SW MN190: how to re-spot secondary?

[toc (Tim)]

Looking for advice/help - I was cleaning my Skywatcher MN190 secondary and it looks like the secondary spot came off - any tips on how I might re-spot?

[Stonius (Markus)]

Can you trace around the mirror onto some paper then cut out the resultant circle? If you can, all you need to do is fold that paper circle in half one way then the other. Where the folds meet is the center of your mirror.


Hope that helps.


Markus

[glend (Glen)]

Don't try it. Do not assume the secondary spot is centred in a traditional way. The secondary spot is used by the factory optics team for initial alignment and has no practical use to owners. This has been discussed on the Cloudy Nights forum in previous years. I am dismayed when I hear that people have tried to mess with the MN190, as the secondary setup is critical to performance and much less forgiving than a normal Newt. In particular never try yo mess with the secondary offset, it is factory set and critical, as it is mounted directly onto the rear of the corrector. This is one reason that after market focuser upgrades usually fail (unless the Moonlight and its special adaptor is used). Leave it alone.

[toc (Tim)]

Originally Posted by glend

Don't try it. Do not assume the secondary spot is centred in a traditional way. The secondary spot is used by the factory optics team for initial alignment and has no practical use to owners. This has been discussed on the Cloudy Nights forum in previous years. I am dismayed when I hear that people have tried to mess with the MN190, as the secondary setup is critical to performance and much less forgiving than a normal Newt. In particular never try yo mess with the secondary offset, it is factory set and critical, as it is mounted directly onto the rear of the corrector. This is one reason that after market focuser upgrades usually fail (unless the Moonlight and its special adaptor is used). Leave it alone.

Was hoping you would comment Glenn - I dont think the manual even mentions the secondary dot - some people use a cheshire and try to align the cheshire cross hairs with the secondary dot, but it sounds like that is a bad idea!