Quote:
Originally Posted by coldspace
This is what we are looking for, a possible solution to a big problem,
and helping a fellow astro mate out as well.
Good on you, for even if you can't help directly a little direction for Peter can go along way  .
Let us all know Peter how you go and who helps you out.
Matt. |
Thank you Matt and Peter in particular. I will email Peter off-site as he has suggested but in case there is someone else out there who now, or later has a similar problem and needs to recollimate the primary and secondary on a GSO RC, I note that I did find a discussion in CN where the technique of collimation was discussed. It was in the context of Astro-Tech scopes which are, effectively, GSO. The suggestion that was offerd there was to use a Cheshire without crosshairs or a pinhole in a film canister to do a visual alignment of the reflection of the baffle tube in the secondary by adjusting the push-pull screws on the back of the scope and then, using a laser collimator tha projects a hologram to cast the shadow of the secondary onto a flat surface against a grid pattern so that the mechanical alignment of the secondary can be confirmed - i.e. making sure it is algned with the optical axis; then, using a dot-point laser collimator into the eyepiece holder, move the secondary mirror until the return dot was centrally placed on it - the laser folded back on itself.
An interesting phenomenon discussed there without a solution and that I also encountered was that although there is no physical connection between the secondary and the primary, when you adjust the secondary, the initial line-up of the baffle tube has shifted and you have to loop back to step 1 again. Not sure why this is so, but after half a dozen attempts at this today I had to pronounce myself knackered and ready for something else.
I will revisit this thread with a more detailed description if a successful technique emerges out of this unfortunate experience.
Peter