Re: aligning secondary

Chris Knight (cknight@awinc.com)
Sat, 22 Jul 95 00:32 PDT

>You may need to reposition your secondary. This is accomplished by
>stretching a string the length of the tube, carefully centered at both
>ends, threaded through the spider. After this centering is achieved, you
>can then use your film canister technique to move the secondary
>longtitudinally until centering is achieved.
>
>You'll probably want to check the centering of the primary in its cell as well.
>
>--
>Steve Strickland
>Lensnut@tpoint.net

Hi Steve, Both the secondary and the primary are centered in the tube to within .050 of the radius of the tube. The problem is longitudinally. I have heard of putting a dot with a permanent marker in the EXACT centre of the secondary, but I don't wish to do this in case there is any image degradation or damage to the mirror coatings.

Chris