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Kendrick dew protector

Started by ddoctor, 09/12/2003 10:33AM
Posted 09/12/2003 10:33AM Opening Post
Thanks John. So you think it won't help then to use the strap on the outside of the tube for this particular scope?
Posted 09/12/2003 11:08AM #1
In order to prevent dew formation, you need to keep the
optical surfaces just slightly above ambient
temperature. You also need to trade this off
against having so much heat so as to cause heat
plumes and air currents which will degrade the images.

The best approach for a Newt would be to
apply a small amount of heat to the back side
of the mirrors (especially the secondary mirror).

You might be able to get some reduction in dewing
by placing the dew strap around the outside of the
tube just below the secondary mirror. Maybe the
radiated heat will help a little bit to keep the
secondary dry. But the potential for causing
heat plumes will be pretty large, and any heating
of the secondary will be slight.

Maybe the thing to do is try it and see what happens.
If you are mostly looking at deepsky stuff
(vs. planets) perhaps it would be OK.