XT10i Telescope used as a Theodolite / Laser Level

Posted by XTSee on 29th April , 2009

Just lately I’ve been too busy with a completely different kind of project for me to do any astronomy, hence the rather long delay between my previous blog post and now.

We have been completely absorbed in the evenings designing a new pond for our fish. Basically the original pond (at 400 gallons) was too small for the number of fish (golden orfe, sarasa comets, shubunkins and ghost koi) which have after 5 years far outgrown the size of pond. The biggest fish (the koi) are about 16-18 inches long, and very fat.

Also we have been wanting to create a new patio area in the garden, part of which is in a darker part of the garden, which I plan to use for viewing the night sky! Yes, a cunning plan with an ulterior motive too. :)


Part of the design work has been to use some landscape design software (Realtime Landscape Pro) to show a 3D view of the house, garden and pond/patio area, and of course this entailed accurately plotting the levels and contours of the ground which slopes to varying heights across our back yard.

Well, since I didn’t have a laser-level or theodolite to hand, I decided to use my XT10i for a new purpose other than observing the night sky! By levelling the base carefully on level ground using a spirit level, and aligning the main telescope tube exactly horizontal using a spirit level, I was able to defocus the 9×50 finder scope (which has cross-hairs) close enough to be able to focus on a 2 metre long piece of wood held vertically, to which I attached a clearly marked tape measure, with zero point on the bottom of the piece of wood. The main scope would not be able to focus this closely, nor do I have any eyepieces with cross-hairs which are essential for accurately reading off the dimensions. The nearest I was able to focus was just within about 5 metres of the finder scope.

By swinging the telescope around in azimuth only (being careful to ensure the altitude adjustment was locked tight and the scope kept horizontal) I was able to view different parts of the garden and align it on the measure held at various places around the plot. I could read off the measurement to ground level, and so work out the different levels above the lowest (”zero”) point of the garden. Once I had these measurements I entered them into the height grid contour points feature of the software, and so plot the contours of the land in the 3D view of the garden.

With this done I could carefully plan the position and necessary level differences and heights of the new patio and pond. The pond project is well into construction, and the new home for our fish will be 2100 gallons capacity.

See - my trusty XT10i telescope serves me well in the strangest ways! And saved me the cost of buying or hiring expensive (one use only) levelling equipment. And when the patio area is finally complete I will have a better location for observing the heavens. Perfect.

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2 Responses to “XT10i Telescope used as a Theodolite / Laser Level”

  1. Koi Pond finished - Back to Astronomy! | Jims Orion XT10 Astronomy Blog

    [...] last blog post was back in April when I had used my XT10i telescope as a theodolite measuring levels for my new pond. Hooray - The last slab has been [...]

  2. Mark (2 comments)

    Nice Idea, but if you need laser levels try stabila4u.co.uk

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