Hey Leon, don't you hate it when you get all those views and no reply?
As far as I have read in so many tutorials, just a white T-shirt stretched smooth over your objective and evenly lit should do the trick.
I am thinking of using the t-shirt in conjunction with a 100 watt light globe shining on it from a couple of feet away.
I haven't used flats in any of my astrophotos yet, so I don't know what kind of improvement it will make yet.
Hope this some help mate.
Cheers.
