SUNSET: 
Imaging Foundations with Richard Wright
Astrophotography: Stacking Up Your Signal
The secret to stacking images in astrophotography is increasing signal rather than just increasing the number of exposures.
Imaging Foundations with Richard Wright
An Astrophotographer's Gentle Introduction to Noise
You don't need a PhD to understand noise in astronomical images — here's an introduction to the various sources of noise in astrophotography and how to combat them.