FS-102 NSV Collimation

I just acquired an FS-102 NSV, and looking at a in focus star at 250X, the diffraction ring is not the same brightness all the way around. Does this refractor have any collimation adjustments? I can't find any. Am I being too picky? It gives very sharp views.

Thanks!
Alan

Are you using a diagonal? If so, try it straight through and then inspect the diffraction pattern.

If it is the same straight through, please contact me and we will help you.

Art Ciampi

What you are describing is a slight amount of coma,
and it will have almost no effect on image quality.
A 50% variation in the brightness of the first
diffraction ring corresponds to about 1/20 wave P-V
error and 0.5% reduction in Strehl ratio (i.e.
from 1.000 to 0.995). That said, of course it
is nice to have "perfect" optics if you can get it.