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Daniel,
There have been many comparisons done between various stacking software and Deep Sky Stacker ranks fairly high ( refer Dylan O’Donnell Star stuff channel on Stacking software ) plus it’s free . I’ve used it for nearly 4 years and has never produced a bad stacked image
In regards to Noise , remember DSLR’s are uncooled and the electronics controlling the sensor can get up to 35degC or more in summer and only as low as only 15degC in Winter. DSLR’s were never originally designed for long exposure Astrophotography but we have through trial and error learned how to use them even with their deficiencies. The thermal noise or dark current created by a DSLR cannot be reduced inside the camera unless you cool the camera down to a temperature which off sets the thermal rise during long exposures
Below is some technical data on Noise and SNR Etc....
Noise and SNR
Photons are the fundamental particles of light
Signal is photons from the DSO together with nuisance Skyglow and Dark current ( noise )
Noise comprises of Read noise and Shot noise
Quality of images are dependent on the Signal to Noise ratio expressed as
SNR = Signal / Noise
Signal is made up of photons directly from your image target
Noise is target signal + Skyglow signal + Dark signal + Read noise square root
“Skyglow” is basically a build up of luminance in the night sky caused by natural and human sources ( light pollution, reflected light off the moon , star light etc.. )
“Dark current” ( Dark Noise ) is a thermal signal produced by the cameras electronics which subtracts the good signal ( photons ) The higher the temperature of the cameras sensor the higher the thermal signal the higher the dark current or dark noise
“Read noise” is the noise produced by your cameras sensor electronics. A lower read noise has the ability to pick up weaker signals and differences in signal levels
“Shot noise” is the fluctuations in the number of photons detected by the sensor which includes both photons from your object and skyglow. This variation in the number of good and bad photons from each exposure reduces your SNR
Ways to increase Signal
Stack more images ( more Target Signal )
Longer exposures
Lower f Ratio ( more photons per pixel for same time exposure )Eg: 8” f6 newt vs 4” f4 newt using same camera
25% less photons are captured by the 4” scope but 3 times the photons hit each pixel on the sensor
Quantum Efficiency ( QE ) of Camera ( higher the better ) Low is around 40% and high is around 80%
Cool your sensor
Use filters in urban areas
Ways to reduce Noise
Stacking ( increases signal )
Dark frames ( removes thermal signal eg hot pixels etc.. )
Dithering ( removes fixed pattern noise or dark current noise )
Hope the above is helpful
Cheers
Martin
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