20+inch+F4+original+telescope+design

The telescope in the dome used to be an 18 inch F5 equitorial telescope that was kept in a simple run off shed in our old house. Over time (since 1992) It has gone through many changes. See My old 18 inch Telescope for more details.

A few years after we moved house (1997), the telescope was then re-designed as an Altazimuth telescope and fitted with mel Bartels stepper system (this was around 1999). It was installed in the run off shed and was used for a number of years as shown in the image below.

I obtained the dome in bits back in 2003 and began the design of the Observatory. I then re-designed the mirror cell during this period. While putting the mirror back in it's new cell I dropped the 18 inch mirror. The mirror was replaced with a 20 inch F4 mirror that is in use today.

The CCD camera was located at the prime focus of the telescope. This made for a simple design with low wind loading. But it was difficult to align. The telescope is now driven by a servo system from Sidereal Technology and the telescope now has a conventional top end cage with a de-rotator.

Report on the re-build of the 18 inch telescope