Autocollimator use...

After a friend helped me check the collimation of my scope using a 2" INFINITY autocollimator last weekend (thanks, Floyd!)I decided to buy one for myself, along with a BLACKCAT cheshire. These tools will come with instructions so this post may be moot at that point, but I would like to know if I understand the process correctly from reading various posts Jim Fly's and Vic Menard's websites.

Forgive me for rehashing some of the obvious here (steps 1 & 2 come to mind...)but I want to understand.


1. Locate the secondary mirror using a sight tube. The secondary should be centered under the focuser and rotated so as to appear to be a circle, concentric with the focuser tube.

2. Next, the tilt of the secondary is adjusted so that the reflection of the primary mirror is centered within the secondary mirror. Step one may need to be revisited after this adjustment and step two checked again after that. Repeat as required...

3. Aim the secondary at the center spot of the primary using a crosshair sighttube or laser. Revisit steps 1 and 2 and adjust if necessary, verify step 3, repeat as required...

4. Using the BLACKCAT cheshire, adjust the primary mirror tilt as required to center the newly installed triangular center spot within the image of the reflective ring of the cheshire.

5. Now comes the autocollimator? If my previous adjustments have been successful I will see up to 4 reflections (1 primary, 3 ghosts?) in the autocollimator and these need to be "stacked" through small adjustments to the secondary and/or primary mirrors? How do I tell which mirror needs tweaking?

Or are these questions answered in the instructions and I'm wasting valuable bandwidth?

Thanks,

Ed

Hi Ed,
I just recently acquired the Blackcat/Infinity set.
I think I've finally got it straight.
First, I get everything pretty close with a Kendrick laser.
Then I use the Blackcat cheshire to fine tune the primary.
Next I use the autocollimator to very slightly tweak the secondary to get the ghost images to align.
Then check back again to make sure they're both perfect and you're set.
This is how I understood the directions after re-reading them several times.
(I had been leaving out the Blackcat and trying to tune the primary with the Infinity, until I read it all thoroughly.)
Good luck with yours. I think you'll really like it.
Linton

Thanks Linton and Don!

The tools should arrive next week so I'll get the chance to try the techniques you've suggested.

Thanks again,

Ed