of CCDs, webcams and digital cameras that can take long exposures, motorised mounts to smoothly track the object you're imaging, and the software to process images, some of the pictures that amateurs are taking are truly capable of rivalling some of the professional stuff," argues Astronomy Now's Keith Cooper. "That has been the biggest leap in the last decade."

Note the mention of webcams. Certain cheap webcams, carefully modified, make surprisingly good astro-imaging devices, and have been adopted by the DIY-loving astronomer. They're light enough to be fitted to smaller telescopes, and there's no need to worry about tracking. You simply allow your object to traverse the aperture of your telescope, capturing images at 60 frames per second, then stack and process those images as you would those from a high-end digital SLR. "Webcams have transformed planetary photography and lunar imaging," said Robin Scagell. "I can go down to Tesco and buy a webcam for less than a fiver, and take a better picture with a small telescope than I could have done with a larger telescope ten years ago on film."

Some of the modified webcams have evolved into more expensive but higher performance CCD imaging devices, such as those from Atik or Artemis, although the website www.astronomiser.co.uk still sells more wallet-friendly webcams pre-modified for the purpose.

Astro-photography isn't merely a question of impressive images. For some, astro-imaging has been astronomy's saviour when light pollution is making the practice unviable in most urban areas; the image produced by a CCD will beat anything you can see with your eyes through the telescope. "If it hadn't been for technology, I think astronomy would have declined quite considerably - and the reason is because of the increase in light pollution," Scagell said. "Only recently I saw a picture from a friend, and if I'd seen it 25 years ago I'd have said that it had to be taken from the Arizona desert - but he lives in Edgware!"