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Kev,
The most popular CCD at the moment is a camera using the Kodak KAF8300 sensor. That is 8.3 megapixels and is quite sensitive and at 18mm x 13.5mm it gives a reasonable field of view.
There are many manufacturers who use that sensor -
Atik, QHY, Starlight Express, Finger Lakes Instrumentation, SBIG, QSI, Apogee, Moravian even Orion and Celestron.
A lot here use the QHY model. So probably QHY and Atik are the most economical.
Starlight Express would be one of the next cheapest along with SBIG. SBIG has an ST8300 model which is around US$2000.
So it depends on your budget.
The Atik 314 with the icx 285 sensor may be a little small which will make it hard for someone newish to astrophotography as it will magnify all the images like a digital crop. It will make tracking and guiding so much harder.
Unfortunately Astro CCD cameras are quite expensive and there is one shot colour versus mono. Mono requires filters and a filter wheel which adds to the cost but makes better images. One shot colour is a step up from DSLR imaging but processing is very similar. Also no filter wheel and filters are required. So its generally cheaper.
QSI offers a camera with a built in filter wheel and a guider so that is very convenient. Also a range of the smaller sensors like the KAF8300 and the Sony 694, 814 sensors.
Things to evaluate with cameras:
1. The sensor - what is its QE? (quantum efficiency which is what % of photons received does it convert to an electron (signal)). QE of the KAF8300 is about 59%. The Sony icx694 QE is 77%. These are both high numbers.
2. Read noise (this is the amount of noise generated by the action of reading the signal off of the CCD measured in numbers of electrons).
3 electrons is extremely low, 9 is common).
3. Size of the sensor. Large CCDs cost a lot of money and require optics that can handle such a large CCD. Smaller sensors are easier on the optics but have a narrower field of view which magnifies the tracking errors. So a happy medium is needed. The Sony ICX694 and the Kodak KAF8300 are 2 of the popular sized sensors at the moment.
4. How many degrees below ambient air temperature does the camera cool? The cooler the better.
5. Download times - how long does it take the camera to download an image.
6. Other features - SBIG have some self guiding cameras with a 2nd sensor in a filter wheel for guiding, QSI has a built in filter wheel and guider option etc.
7. Cost. KAF 8300 cameras from different manufacturers vary from about $2000 to $6000.
What sort of budget do you have?
Greg.
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