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Old 05-04-2021, 07:53 AM
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gregbradley
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Join Date: Feb 2006
Location: Sydney
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Aluminium tubes are best for APOs because the change of focus of the lens with temp changes is partially matched by the contraction of the alum tube.
Carbon fibre then is not recommended for APOs per AP's Roland Christen also because of thermal currents it can cause.

Carbon fibre on the RC and CDK I have works super well but then the issue is more the temp difference between ambient and mirror temps.

Greg.
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