Refractor Focuser Alignment

Started by rnabholz, 10/11/2003 09:54PM
Posted 10/11/2003 09:54PM Opening Post
I recently acquired a collimation laser and I thought I would check the alignment of my refractor's focuser, which I had my suspicions about.

I cut a disk out of a manilla folder matching the inside diameter of the dew shield and inserted it in the shield up against the front of the lens cell. The center marked for reference.

It seems that indeed the focuser is not square. The laser's dot misses the center mark by about 3mm. (4" f10 by the way)

My question: Is this enough error to worry about? The focuser is not adjustable so I will have to undertake some work to bring it true, and am wondering if I will see a noticable improvement in performance for the trouble.

Thanks

By the way, I also got multiple return dots on the laser (EZCollimator) so I am also wondering about the cell's alignment too.

Rod Nabholz
Home Built Astronomy Projects
http://www.homebuiltastronomy.com/
Wild Bird Photography
http://www.wildsideiowa.com
Posted 10/11/2003 11:55PM #1
Hi Rod,

If you do a high power startest with a green filter and the rings look concentric I would not fool with it at all. If the startest shows the scope to be out of collimation then it would probably be worth trying to fix it. I would also suggest doing the startest with and without a diagonal. I have a TV 1.25" standard diagonal that is so bad I would sooner throw it away than pawn it off on someone else.

Clear Skies,

Steve