Setting Parfocal rings ?

[Roog]

Hi, I seek your experience on a small matter of setting/fixing parfocal rings perpendicular on the  eyepiece/extension tube sleeve?

I have some 2" parfocal rings which I want to use on my 2" extension tube to set the length of extension achieved and from experimenting with them it has occurred to me that it is possible to set these rings slightly off square or not perpendicular to the wall of the tube/optical axis.

Is there a neat way of avoiding this? I can see that I can visually follow the line were the tube meets the next by eye, I just wondered if there was a fool proof way of fixing these square? 

[johninderby]

Just fit the eyepiece or extension into a diag and then tighten the grubscrews on the rings.That way you can see if the ring is square.

Edited December 20, 2021 by johninderby