|
I know it is obvious that my refractor (White) collects less dew than my SCT (Black) and the refractor before it (Also black)
What would be an advantage in carbon fibre would be the thermal expansion aspect in the SCT. With two magnifying mirrors in the SCT design the shift of the focal plane as the mirrors are moved relative to each other is something like 25 X the change in distance between the mirrors. In practice the aluminium tube C925 shifts focus by hundreds of microns per degree of temperature change. If a carbon tube cut the thermal expansion rate of the tube in half that would be a pretty big advantage. And if cooling and gathering dew is a concern, loose the sexy carbon weave look (If it has been laid up well enough to look good) and paint it white.
I can say the SCT certainly changes focus rapidly, I set up my refractor on Monday night but I didn't bother with the SCT as the night was expected to cool by around 10 degrees, the SCT would be catching up to the temperature change for at least half the night. I know with a temperature gradient like that it can go from sharp focus to doughnuts in 20 minutes. And you can't just trigger focus runs by temperature change as the tube lags the air temperature. I end up with it doing 5 subs and a focus run every third or fourth one in order to keep it sharp.
|