[pvelez (Pete)]

I've been wrestling with collimation on my RC8. I had used CCD Inspector and determined I had an error of about 10 arcseconds - huge.

So I did what any of us would do - I started fiddling. Of course I stuffed it up

I bought a Tak collimation scope - still no improvement.

I decided that the primary was out and - you guessed it - I fiddled with that too.

The result - not pretty.

Funnily enough, the Tak scope says its quite close - though perhaps the centre spot on my RC8 is not centred.

Anyway, here is the patient - I'm interested in the diagnosis from the assembled doctors. I took an image of Centaurus A - 300 seconds in L binned x 2 guided. The guiding chart looked quite good.

I ran the image through CCDIP - the data is in the attached. Collimation out by 10.6" with a tilt of 9% and curvature of 19%. That all said, the viewer is still a satisfying indigo.

Then I've given you the image so you can see it in all its ugly glory.

Next I have a close up of stars in the four corners of the image - all are eggy but not to the same extent. I've presented them in order moving clockwise from the top left. The bottom right corner seems most round

So - my question. Is my issue solely miscollimation? Or is my camera/focuser/rotator not orthogonal? Or is there something else weird going on.

I have my Medicare card handy - just waiting for the doctor's report...

Pete