Quote:
Originally Posted by alistairsam
Very nice work Rolf. Looks great and like Mike said, you have a winning combination going.
Can you explain how you centered the secondary wrt to the OTA.
That seems to be my biggest problem, and have you tested collimation at different orientations using a laser and slewing to different angles to see if collimation holds?
I would've thought the weight of the secondary would stretch the strings slightly at different angles.
Are you using threaded adaptors for the focuser?
Cheers
Alistair
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Hi Alistair, I just centered it approximately with a ruler. Once the strings are attached it's very easy to make adjustments in all three dimensions so that was no problem.
There are varied opinions on this topic but my philosophy is that it doesn't have to be perfectly centered, as long as collimation is perfect all is good. Collimation only requires the optical axis of the primary to coincide with that of the camera/eyepiece. Once that is achieved (I use star testing) then it really doesn't matter which direction the mirror points in and wether the secondary is centered and if the focuser is squared and all that kind of stuff. As long as there are no obstructions in the light path of course, otherwise you'll get vignetting to a degree.
I've tested different orientations and collimation holds fine, there was no observable shift. This is also because the secondary is hold solidly in place due to the geometry of the strings, not their tension.
I'm just using the compression-ring of the Moonlite focuser, it holds very firmly on to the Baader MPCC which sits completely square. I was happy that there was no issue with that
