Now what???

[northcanadian]

Hi all:

Thought I had this ASI 120mm sensor glass cover cleaned  prior to last imaging session.  I blew it off then cleaned with isopropyl alcohol, blew it off again...didn't see any dark spots when I ran the camera in low light thru the rgb filters.  Last imaging session there they were again. Today cleaned sensor a few times, ran camera in low light and didn't see any motes. However when I put in a 2x barlow and did the same...there they were again! Cleaned barlow, cleaned filters, but still there.  what am I doing wrong???  Appreciate any help on this (as usual)

This is through the L filter and 2x barlow

Cheers

Roger

[Demonperformer]

I suspect it is virtually impossible to make all your filters/lenses clear of all these imperfections. It is these artifacts that your flat frames will get rid of from your final image (I think).

[PeterCPC]

I had a "blob" that I could not locate anywhere in the image train - my conclusion was that it was the laptop screen. It did not show on the final image.

Peter