Re: ATM Collimation, the Truth?

[Carl Brennan <carl@pader-online.de>]

At 22:27 30.05.1997 -0600, Steve Bell wrote:

snip ..

>For consistency of technique, I'd usually start outside of focus, and
>look to see if the central diffraction hole made by the diagonal was
>concentric with the expanded disk. It would almost always be off enough
>for me to have to use the primary mirror cell's collimation bolts to
>tilt the primary so that it became concentric. Having done that, I would
>then go down to in-focus, and the star image would look pretty good, and
>go further down to inside-of-focus. There, I would always find that the
>central diagonal hole was *not* concentric with the expanded disk. So,
>I'd tilt the primary so that it was. Then go back up though focus (once
>again, the star image looked pretty good) and back out to the
>outside-of-focus point. There, I would find the central diagonal hole,
>that was previously centered, was now *not* concentric with the expanded
>disk. 

Boy, have you just described what I always
thought was my problem !!?? Good to hear
someone else has the same problem <G>

> This is easy to mentally see. So using strictly
>mechanical techniques (which I'll be glad to describe, if anyone is
>interested),

If it's not too much trouble to you I'd love to hear how you
do it. 


 



Carl Brennan
Paderborn,Germany
Email: carl@pader-online.de