Whoa, hold on there Chuck. I'm not on a dew chaser project. That was only discussed as something some people were talking about doing at the ATM sessions. There are some web articles that Jay referenced a while back that discussed dew zappers in detail. Most of those were plans for the heating element, you still need to make/buy a controller. While dew zappers are good ideas, for our mostly dry Utah air, I feel that passive dew prevention is mostly enough. Then again, I don't own a SCT or other design that have large corrector plates at the front. Those are really prone to loosing heat fast and dewing up. A large dew cap would be my first choice on those type of telescopes. Then if they still dew up, go on to more aggressive measures. Mat -----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Chuck Hards Sent: Monday, November 07, 2011 8:12 PM To: Utah Astronomy Subject: [Utah-astronomy] Dew/Frost prevention OK, my word isn't good enough, so here's an explanation written in nerdese: http://home.comcast.net/~astrophoto/Articles/Dew.htm It's on the Web, so it MUST be true. All you have to do is warm the optics above the dew point. That temperature varies dependant on humidity. You don't need "warm" optics to prevent dew or frost. In most cases, the optics are still cool to the touch. Mat is on the right track with his dew chaser project. Those of you who are in need should seriously consider attending his next ATM session. A properly designed dew chaser won't consume a lot of current, but will add hours to your observing/imaging sessions when the relative humidity is high. When my work schedule allows, I'll search the S&T archives for some articles they've printed over the years on active and passive dew/frost prevention. I think I get a few days off in late December. :-( _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php ---------------------------------------------------------------------------- This message and any included attachments are from Siemens Medical Solutions and are intended only for the addressee(s). The information contained herein may include trade secrets or privileged or otherwise confidential information. Unauthorized review, forwarding, printing, copying, distributing, or using such information is strictly prohibited and may be unlawful. If you received this message in error, or have reason to believe you are not authorized to receive it, please promptly delete this message and notify the sender by e-mail with a copy to Central.SecurityOffice@siemens.com Thank you