CCD Astronomical Imaging Using dedicated cooled camerasDavid Ratledge |
IntroductionThe arrival of CCD imaging cameras has revolutionised astronomical imaging for the amateur and professional astronomer. The quality, range and power of equipment available to the amateur imager today is mind blowing. Unlike consumer cameras, the cost of dedicated cooled CCD cameras has remained high - they are not mass produced devices so will probably remain expensive. These cameras from specialist manufacturers range form around £1500 to £10,000 and more. The exception has been Starlight Xpress with cameras from £500, although with physically small chips at the lower prices. Their purchase is therefore a serious decision and with the advent of cheap digital SLRs one to be taken only when the imaging bug bites deep! They are however, unmatched if the target is faint deep-sky objects where their very high quantum efficiency makes them the only serious option. |
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FLI Macam CCD camera |
Cameras Hardly things of beauty but their performance is awesome - very few photons escape! I have used cameras from SBIG, HiSIS, Apogee and FLI. They are probably all very similar (they feature mostly the same chips after all) and typically cost from £2000 upwards. Don't expect megapixels at the lower price points! However, even the smallest will be big enough for nearly all galaxies and planetary nebulae. One thing to be aware of is they are vacuum sealed cameras and will eventually need re-purging. It seems to be a matter of luck how long they will last before they need to re-purged. However, recently Apogee have introduced cameras with a life time guarantee against the camera seal failing. |
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One much overlooked aspect of dedicated CCD cameras is their near infra-red ability. In fact almost 50% of their sensitivity can be in the infra-red. Using no filters or ones that pass IR can double the sensitivity of the camera. You will need optics that can focus the IR though - RC telescope are ideal for this having only relecting surfaces.
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 Crab Nebula (click for larger image) |
Software
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I mentioned elsewhere that you would spend more time processing than imaging. In Britain that is not difficult but it is true generally. There are several software packages available from freeware to expensive-ware! I use both freeware (IRIS) and Maxim.
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For starters I would recommend IRIS. It is written by Chritian Buil who invented amateur CCD imaging. It is difficult to learn and requires much reading but it does virtually everything. It is constantly developing and if it doesn't do someting today I bet it will tomorrow! It has recently been expanded to cover DSLRs and solar imaging!
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The Ring Nebula (click for larger image)
NGC7331 (click for larger image) |
Iris
Imaging Books |
I couldn't not mention books. Whilst reading webpages is great for a quick overview, nothing can compare to a good book! Fortunately there are two good ones I can recommend which feature leading astro-imagers from around the world:- The Art & Science of CCD Astronomy - available from Sky & Telescope and quite often secondhand. Still the best introduction and the first imaging book with a colour section!
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Digital Astrophotography - NEW and covers Webcams, Afocal consumer cameras, DSLRs, Planetary imaging, Deep-sky imaging, Spectroscopy and Supernova discovery. This is a full colour book - again a first !
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