Quote:
Originally Posted by Marke
I am positive - cf is an insulator so it takes a lot longer to equalise temp
as it will keep the inside of the tube at what ever temp it was left at for longer. Steel tube will transfer the heat much quicker reaching equalibrium
faster which is also why it changes focus more quickly . You can have one or the other.
Its why you dont see big refractors in CF either they would never cool down the inside air would be insulated even more .
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The reason why most to top end refractor manufacturers use aluminium, is that when the objective cools and moves the focus point inwards. Thus, a shrinking aluminium tube compensates somewhat for this effect as it also cools and shrinks.
Roland christens thought on the matter:
http://tech.groups.yahoo.com/group/ap-ug/message/55064
Also note that mr Christen uses carbon fibre on his cassegrain designs.
Brett