Quote:
Originally Posted by Crushellon
I don't understand the short exposures though
|
To get the best SNR in the shortest total time you need to take subs long enough that read noise is swamped by shot noise from the detected signal. If you have a sensor with low read noise, e.g. ASI1600, then you can take shorter subs and still be in this magical goldilocks zone. With a KAF-8300 you'll need to take longer subs which requires better guiding, results in more data loss if a cloud wanders through your FOV, and probably gives you detail that's a little less sharp. On the plus side, you'll need less CPU grunt to calibrate, register and integrate the data.
You can get good results with CMOS or with CCD. It's a matter of using either sensor to best advantage.
If terms like read noise, shot noise and quantum efficiency mean nothing to you, then you really should do a little reading. The Handbook of Astro Image Processing book by Berry and Burnell is very good or try the signal to noise articles by Craig Stark:
http://www.stark-labs.com/craig/articles/articles.html
You'll hear a lot of opinions about this stuff but many of them are uninformed. It's a good idea to learn a little. The maths behind this stuff isn't terribly difficult and intuition will often lead you astray.
PS. Ray (Shiraz) is one of the folks that does understand the maths. You can generally believe what he says
Cheers,
Rick.