Collimating with an adjustable focuser....?

[daz]

Quick question..

My 12" newt has a collimatable focuser, so should I collimate the main mirror first (stars in the centre well collimated) and then do the focuser (stars on the edges)?

Or is there another recommendation?

Ta

[Paulus]

Hi Daz,

Out of interest, what do you mean by a collimating focuser?

I thought that the better focuser's allowed you to ensure they were lined up correctly with the tube, with grub screw adjusters (like the mirrors). Once you were exactly in line with the focal plane, all you needed to do was do the collimation of both mirrors & check with a star test.

The new focuser I'm fitting is bang on the centre spot 180 deg opposite focuser, using a laser, after a bit if adjusting & checking the laser stayed on point through 360 deg rotation in focuser. So all I should have to do is put the secondary & primary back & collimate, I think!

A picture may be of help if I'm totally off track as I asked in first sentence.

Best regards,

Paul

[daz]

Hi Paul

That's exactly what I have!! I couldn't see how adjusting the focuser AND the mirror would give you good colimation, but your explanation makes perfect sense!!!

It's been so long since I used a newtonian in anger, I'm having to re-learn stuff again! Good fun