Quote:
Originally Posted by TrevorW
OK really need to know how to get those perfect smooth star images is it better to take fewer longer exposures with a CMOS camera than many shorter exposures to improve signal to noise ratio etc and are there any particular steps needed post processing to improve star images I have Pixinsight LE and PS CS2, CS3 and CS6
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I might state the obvious but the more I image the more I come to the realisation that if the stars are good in your data then everything else falls into place and it gets a lot easier. I now treat them like the canary in the coal mine. So this is my experience.
If you take shorter exposures your star shapes might differ in your subs based on seeing, your guiding and other factors but they will look sharper.
If you expose for longer subs then all these will average out and you might get more bloated stars but they will be very likely rounder. If they aren't then you need to pay attention to field rotation (polar alignment), drift (balance or backlash or flexure) that will come in longer subs.
With longer exposures you need to also pay attention to your star profiles. Based on the well depth of your camera. So you don't burn anything.
Once you have all of the above sorted out the rest is a breeze. You need to find a good non saturated star to get a valid PSF and start sharpening your picture as a whole field with a program that uses correct algorithms for deconvolution and noise reduction on linear files. Not selectively. From there on you can post process in any software for colours, saturation, cropping, orientation, levels, etc...