Hello, Here is a 80mm refractor wide field of some Virgo galaxies.
Notice the blob in the middle.
I took darks when I did the lights. The next day I did flat frames and flat darks using a light box with the camera,scope etc not having been changed around except to park the scope and cover it.
My first set of flats had different dust bunnies on and when I went back to check there was a spot of dust on the light box screen which was obviously not calibrated with the darks and lights.
So I cleaned it all up and re-shot my flats and dark flats.
I used Exfo's light box at 0.5sec at 100 iso with the same set up as my lights i.e home modded canon, CLS filter, scope , light box.
I then turned the light box off and noticed at that exposure is was very dark so I did my flat darks like that.
I still have a dust bunny or something in the centre of the frame.
?Help
Graham