Quote:
Originally Posted by Wavytone
Carbon fibre isn't much better as it is thermally conductive - and black.
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Ooooh.... careful there.
Whilst carbon is an exceptional thermal conductor, the resin that it is embedded in is an exceptionally
poor thermal conductor.
The thermal properties of carbon fibre tubes, therefore, are not uniform.
Aligned with the direction of the weave, the thermal conductivity is a couple of percent that of aluminium. Perpendicular to it, the figure is even less (by a factor of 10).
I suspect the angst directed to carbon fibre is based on assumptions rather than direct measurement.
fwiw) Professional observatories take a completely different approach to thermal management. They pre-chill the telescope prior to an observing session... as long as you are above dew point when the dome is opened, you're good to go. Cold primary mirrors do not induce a turbulent boundary layer.
As to seeing objects smaller than Dawes limit, etc)... you don't need to resolve an object in order to perceive a contrast minima (or maxima).
Much like you don't need to resolve a star in order to see it.
best
~c