I think the pinholes are in the front surface mirror coating. That is why you can see them from behind with a strong light under the mirror.
They can be seen in a five minute exposure as tiny dots but not in the refractor sub .Both cropped down to 1/5 width around 1000x700
They are partly eliminated in stacking but not completely as shown in the first image
Quote:
Originally Posted by AstroJunk
Those pin-holes shouldn't degrade your image and may well have been there since new. In the unlikely event that they get worse by the next time you clean it, then you can consider a recoat. It's the front surface that matters most  |