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my two cents worth- can i get change from five?
my portable ob consists of old 25mm white poly retic line (dug up during another project) , builders film, and that white 2mm under floor insulation. cut poly and join with 4 elbows to form a rectangle approx 2000 x 1200 mm (depending on width of film and insulation) stretch insulation and tape, top to bottom, then wrap in film and tape it all up. (stop ingress of condensation).7 of these panels, joined with cable ties, form the walls, and can be folded up, concertina style. they take up a space 2 x 1.2 x .2 m, and it weighs bugger all. the roof is made of the same stuff, bent and tied to make two half hemispherical domes, ( hope that makes sense!) that sit on top of the walls ( well a poly ring, same diameter as the wall structure, cable tied in place), one a little smaller than the other, so that it can slide into the other, leaving a section of roof open for observing. the scope sits on four paving slabs which i leave out in the sun all day to warm up, these provide some thermal mass, causing updraft, which seems to minimise condensation in scope ( 10" dob), and keep my feet warmer than freezing. its a working prototype, which seems to, well, kind of, work!
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