Observatory-Bare-12 F4

At present, CCD imaging is being done with a carbon fiber truss, 12-1/2” f/4 corrected Newtonian telescope I completed building in 2008. It was quite a challenge, and involved a bit of custom design and fabrication of truss plates, truss components, etc. The results have been an extremely stable focus and a vert rigid OTA structure.

On this scope, the imaging train is a 3” Keller corrector, PDF focuser, and Sbig STL11000 camera with AstroDon L,R,G,B, and Ha filters installed. The primary mirror is a 12-1/2” f/4 from R.F. Royce and a 5” secondary mirror from Ostahowski Optics.

This all sits atop a Paramount ME, utilizing a variety of software for control and acquisition including TheSky6/Tpoint, MaximDL, FocusMax, AAG Tpoint Mapper, PinPoint Astrometric engine, and CCDautopilot.

Scondary Vanes-Thin View1

This view of the secondary cage shows the top plate with secondary vanes and hub. In this design, I had the top plate, secondary vanes and hub at it’s correct offset milled out of a single block of aluminum. This enables me to keep the vanes in perfect alignment, with the typical Newtonian secondary offset (0.31” fo this system) set precisely. Care needs to be taken in this type of design, to be sure the weight of the secondary mirror doesn’t cause rotational movement through the different orientations of the OTA. This type of design enables precision mechanical collimation of the focuser along the optical axis, as oriented to the secondary mirror, which makes the process of optical collimation easier and more repeatable. Update: I’ve since replaced the secondary spyder system with a double-vaned stainless steel arrangement, which holds the heavy 5” secondary in collimation very well through all orientations in the sky.

ImageTrain1 OstahowskiSecondary
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