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Laser collimator - which to buy

Started by adamsdp, 11/19/2004 11:29AM
Posted 11/19/2004 11:29AM Opening Post
I am hoping to get feedback on a good laser collimator. I have seen reports that the type with the 45 degree angled top allow for collimating a Newtonian primary from the rear
of the scope by one person. This would be great for my 12.5 f/5 Newt. All my scopes have 2" focusers. The other scopes I would want to use it with would be an 8" f/8 Newt, C9.25, D&G 5" f/10, Meade AR-6, Synt 120 f/8 and a Brandon 94. Should I get a 2" collimator? I was wondering which would be the best to get? Thanks.
Posted 11/19/2004 11:46AM #1
A 2" collimator will eliminate some of the error involved in using a laser collimator, that is from a poor fit in the focuser (between the focuser and the 2" to 1.25" adapter and between the adapter and the collimator); you can eliminate the first of these with a 2". A wrap of tape around the barrel may help to make the fit better between the collimator and the 2" focuser also.

The units that have the cut-out viewing windows that sit above the top of the focuser allow you to view the return spot from the rear of the scope, which is a big advantage; no idea why they are all not designed like this?

Another issue is that many of the less expensive laser collimators use cheap lasers with poor optics and large/irregular laser spots. Collimation with one of these involves a bit of guessing as a result. Try to get a unit with a higher quality laser and small spot size.

Lastly, you might consider the Barlowed laser method as a means of collimating your primary mirror on Newts; it is uses the laser and barlow to line up the reflection of the centre spot hole reinforcement ring (if you are using one of these) upon an opaque target placed over the bottom of the Barlow. Apparently this method is much less sensitive focuser slop issues.

Sorry no specifc recommendations as to models/manufacturers; others I'm sure will have more info.

Best regards,
Posted 11/19/2004 01:42PM #2
The Kendrick 2" with the 45° angle is a great collimator. I have one and I use it most of the time. It has nylon screws that allow you to adjust the fit to your focuser barrel size with really is nice. The starburst engraved on the face is easy to tell when the dot is centered on return. The laser is bright and runs for a long time on the batteries. Uses regualar AA batteries too.
Here is a quote from my article on lasers.
"Next in the line up is the Kendrick unit. First impression is that of a high quality well-made laser with nice fit and finish. It does not look like a laser put together from parts purchased and assembled but one that was engineered and well thought out.
The switch is well positioned and is a good rocker type that is positive in the off and on position. The barrel is machined to a close fit and has two nylon screws in the barrel for adjusting it to fit your particular focuser tube size. This is a big plus and allows you to place the laser in the barrel with repeatable results.
The 45° angle of the face of the laser and the starburst cuts in the face make it simple to see the returning beam and very accurately shows correct alignment with a symmetric starburst shape that is bright and precise. You can use it turned to the primary or toward the secondary depending on which is easier to see with your scope design.
There are four collimation screws on the barrel near the end, where they are easy to reach. Having four screws makes collimation easier and the fit of the barrel to the focuser makes it more reliable when spinning to make adjustments to the screws. Though it is not a piece of cake to collimate, it is easier than the Orion model.
I have not found anything negative to say about this laser and I find it to be a great asset to my DOB telescopes.
The laser is a class IIIA, 650 nm laser diode of less than 5 milli watts. The collimators take two AAA batteries (included). There is a one-year warranty for defects in materials and workmanship on the collimators. "

[SIZE="Large"][/SIZE][COLOR="Blue"][/COLOR] Floyd Blue grin
Amateur Imager
Posted 11/19/2004 03:06PM #3
I suggest looking at the Howie Glatter collimators. These are precision units machined by Howie himself. Tight tolerances and accurate machining, these are scientific grade tools.

The other day someone posted on S.A.A. that the Palomar Observatory had sucessfully operated an adaptive optics artifical star at 60 miles altitude.

In jest I suggested that they just needed to a laser so they could learn to star hop and that rather than spending public money they should have just contacted Howie..

Howie then responded with the information that the team at Palomar had contacted him to purchase one of his collimators for use in aligning the Adaptive Optics system.

I guess if its good enough for Palomar, its good enough for me...

Mine is 5 years old and still in measurably perfect alignment and on its first battery as well...