I'M ABOUT TO LOSE MY MIND! HELP!

HELP!!!

I'M ABOUT TO LOSE MY MIND!! I'm trying to collimate a Newtonian and I'm having no success what so ever. This thing is kicking my butt. I've bought an Obsession 15" f/4.5 and I'm having to install the secondary from scratch. But I can't get the Cheshire and the Laser to agree at all. I can get close but that's it. I've messed with collimation for about 2 weeks off and on but end up with same results.

I've read every book and web site on the subject it hasn't helped. Is there a collimation guru that happens to live close by (High Point, Greensboro NC). I'm in need of hands on training.

Thanks,
David Pope

David,

It can be difficult to install a secondary before you are proficient in other aspects of collimation. In placing the secondary, one normally proceeds in steps.

Step 1 is to fix how far the secondary is from the primary. looking through the Cheshire it should appear centered top to bottom (I am speaking as if the scope were pointing straight up).

Step 2 is to fix it's rotational position so that it faces the focuser. This is tricky because it depends on the tilt which you haven't adjusted yet. There is a way to get it right very quickly, but rather than overload you with shortcuts, let me just say that you should adjust the rotational position, then adjust the tilt. If it no longer appears centered left-to-right after you adjust the tilt with the laser, rotate it slightly in the direction that it is cocked and readjust the tilt with the laser. Eventually it should appear centered left-to-right and top-to-bottom with the laser being directed to the primary center. Do not bother to proceed to adjust the primary until you have achieved this! And after you have achieved it, leave the secondary alone!

Once the secondary is properly adjusted, you should NOT try to make the return beam of the laser agree with the Cheshire. Use the laser for a ROUGH alignment of the primary because that's all it's good for as is. Don't even worry about "tweaking it in" so that the beam returns exactly to its source. Instead, once you are close, switch to the Cheshire and TRUST it. The laser will magnify a number of small sources of error that are not relevant in adjusting the primary, so don't worry if the Cheshire says the primary is aligned and the laser says "not quite". The Cheshire is correct.
--
Mike

David,
I'm no collimation guru, but I live near Winston-Salem and have a 20" Obsession. Drop me a line at [email protected]

Jeff