Re: Eyepieces and cold weather observing.

Heat is more effective than non-heat methods; and to the best of my
knowledge and experience the small amounts of heat needed will have no
adverse effects on image quality.

On nights when condensation is expected to be a problem I keep all
eyepieces other than one I'm looking through capped and inside a
closed box. This keeps them condensation-free -- at least until
they're taken out and used ;-)

Usually (but not always) heat from my eye and/or face is sufficient to
keep the eyepiece that's being used free from condensation. (Facial
hair *might* play a role in the success of this method -- perhaps by
trapping moisture before it can reach the eyepiece's eye lens.) If I
leave the scope for any length of time I cap the eyepiece.

The above simple and inexpensive measures work for me, in my semi-arid
climate, most of the time. Only when it becomes evident that the
above measures will not suffice do I break out a Kendrick eyepiece
heater -- a wrap-around heated collar. This 'last resort' method has
always worked for me. Unfortunately it's a solution that comes at a
price: the heating strip(s), a control unit, and a power supply.

Willie R. Meghar
Observational Notes at:
http://meghar.blogspot.com/
.

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