A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: David Pike
Date: 2016 Apr 7, 03:19 -0700
On 3 April 2016 at 20:28, David Pike Well, I've got myself a theodolite to play with
This (I am sure) is a 'building site' theodolite and so the scales are marked in tenths of a degree or six minute intervals. This is not such an impediment as it sounds for celestial work, as it is easy to interpolate to the nearest minute.
What is an impediment to celestial work is the fact that it will (almost certainly) have no solar filter for taking sights of the sun, no right-angled viewer so you can take sights of Polaris (you cannot get your eye behind the telescope for altitudes greater than about 50 degrees), no means of illuminating the telescope cross hairs at night for taking sights of the stars and no means of illuminating the scales for reading the scales at night time.
However, on the plus side, it is almost certainly made of aluminium and so much lighter than a brass equivalent, making it handy to lug about the place. I
have a Soviet equivalent which I use for celestial work and I find it very handy to use and accurate - but I have spent a considerable amount of time and effort overcoming the deficiencies listed above! Geoffrey Kolbe
My theodolite arrived yesterday in rather bashed around packaging. There appears to be no outward damage, but there’s no way of assessing the scales until I begin using it. Perhaps it’s best not to enquire too deeply into why there’re no accessories or carrying case. There’s no detail on the device except ‘Carl Zeiss Jena made in DDR Ser. 390762’. From Google Images, I’ve been able to deduce that it’s a model ‘Theo 020A’. I could do with a manual. I was able to download a manual for the Theo 020B from eBay, but it’s a very poor translation and barely understandable to someone with no training as a surveyor. It would seem to be graduated to give readings to 20 seconds horizontally and one minute vertically. I’m already seeing its limitations, vertical readings limited to about 40 degrees, because the frame's in the way, and no electrical scale or crosshair illumination. I’ve looked at a few training videos on YouTube. I had no idea surveying was so complicated. And I thought using the Watt’s Datum Compass was pretty complicated. Still it’ll be good fun finding how to get the best out of it. On the celestial side, which is not high on my list of priorities for this machine at the moment, modifying for day operations with shades might be easier than modifying for night use with electricity. DaveP