Collimation Issue

[Razz]

I just collimated my AD10. I used a collimation cap and Cheshire. As this is my first time, I followed Astro Baby's tutorial. The secondary mirror appeared to be okay but the primary was off a little. I adjusted it so the crosshairs were centered on the dot. I went thru this 2 more times just to verify it. I then put the laser collimator that I got with the scope in. It was off about 3/4" from the center circle looking at it down the tube. I rotated the laser and the position never changed. Could it still be the laser itself is out of collimation or did I not collimate the scope correctly?

Edit: I think I figured it out. The secondary is not right.

[Razz]

Ok, so the first time I did this, I could see the 3 mirror clips in the collimation cap. They seemed to be equal. I reread the tutorial. Seems I didn't have it centered to the focuser tube. So I adjusted the secondary so the dark area around the image was equal. I then readjusted the primary. I put the laser collimater in and it's in the same spot as it was originally or very close to it. Ok, this is new to me so let's experiment. I used the laser to collimate the scope and then checked it with the cap and Cheshire. The cap showed very clearly that the secondary was not centered to the focuser tube. Then I used the Cheshire and the primary was off just a little. I'm clearly doing something wrong.

[John Baars]

If you didn't collimate the laser, but used it like you bought it from the shelve, I would believe the Cheshire.

[Razz]

Thanks for the reply. I didn't collimate the laser. I'll go with the Cheshire then.

[SkyHiker]

You rotated your laser and it stayed in the same spot so your laser is fine. Trust it, especially for collimating the secondary. You backed out for the wrong reason. The image of the secondary is not supposed to be symmetrical, from basic geometry. See Don Pensack's article https://www.catseyecollimation.com/pensack.pdf .

[Razz]

You rotated your laser and it stayed in the same spot so your laser is fine. Trust it, especially for collimating the secondary. You backed out for the wrong reason. The image of the secondary is not supposed to be symmetrical, from basic geometry. See Don Pensack's article https://www.catseyecollimation.com/pensack.pdf .

Thanks for the link. Very informative article. I wasn't thinking about basic geometry, I was just trying to follow the tutorial. I'm not sure what I backed out of though...I'm just trying to figure out what I'm doing.