Quote:
Originally Posted by glend
Cold in Brisbane?
What kind of scope is it? An open ended scope like a newt is much more likely to have this problem, and it is made worse if your using a cooled camera, as cold can transfer to the MPCC. A five inch heater strap wrapped around the focuser tube could help but humidity is your big problem. It's less of a problem in an observatory but if your on a tripod on the damp ground your going to be fighting it.
If the scope is a newt and you have a fan on the back this can help keep the air moving over the inter facing surface of the MPCC and may help keep it clear. Most good rear fans can be used while imaging (just mount them on silicon pads if possible and use one with a good bearing). Use a long dew shield on the front if you can (assming its open), this will slow it down. If it is an open truss type scope, even with a shroud, this will be an ongoing challenge. I have heard of people using small plastic scroll fans to push air across mirrors (boundary layer movement) to keep fogging at bay, but you would need to be able to mount it somewhere out of the light path where it can blow across the MPCC lense, or into the focuser tube opening.
Good luck.
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Yeah. Cold. Believe it or not. Getting down to nearly 0 where I live.
It is an open ended newt. I don't have fans on the scope.
I just might give the dew shield a crack.
Plus the heater strap on the focuser.
Thanks for the thoughts Glen
Scott