laser collimators for Dobs

Hi, just got my first ever dob, so I was wondering if anyone could help:
(a) who makes the best laser collimator?
(b) if it is well made, i.e. doesn't rock around the focuser, is aligned, etc., is it the recommended method in the field?

Thanks very much,
Ivan

I use a Howie Glatter - works great!

I will vote for LaserMax, really useful hologram display for use in many types of scopes.

Ivan Ong said:

Hi, just got my first ever dob, so I was wondering if anyone could help:
(a) who makes the best laser collimator?
(b) if it is well made, i.e. doesn't rock around the focuser, is aligned, etc., is it the recommended method in the field?

Thanks very much,
Ivan

My vote goes to Howie Glatter. www.collimator.com

Howie makes them himself, he has a machine shop in his home and he's a one man show. His collimators are very simple, very precisely made, very accurately aligned and very robust, they stay start out aligned and they stay aligned. And if something goes wrong, he can repair it for you...

The specification on the precision of the alignment is 15 arc-seconds... That's 1 millimeter at 45 feet. My original 1.25 inch Howie Glatter stayed in "perfect collimation" for about 8 years, then I dropped it about 6 feet onto the concrete in my garage. That knocked it slightly out of collimation...

As far as the fit in the focuser, since Howie machines them himself, they are a nice slip fit... No rocking but not so tight as to bind...

A few years ago, the folks at Palomar were needed a couple of collimators to align the artificial star projection system they now use as part of their Adaptive Optics for the 200 inch. They looked around and liked what they saw so they purchased a couple of collimators from Howie..

I now have a second collimator, a two incher with all the bells and whistles, including the Blug. He does good work. He's the Roland Christen of the laser collimator world....

Jon

Not to change the subject, but which Dob did you end up with Ivan?

John

Howie will certainly get a lot of votes, as will a number of other manufacturers.

If you are looking for something that will always be tight in your focuser, try Hotech. It's 1.25" fits into its own special 2" adapter. Both have a "self centering" mechanism. You turn the centering ring, and a rubber collar centers and locks the collimator in place.

Note, however, that this is no guarantee that the beam will always be in the same place. You have already been told about laser beams that are not in themselves centered. In addition, you may have a problem if your "2" inch inside diameter focusing tube is not the same "2" inch outside diameter as the collimator. Two inches, in other words, is not always two inches when one starts machining. If your focuser itself is not tight, that slop will move the beam from one insertion to another. And if the set screw that you use to hold the collimator tight in the tube is tightened incorrectly, then you may inadvetently adjust where the beam goes.....All collimators are subject to these vissicitudes. Quality collimators overcome them by centering the laser better, having better machining, and such. But, a sloppy focuser will still let the beam vary between insertions.

The real advantage of the Hotech is that it centers itself, and locks without using the setscrew. So, at least it helps overcome some of the problems from mismatch between the focusers 2 inch, and the collimator's ideas 2 inch. It also keeps the collimator locked in place during the collimation. And since you do not use a setscrew, you are not changing the location of the collimator.

But, hey, we may be splitting hairs somewhat here. If you want really good collimation, get yourself a quality laser collimator, yes. (Almost any of the premium quality lasers will work well. And the inexpensive also work pretty darn well, also.)But also get yourself a sight tube/Cheshire, and learn how to use the stars themselves as collimation targets.


Alex