Collimate the collimater ?

[abberation]

I have collimated my 12" dob and just out of interest, when I thought I had finished I rotated the collimater 180 degrees.

I was surprised to see the laser dot off centre. I'm not sure but guess the reasons are collimater out of adjustment, and possibly the eyepiece

not exactly at right angles to the optical axis. 

I recollimated using the mean position.

Any comments/advice appreciated.

Richf

[wookie1965]

My laser was out i used a piece of electrical conduit to put it on to collimate it but it is still very slightly out like yours i just use my Cheshire now.

[Charic]

abberation...........does the laser barrel have any indents  maybe (3)  and  silicon/rubber filled ( one may be under the label) These can be removed to access the adjusters to collimate the collimator?

[abberation]

Thanks for the replies - I will check out if I am able to adjust the collimater, also I will compare the laser adjustment with the cheshire to see if it is some where near. Thanks again.

[AndyWB]

There have been a few threads about this around (I had the same question) - e.g. http://stargazerslounge.com/topic/197385-collimating-the-laser-a-right-pain/ - I did read somewhere that a cradle of 4 nails in 2 X's is good. You then shine the laser on a distant wall, and as you rotate the collimator, if it's aligned, the laser should stay in the same spot.

[Bart]

There have been a few threads about this around (I had the same question) - e.g. http://stargazerslounge.com/topic/197385-collimating-the-laser-a-right-pain/ - I did read somewhere that a cradle of 4 nails in 2 X's is good. You then shine the laser on a distant wall, and as you rotate the collimator, if it's aligned, the laser should stay in the same spot.

I did this and it works great. I also use the barlowed laser technique for collimating the primary. Dead easy and quick. If you want to make sure, then stick in the cheshire to really fine adjust.

Barry

[abberation]

Once again thanks for the informative replies - you never stop learning!