Deepsky Equipment - Pieter Vandevelde

Newtonian Astrograph

My main deepsky scope is a 10" f/3.8 astrograph (own design and homemade with the exception of the mirrors and corrector)

The mechanical design work and all finite element analysis (fea) was done in Pro/Engineer.

I did some tests with existing (third party) mirrorholders, but was not impressed with the collimation stability and build quality. The primary and secondary mirrors are supported using spherical bearings in custom made cnc machined supports. 6-point primary mirror floatation cell defined using PLOP.

The primary mirror with Hilux coating (10" f/4 Research grade) was custom made by Orion Optics from 1" thick Suprax glass. The 4" secondary mirror (1/15th wave PV) was made by Antares Optics. The double vaned spider is my own design using 0.5 mm cnc cut stainless steel vanes. The collimation is tool-less. Baffles in front of the primary and spider are machined out of pertinax.

The secondary has a Kendrick anti-dew pad integrated into the mirror stalk. The primary is cooled with 3 rear mounted fans and 2 cross blowing fans scrape the boundary layer from the main mirror's surface. The variable heater control and fan speed controllers are also home made.

The focuser started out as a 3" JMI event horizon focuser but was totally modified to accomodate a 3" ASA Wynne corrector. In the end all the parts were redesigned/remade. Focusing is automated using a beltdriven Rigel absolute focusing system.

The tube rings and focuser stiffners are cnc waterjet 20mm thick aluminum pieces. The tube itself is an 11 mm thick carbonfibre/aramid honeycomb sandwich tube made by Klaus Helmerichs. The waiting period for the tube was almost 5 months but it is an impressive piece of workmanship. The true honeycomb sandwich construction gives superior stiffness compared to single walled tubes. Stainless steel hardware is used throughout the scope.


Mount

I gradually upgraded mounts over the years as my imaging progressed: a Vixen gp-dx, Losmandy gm8 (utter piece of crap), Takahashi em-200 (great!) came and went. Currently I am using a Mesu 200 friction drive mount, after some startup problems it is proving to be extremely accurate and robust. This mount is built (and some say looks) like a tank, which is exactly what is needed in deepsky imaging.


Imaging sensors

My current deepsky ccd camera is an sbig st-8300M. It came of the very first batch made by sbig using the now popular KAF8300 sensor. During deepsky exposures a Lodestar guidecam is used in combination with an off-axis guider.

During the years the following cameras were used: Homemade LX mod webcam, Starlight Xpress mx7c, Starlight Xpress sxv-h9.