Meade Lightbridge 12" collimation

[PaulH]

Can anyone advise me of the correct way to collimate a Lightbridge using a laser collimator?
I have recently tried to do this (at the QLD Astrofest) and it seemed to work but I'm not convinced I did it correctly.
First I inserted the laser collimator into the focuser and the beam was out slightly when hitting the primary mirror (not in the center of the ring on the mirror). I adjusted the secondary mirror so that the beam was dead centre on the primary mirror.
Next the reflected beam (coming back through the focuser) was not hitting the 45 deg angle plate in the laser dead centre so I adjusted the primary mirror screws to make the reflected beam hit the centre hole in the laser collimator.

What's confusing me is the Meade handbook saying that the Lightbridge needs collimating differently to other Newtonians, but doesn't mention collimating using a laser collimator.

Also, there are two sets of screws on the primary mirror - locking and adjusting screws. I know it sounds obvious what these are but how do these work in practice. My manual doesn't even explain this.

Any advise would be welcome. Thanks, Paul.

[Blue Skies (Jacquie)]

You need to learn about offset of the secondary when using a laser collimator (I'm sure one of the others will point you in the right direction, or do a search in the beginners forum, there has been some very good explanations about offset and lasers there in the past)

The locking screws are there to theoretically stop the primary moving once you have it collimated, but personally I just loosen them and leave them, they don't seem to much good. Other peoples milage may vary, as the Americans say.

[JethroB76 (Jeff)]

If your springs are heavy enough you are best to leave loose or do away with the locking screws.

I don't think the lock screws are actually well positioned to act as lock screws being so far away from the collimation screws.

Sorry can't help with using the laser

[tempestwizz (Brian)]

Paul,
Firstly, I have no knowledge of Meade Light Brigde systems however physics is physics, ..
From what you have said, you have done all the right things.
The other 'controls/knobs' are cosmetic, and may, or may not lock things down.
From my limited exposure to this 'range', colimation would be an essential ingredient to any re-location of equipment.
VBR
Brian

[Satchmo]

Paul

Your description of laser collimation was good, and you did it correctly.

Regards the primary collimation bolts, back off the lock screws, collimate , then tighten lock screws again.

you don't need to concern yourself with secondary offset, its only needed to ensure even light drop of at the edge of a photograpghic field, it won't effect your on axis sharpness.

Regards