From: Alan Friedman <alan@greatarrow.com>

Date: November 29, 2007 7:37:01 AM MST

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] Raising a heat issue

ps -

At a long EFL, body heat is certainly an issue around the scope in very cold conditions. My 10" has a removeable back plate that exposes the mirror to the surrounding air - it works nicely to help shed heat but adds to thermal distortion when I bring my had close to adjust the focus (which I do often). I always put the cover back on when I start to image. I guess a motorized focuser would be helpful to keep body parts away from the telescope...

Alan

On Nov 29, 2007, at 9:27 AM, Alan Friedman wrote:

Hi -

If I have my 10" scope out for a long evening of observing at a rural star party and dew promises to be an issue I will set a heat strap on the dewshield at low so that I don't get shut out early. But I am loathe to do this at home if the seeing is promising for high resolution imaging. Much of my work is done in the hours before dawn - for this I set the telescope out the night before (I store it in an unheated location) with the cover on and a tarp over it. When I get started, I place a 1/2 foam blanket around the dewshield and extending out beyond it by several inches (the dewshield is about 12" long itself) - this small bit of insulation seems to be enough to forestall the onset of dew during an hour or two of imaging in the pre-dawn hours. 

best,

Alan

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