Andrew's Collimating Ep.

[cristian abarca]

I made a sight tube out of copper pipe. The type plumbers use and it fits very tightly in the 1.25 inch focuser. The only problem is that I made mine too long so it's too heavy for the focuser. I will cut it soon. I am in the process of collimating with the Andrews Cheshire and it seems to work OK, but I do think that it is too short. There's a website by Nils olif carlson and he gives a formula to how long your sight tube should be, according to the focal length of your scope. Even after doing all this I'm stil not 100% satisfied with my collimation.

Regards Cristian

[asimov (John)]

The one & only thing I can't work out is the need for secondary off-set AWAY slightly from the focuser. With my tube being slightly "egg" shaped, I have no way of working it out.

I understand the need for off-set towards the primary btw.