Collimating a Telescope

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  • Thread starter Drakkith
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  • #1
Drakkith
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Main Question or Discussion Point

Hello! I purchased a 130 mm reflecting telescope a few months ago. I recently have had to try to collimate it due to the mirrors being out of alignment, but I'm not sure I'm getting it 100% correct. I follow the directions in the instruction manual, but it seems that even when I think it's perfect it still seems to be off when I look at something through it.

I tried a laser collimating tool i purchased, but it is effectively useless. The instructions don't seem to match what I see on my scope and the dot is pretty much always in the center of the collimating tool. (WTF is a donut in reference to a telescope?)

Does anyone have some suggestions? I'm not 100% sure if the distortions I'm seeing through my scope are due to the alignment being off or because of atmospheric effects. Thanks.
 

Answers and Replies

  • #2
russ_watters
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I had a laser tool too and didn't like it. The best way is on a night with good seeing, using a star. Google "star test collimation". In short, though:

The process is two steps:
1. First view a star out of focus so you see a big doughnut. The outer and inner rings of the doughnut should be perfectly concentric. If not, adjust until they are.
2. Focus the star (you may need a dimmer star). You should see a point of light with concentric circles around it (diffraction rings). If not, adjust until they are.

Here's a good guide I've used: http://legault.perso.sfr.fr/collim.html
 
  • #3
Drakkith
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Thanks, I'll look it up. Also, the donut thing was from the instructions on the Laser Collimater. It said to make sure the dot was inside the donut. It would brighten when it was on top of the donut, and dim again once it was inside the donut. No idea what they were talking about with that.
 
  • #4
Chronos
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