What collimation tool. Laser or Cheshire?

[Charic]

Its usually only the primary mirror that needs or gets a final tweak, say after moving the scope by car over rough ground, and on such an occasion, a Barlowed laser works well for checking the scopes mirror alignment on your arrival, and with this method of inspection its fast and quick and  does not require a 100% calibrated collimated laser.

Until you buy a laser you won't know. I felt it was necessary  to have one, and after watching videos I decided I needed one. I built the jig out of  'PVC' Pipe and calibrated away to get a static laser spot at about 18 feet away, good enough for me. But once I have collimated and taken the Laser out, have a cup of tea, put the laser back in, its not the same (sometimes) due to the sloppiness of the fitting, but that can be cured, but these days I rely solely on the Barlowed laser, rather than the laser itself, when out in the field, so to speak. 

[SteveBz]

Hi Ross,

They're all great tools, and I had the same problems as you.  I read Astrobaby's write up and everyone else's, but I had never seen an Airy disc, and then for the first time this week, I understood it.

You are just trying to get the centre of the focal plan on the eyepiece.  It doesn't matter if everything is skew as long as the focal point ends up in the right place.

I took off the eyepiece holder attachment leaving a 50mm gap, and there you can see an image of your eye.  Move your eye around until all the bits are straight and aligned and maybe you won't have a complete image.  Whatever tools you use, that's what you have to fix.  Now get the broad alignment right with no tools, then start to use your favourite tool to fine tune it.

Suddenly, I had a perfectly collimated scope Airy discs and all.

Good luck

Steve.

[SteveBz]

4 hours ago, SteveBz said:

Hi Ross,

They're all great tools, and I had the same problems as you.  I read Astrobaby's write up and everyone else's, but I had never seen an Airy disc, and then for the first time this week, I understood it.

You are just trying to get the centre of the focal plan on the eyepiece.  It doesn't matter if everything is skew as long as the focal point ends up in the right place.

I took off the eyepiece holder attachment leaving a 50mm gap, and there you can see an image of your eye.  Move your eye around until all the bits are straight and aligned and maybe you won't have a complete image.  Whatever tools you use, that's what you have to fix.  Now get the broad alignment right with no tools, then start to use your favourite tool to fine tune it.

Suddenly, I had a perfectly collimated scope Airy discs and all.

Good luck

Steve.

Actually, here's a link to the webpage that introduced me to it.

http://garyseronik.com/a-beginners-guide-to-collimation/

[Charic]

5 hours ago, SteveBz said:

Suddenly, I had a perfectly collimated scope Airy discs and all

Thats the great feeling you get once you have become a master?

You can't break collimation, just unsettle it, but once mastered, most folk can look back and wonder what all the fuss was about, its like anything else, once you know and understand it becomes second nature and amazingly quick?  and when you reach this stage, your also fully aware of what the next person is going through.