[Astroman (Andrew Wall)]

Hi all,

I am slowly going through my 8" f4 newt, I bought from Bintel back in 2013. I have always had problems with the stars and sometimes I thought I had fixed the problem, but it may have just been seeing, masking the problem. I am not sure. I have collimated this scope more times than I would like to remember trying to solve this little issue I have. Using a Cheshire, sight tube and also went out and bought a cats-eye collimation centre spot and borrowed the collimation tools to get it right. I hope someone on here has seen similar and have a fix for me, because I am slowly losing my mind over it.

The problem is these two blobs that appear on the right hand side of the stars. I was thinking it may have been pressure on the primary, but I have loosened everything off and the mirror is quite free to move around but not so much to wobble about. I have even rotated the mirror in the cell but the blobs remain in the same spot. I removed the front ring that supports the OTA tube, just in case it was that. I have ran a scalpel around the secondary mirror plastic holder trying to remove it, but couldn't, it's stuck quite firm, I didn't want to be too heavy handed with it. I also blackened the edge of the primary mirror.

I am not sure what else to do. I was going to cut a couple of notched in the secondary mirror plastic holder, to remove any strain that may be on the mirror (saw this done on another website) I was also going to reduce the size of the three primary mirror clips, to see if that helps.

I am at a loss of what else it could be. Has anyone seen this sort of star image before?

The image is a single 5sec sub at iso800 of M7 taken in twilight. Canon 1100D, MPCC #1 Coma corrector. 8" f/4 GSO newtonian.

Forgot to add that the Diffraction spikes were put there by me in processing, to visually represent where the actual spikes are on the stars since they didn't show up too well.