laser collimator

Hey forum
Does anybody have experience in laser collimation,
basically is it as great as its supposed to be, for someone who has a 10" dob and doesn't want to loose as much of the precious light as possible?

Also does the routine of laser collimation (or collimation in general) actually line the two mirrors in the approximate centre of the tube or just give them a common centre of axies (some scopes have a 10" mirror in a 12" tube so getting centre is quiet roughly done)?


THankS
Michael

Yes it makes a big difference and it is very easy to use. I still do a quick star check after collimation just to make sure its perfect. It helps if your primary mirror center is marked. Most new scopes come with a circle applied to the center of the primary mirror. Most Collimators come with this circle if your mirror is not maked. I use the Orion
LaserMate Deluxe Collimator on my 10”.

Good luck

Also does the routine of laser collimation (or collimation in general) actually line the two mirrors in the approximate centre of the tube or just give them a common centre of axies (some scopes have a 10" mirror in a 12" tube so getting centre is quiet roughly done)?

Hi Michael,

Laser collimation does not help you get the mirror centered in the tube, however being perfectly centered is not absolutely crucial. As long as the mirror is visually centered, that is fine. What is crucial is accurately lining up the optics. A laser collimator will get this much more accurate than your eye alone will allow.

Good luck.

Cheers to Jim and Dave

Thanks for the advice, i will purchase the orion LaserMate!!!

Thanks
Michael

A laser collimator will get this much more accurate than your eye alone will allow.

Good luck.

Hmm, well, yes and no.

The main problem with laser collimators is how they are supported in the focuser. They have to be aligned perfectly perpendicular to the OTA in order to get the beam of light in an accurate path to the primary and secondary mirrors.

In alot of focusers, screws are used instead of compression rings. What happens here is that the collimator doesn't have a correct fit in the focuser and the tightening of the screw distorts the alignment of the beam. Result: you're laser collimator points a beam of light in the wrong direction/angle. It may be only off by a few degrees, but this becomes significant by the time the beam hits the secondary, bounces off the primary, back up to the seconday and back out to the focuser.

Before you spend your money, my advice is to get an old 35mm film canister, punch a small hole in the base, and place the canister into the focuser. It should fit very nicely. For further info, read: www.lymax.com/cosmicone/collimator/index.shtml

When you have the collimation reasonably accurate, use a high power eyepiece to fine tune.

Clear skies,

Laser collimators do have their uses - especially for open truss Dobs that have to be assembled every time they are used. They are of limited use with a solid tubed scope as you can not see the reflections on the secondary mirror or the return spot in the focuser tube.

I said of limited use - From my own experience, collimating from scratch with a laser can result in a truely horrible alignment! The laser tells you everything is spot on but the star test says diferent. Lasers are very useful for doing quick tweaks to the primary mirror once you have done a very accurate and critical collimating job on the secondary cage (focuser and mirror alignment and offset is very important) and have or can ensure that the primary mirror is or can be centred in its cell repeatably. To do this kind of collimation you need to get your hands on a good Cheshire eyepiece and cross-hair sighting tube. An auto-collimating eyepiece is also very useful for super-tuning the alignment. Tektronics used to sell an excellent set of three collimating eyepieces (Cross-hair sighting tube, Cheshire and autocollimator) and I would recommend you get these rather than the Orion collimating eyepiece (which combines a Cheshire and a cross-hair... badly!)

One final problem I found with the Orion laser collimator is that it tends to wobble slightly in my JMI NGF focuser! I know the focuser tube is accurately round, so I suspect the laser barrel isn't, or is slightly too small! The upshot is that you can get great alignment... until you touch the laser and it moves

Bottom line - if you have a closed/solid tube then stick with the non-laser option.

Phil.