Barlowed laser collimation

[moflaher]

A theoretical question:

Does anyone now how accurate is the barlowed laser collimation method for scope faster than F5?

I am a huge fan of the method and I am using this method to collimate a f5 with a badly collimated laser collimation and my results are for visual purposes very good and achieved in a few minutes (if no seconds!). Stars test are not of textbook quality examples, but I can see diffractions rings concentrical, and some times even a central point.

However, I wonder if I can learn something about the accuracy of the method in general, and in particular in scopes that are more demanding in collimation quality.

[acey]

It's as accurate as using a Cheshire, though how exactly one should quantify and measure that accuracy is another matter.

How do you end up with "central points" in the star test? There ought to be a black disc: the shadow of the secondary.

[angusb1]

I used it to collimate an f4. Worked well for me

[John]

I use it with my 10" F/4.8 and find it very effective.

[Jason D]

There are 3 independent collimation alignments:

1- Centering the secondary mirror under the focuser for optimal illumination

2- Adjusting the secondary mirror to eliminate eyepiece/primary focal planes tilt

3- Adjusting the primary mirror to eliminate eyepiece/primary focal points shift

Barlowed laser only takes care of the third alignment – which happens to be the most critical. It does nothing to the first two.

Jason

[ismangil]

I've read about barlowed laser, I tried it but couldn't see a proper shadow of the center spot in the collimator windows, which articles say is a dark spot in a diffuse laser beam?

Did I do anything wrong?