Posts Tagged Star Testing
My recent scope acquisition: an Orion Maksutov Newton 190mm… I bought a “bundle” (brand new Atlas mount and showroom Mak Newt) in July 2009 .
I would recommend anybody buying a telescope to make this investment (artificial star and the book) and go through this procedure. It is worth it. A couple of month ago, I had to return a first Maksutov-Cassegrain because of some optical issues that was somewhat revealed looking a stars (but was not sure if it was due to turbulence or not) and the defect was revealed very clearly with the artificial star testing. I got a new scope because I was in the 30 days return policy – and the new scope was as good as the Mak-Cassegrain optical design permits…
Waiting for a great seeing to do a “real” star testing may not happen during the 30 days return policy. Make sure that when you do artificial star testing you have plenty of space – otherwise you introduce aberration that would not happen with “real” stars. In my case I placed the artificial star at least at 200 yards from the telescope.
To come back to my new Maksutov-Newton – I made the test and found (after thorough collimation) the optics extremely satisfactory, with nice diffraction patters in focus, and very similar (almost textbook-like) forward and inward out of focus diffraction patterns. Visual image of Jupiter was also crisp and contrasty, making it a good planetary instrument when well collimated, even though this is not the primary purpose of this scope (which is flat field astrophotography).
Look at the Perseus double cluster picture taken with the Mak Newton. Stars are pinpoint even at the edge of the picture (Canon EOS full frame). You would not have the same picture with a Newtonian (except if using a coma corrector) or even a regular Schmidt Cassegrain telescope.
This shot of M13 was taken with the Mak-Newt and my Qhy9 Black and White camera.
This shot of NGC 981 on this page was taken using the Mak Newton with my Canon XTi and an Orion Skyglow filter.