I’ve just purchased a used GSO (?) CF RC-8.
I’ve heard a lot about the difficulty with collimating them so I was very wary of my first dive in.
It turns out my secondary mirror does not have a centre sticker so all the collimation videos I found were a bit wrong for my use so I’ve had to adapt and make up my own method of collimation.
It seems fairly simple, so I would like some other eyes on it to give me an opinion on what seems good or bad.
Prep. Remove all the extenders and mount the focuser as close as possible to the mirror. (I have a moonlight focuser with built in tilt adjuster, and do not have a tilt ring)
Step 1. Adjust the primary.
Normally this is done with a laser or Cheshire aligning with the hole in the secondary sticker. Since this is missing, I’ve used a TSRCKOLLI to get an even circle of light around the baffles by adjusting the primary push pull bolts.
Step 2. Adjust the secondary.
Easy to adjust the big hex key bolts on the secondary so that out of focus stars were round.
Step 3. Validate collimation
Use a tri-Bahtinov mask to make sure everything looks cantered and even. See pic below.
Step 4. How to check and align the focuser.
Not sure on this one, don’t know if it even needs to be done. Thoughts?
