Quote:
|
Originally Posted by barees63
The other instructions I've read (including the Catseye collimation tool instructions) say that I should tilt the secondary to line up the primary image (and center the center-spot under the crosshair of the sight tube) and just only adjust the Primary while using the cheshire to line up the center spot, but when I start tilting the secondary it now appears off center with regard to the red background paper..
So, what should I try next?  |
I had similar experiences with mine until I discovered that my spider was off centre, ie the secondary was offset sideways and not in the centre of the tube. I had to place a washer under the spider retaining nut on the outside of the tube to get mine centred.
Step 1: Get the secondary centred under the focuser.
Step 2: Adjust secondary tilt so that ALL of the primary is visible and centred in the secondary viewing through the site tube. Your laser can help here by aiming the dot at the centre of the primary. Rotate the laser in the focuser to check how the dots tracks on the primary, this will show how accurate your laser is. The laser will ensure that the optical axis are aligned. Go back to the site tube and check again the mechanical alignment. Any error here will only effect the shape of the fully illuminated field and a small error can be lived with.
Step 3: Adjust primary mirror to get its centre spot lined up with the cheshire.
Getting the secondary lined up is the most time consuming part but you wont need to do it again unless you pull it apart for cleaning etc.
Take your time and keep the screws loose until close to being aligned then nip them up carefully. The secondary holder is made of plastic and can be damaged easily by overtightening, not to mention that the screws can grind a pit in the plastic, making small adjustments difficult as the screws will want to fall into these pits.