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Matt when using the laser in a cradle technique aiming at a distant target the idea is to mark the spot and then rotate the laser 90 degrees and mark again. You want the spot marks grouped as close as possible. The problem with your refractor test is that the result is the same in each scope, regardless of focal length - which just seems wrong as it should be further out on a long scope if its the laser alignment. Stick to the spot grouping against a target. I tuned mine to a tight group of spots , with 1/2" circle at a distance of five metres - good enough for any reflector or refractor. I also used it to collimate my iStar build refractor focuser and it was perfect. You should only use the laser to align the focuser to a centre spot on the obective (or a target taped over it) and then use the Chesire from there to merge the reflective spots on the objective using the push/pull cell screws - stuff I am sure you know.
Of course Lasers are known for tube slop, the tube of the laser maybe too narrow to allow a close fit in your focuser and is sagging slightly in the focuser and that causes the spot to appear off centre. I have a very thin shim of plastic that I use to create a good close fit for the laser in the focuser tube. If you rotate the laser in the refractor focuser does the spot stay in about the same place - a good indication that the laser is sagging in the focuser tube. If you lift up on the laser does it move the spot?
Last edited by glend; 12-06-2014 at 08:44 PM.
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