[ribuck (Richard)]

Hi All,

I'm looking for some help with RC collimation and i posted on a forum in the uk and someone recommended posting my question on here as they believed there are some RC experts who know these scope inside an out.

So i'm glad i came as it looks like a great forum, which i'll look forward to using in the future.

Well onto my issues...

I bought a second hand 8" RC and i'm trying to collimate the scope with a Takahashi collimating scope, but now matter how i try i cannot get the the secondary donut reflection to align using the secondary screws. The only way i can seem to get it to align is by adjusting the primary, which is no good as it then throws the primary way out.

I start by using a laser and the tilt adapter plate to ensure that my focuser is properly aligned.......check.....

Now i move onto the secondary. So i'm looking into the Tak Collimation scope and i see the black dot and i can get it central adjusting the secondary, but within the black dot, there is a smaller faint white ring, which i'm assuming is the secondary donut reflection, and now matter how hard i try i cannot get the faint white circle concentric inside the black spot using the secondary adjustment screws.

If i adjust the primary screws, i am able to get the faint white circle in the centre of the small black dot, but this then throws out primary out of whack.

Could this be a mechanical issue with the scope itself or am i just misunderstanding the collimation process ?

i'll try and take some photos later today, which might help explain a bit better.

Many thanks,
Rich.