Laser confused

[j4y7223]

Hello! Hope I'm posting this in the right place, this is all new to me, I will try to get to the point as quick as I can. I've recently purchased my first Reflector Telescope a Sky watcher 130M, knowing it would need collimating I purchased a laser collimating tool. Having heard that laser also need to be checked that they are correctly collimated, that's the first thing I checked, and it was spot on. So, having watched endless how-to videos on YouTube, I went through the motions of collimating until everything was perfect on both secondary and primary BUT! When I looked down the focuser it looked like.......... Well, let's just say, AWFUL! Nothing lined up. After several frustrating attempts later I did away with the laser and went back to basics and made myself a collimating cap and re-collimated. Everything now looks perfect though the collimating cap, lined up and central. But when I put the laser in, it's saying it's out, not by a little, a country mile................WHAT! My gut feeling tells me the cap method must be right and lasers lie. If anybody knows what might be going on here or tell me what I may be doing wrong will be much appreciated.

[johninderby]

Have you read this guide?

http://www.astro-baby.com/astrobaby/help/collimation-guide-newtonian-reflector/

 

[McNewt]

1. When you have the laser in, if you bend it gently from side to side. does it move?  Slight movement usually makes the laser go all over the place.

2. Is the secondary centered in the tube?   I have a 130mm newtonian that, initially, was impossibe to collimate.  When checking the placement of the secondary I discovered that the opening end of the tube wasn't round.  After having fixed that the collimation process was quite a bit easier.

 

Edited October 12, 2019 by McNewt

[westmarch]

Hi there,

The cap method is simple and always gets you into the general ball park.  The acid test is to check it, then your laser collimation, against a real star.

This is a good guide to star testing:

https://popastro.com/documents/PA_jan-mar2009_p12-13_telescopetopics_startesting.pdf

Good Luck

John 

 

[j4y7223]

• Thank you, John, I'll definitely take a look .

[j4y7223]

• Hi, it did move a little but I shimmed it so it now fits good and tight, and yes I have checked the 2nd mirror it seems to be fine.