CCD vs Film? Lots of time vs no patience? Alright, this is your place to discuss all the astrophotography what's and what's not. You can discuss about techniques, accessories, cameras, whatever....just make sure you also post some nice photos here too!
If dust on the sensor, then it will not change position on the photo. If you have a chance to look at the original photos, it changes position. Also, the green colour come from the multicoat of the lens