I've noticed some blue blotches on my pics and am wondering what they are. Using an 80mm ES80 APO with a modded Nikon D5100, a ES field flattener and Orion imaging LPF. They've been present in my B33/Flame, M42, and M45 at least. I thought there was just three but when I looked at my M45 from last night there seemed to be a whole lot more.
These were stacked in DSS, adjustments *applied* just so I could bring out what I was talking about. There are some dark spots, too, probably just dust. But the blotches - just dirt? Pin holes in the filter? Something else? Thanks.
Just off M42: