Strange streaks in darks - put the cap on the camera

[Jerry Barnes]

I was post processing some images from a few nights ago and found some extra "nebulosity" between the Pelican and the North American Nebulae.   I was sure it shouldn't be there and yes, it was definitely surplus.  It took a while to track down and eventually I found it in the darks.  Thinking it must be some light leak, probably from the filter drawer, I re-took darks after wrapping the filter drawer in some old ties.  Still didn't work.

I did wonder if there was some light reflecting off the Bahtinov mask which is built into the cover on the scope (normally covered by the screw on cap on the cap) but I'm not going to worry about it.  After taking the camera off the scope and putting screwing the cap onto the camera (metal cap) the problem was bypassed.

Now if I can just sort out those flats........................