What the..........?

[martin_h]

Any ideas what's causing this? I thought it might be the flats but I used the same set on a shoot earlier in the evening and its ok, same darks, and bias too. If it was an OSC I would say bayeur pattern but its a mono cam..

[Shibby]

Hmm, some sort of interference pattern. I also notice that there are dark patches around the galaxies... I'm no expert, but have you accidentally included your light subs in your flat stack?

[martin_h]

Nope, its the same Master Flat as I used on another stack earlier in the evening..I tried making a new master in Nebulosity and stacking them in there, no pattern but the flat didn't do anything either!! all dust bunnies showing, whereas in the above shot its removed the bunnies but left a pattern...........No worries I've deleted the lot - flats and lights and will re-shoot again, oneday.......only 4 hours wasted!