One kilogram is 2.2 pounds I believe. And I think a GSO 12" F/5 newt has a weight of 15kg => somewhere around 33 pounds. Keep in mind that you are dealing with a pretty large tube so the slightest breeze can make the tube move.
Back here in Europe we have the OTE150, a nice German EQ mount with a PE of +-5" (not sure though). It costs as much as a G11 but can handle 70 pounds visual and 55 photographical. A dealer puts 14" F/4 newts on it and sells them as "perfect" imaging platform. To bad it's as ugly as hell
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