My+old+18+inch+Telescope

Images of the old 18 inch telescope back in our old house in the summer of 1994. It was first installed back in 1990 as a Dobsonian and was turned into an equitorial in 1992.

The link below shows a selection of observing reports and images using the telescope between 1992 and 1997. Notale observations include Comets Hale-Bopp and SLV9.

18 inch F5 Observations
The telescope was of wooden construction with a large steel (4 inch diameter) RA shaft and bearings. The run off shed is still in use and houses my 16 inch Dobsonian. The drive was a Syncronous motor with DC slew gears in RA and Dec.The RA drive had a differential gearbox so that the DC slew motors could turn the telescope without the need to disenguage the tracking motor. A hand paddle had all the controls including electric focus and filter wheel.

The telescope has now been heavily modified. See the 20 inch F4 Telescope design and construction page for more details.



Image below shows the inside of the run off shed. Two 10 inch diameter thick walled platsic tudes are used as the wheels with scaffold poles used as the axels. This allowed the shed to run off onto the grass, even if it was wet.



The imaging camera was an SBIG ST4 (still in use today). The laptop was a 386SX (16MHz) with mono screen.



Image below shows the telescope in March 1997 with the comet Hale-Bopp. Note that I had to remove a section of next doors fence to allow the telescope to lean over for imaging the comet.



Scan of one of the pages of the log I have on the telescope. The mirror was supported on bubble pack (small bubble) that was sitting on two layers of 18mm MDF. 3 collimation bolts came out of the back of the mirror cell rear plate that was bolted to the back of the mirror box. The mirror support actually worked quite well. The mirror (I was told) was made by AE Optics (John Owen maybe?)



Image below is a ronchi of my old 18 inch F5 mirror after it was dropped. This used to be in the 20 inch Observatory telescope. It was fell out of the mirror cell while transporting it from the garage to the run off shed. It was out for cleaning! Well.......it dosn't need cleaning any more!

The mirror ended up with a very large chip at the edge which is clearly visible in the image below. The surface figure is badly affected.

The mirror will be water cut out to 12 inches diamter, re-ground polished and figured. It will probably be used as a finder on the TROK to replace the 6 inch F4 that Geoff Regan made.



The image below shows the telescope in late 1990 after it was first installed as a Dobsonian.