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dew on newt primary
hi mike
Blowing air from the rear will help as others have said. Having an idea of the relative humidity on ths night and a temp sensor on the primary blank can also help you understand what is going on.
There were some fairly detailed articles on mirror fans in US S&T some years back. Blowing air across the front surface of the mirror may also help with preventing dew, and front fans do specifically help with preventing local seeing effects due to pooled warm air etc.
I assume this is in a cloeed steel tube? Is this to prevent dewing on the mirror while it is 'parked' in the wee hours or just while shooting? (the high humidity at the moment is a challenge)
Wrapping a dew heater strap around the mirror with a low pulse going through it might help here - an intelligent dew controller with a temp probe could also be a good option. Testing would be required to see if it would work positively while actually shooting with the scope.
I'm considering this as well as I'm milling a primary mirror cell for a mini 6"newt CF astrograph at the moment. It will be the first solid CF tube scope I have worked with so I'm not 100% sure how it will deal with dew etc. In its former timber tube, it never ever dewed up.
guy
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