Assuming you've collimated the laser itself (sounds like it's not, tho) you can use the un-Barlowed return beam as a "poor man" collimation for the primary mirror. You move the primary mirror bolts until you see the return beam merge into the center hole of the back of the laser collimator.
Other option is to buy a Chesire....Which doesn't un-collimate when dropped, and never runs out of batteries!
(An uncollimated laser collimator is just an expensive lecture-style laser pointer...good for little else..).
If you have a laptop-style webcam, you can easily set it up to watch the back of the laser collimator by clipping it to the spider vane, and do "remote" collimation this way, watching the image on your laptop screen. But that's really only going to work if you have a barlowed laser technique; the bright dot of the un-barlowed laser beam doesn't image well on a webcam.
Scott
Quote:
Originally Posted by IanT
Hello everyone.
Great site for a beginner like me. Can someone please explain how to collimate the secondary mirror on a GSO (Bintel) Newt mounted on a Dob base? I'm not sure what the center screw in the 4 vane spider assembly is used for. Does it move the whole mirror up and down the OTA or allow sideways twisting? I am a bit scared to undo it! Do the three other screws simply allow a little adjustment and should I loosen them right off before attacking the big center screw? Also, I have a Saxon laser collimating thingo but it is clearly not collimated itself. It rolls around on a homemade jig and moves everytime I turn it in the focuser or even tighten it up. It doesn't have any ajusting screws or mechanisms that I can see. I tried to make a target on a Barlow in order to use the Barlowed laser technique. Unfortunately, the end of the Barlow (with the afixed target) doesn't protrude far enough to get a good view of any return beam and center spot shadow. I tried a hand mirror but it still hard to see. Any hints?
Cheers
Ian
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