The primary telescope is a customised 305mm (12-inch) f/5 Newtonian reflector telescope mounted on a heavy duty German equatorial mount with a 114mm (4.5-inch) f/18 guide-scope.

The primary telescope, from GSO optical, was supplied by The Binocular & Telescope Shop and then modified to suit astrophotography. The modifications consisted of improving the telescope's image contrast by installing light baffles inside the telescope tube and stopping stray light from entering the telescope around the focuser mount and primary mirror mount. These modifications improved the image contrast tremendously.

Some extreme modifications required the telescope optics be moved 48.5 mm closer together so that an attached camera and its adapters would easily reach the telescope's prime focus. The telescope was intended to be used as a Dobsonian and certainly focused well for that purpose without these modifications.

The primary telescope has a 2-inch Crayford style focuser and 2-inch camera adapters, accordingly there is no vignetting in the resulting images.

The Guidescope.

The guidescope is a 4.5-inch f/9 Newtonian reflector with a 2x Barlow lens for guiding at f/18 that I originally purchased from a local optics dealer. The guide-scope is fitted to the main mount with brackets I made from aluminium plate and flat iron strap turned into guide-scope rings hold and adjust the pointing position of the guide-scope relative to the primary scope.

The German-style Equatorial Telescope Mount.

The German-style equatorial mount (originally purchased from Astro Optical Supplies and called the Samson mount) has 1.25" steel shafts on both axis making this a heavy duty mount. I recently computerised the mount with an Argo Navis™ and encoder gear sets I had manufactured to fit the mount.

Encoders and Axel Gears.

The main encoder gears are 90mm diameter with 178 teeth fitted to both the R.A. and Dec. axis and are locked into position with 3 grub screws at 120° spacing. The smaller 30mm diameter gears fitted to the optical encoders have 58 teeth and a single grub screw to lock them into position. Altogether this provides 25,141 steps per revolution of the telescope which equates to a telescope pointing accuracy of 0.8 arc minutes.

This allows STAR Atlas:PRO™ to monitor the telescope's pointing position and of course allows me to easily locate deep sky objects. The mount has a 150mm diameter R.A. drive gear, 50Hz variable frequency drive and the drive corrector to manually correct R.A. tracking errors.  A tangent arm is used for manually correcting Dec. errors.

2005 - Paul Mayo paulm@skylab.com.au

Observatory Location
West of Newcastle city, NSW. Australia.
151° East, 32° South

 

Equipment Currently Used.

305mm (12") f/5 GSO Newtonian telescope.

Samson German style Equatorial Mount (circa 1980's).

150mm (6") StarDrive R.A. Drive Unit.

Hand held controller and drive corrector for R.A. drive unit with faster, slower and bias corrections.

4.5" f/9 Newtonian telescope acting as a guidescope with 2x barlow.

9.5mm orthoscopic guiding eyepiece with variable illuminated reticle.

2" Baader Multi-purpose Coma Corrector.

2" Baader UV/IR Cut Filter.

2" Crayford style GSO focuser.

Modified Canon 300D Digital SLR with clear class CMOS window.

Argo Navis Digital Telescope Computer with high resolution optical encoders.

IBM Thinkpad Laptop with RS-232C port.