Years ago my 10" Parks mirror came packaged just as you described, with plastic wrap directly adhered to the aluminum surface. So, thinking that Parks wouldn't do anything to their mirror that would cause problems, I also stored it that way. Bad idea. My mirror has permanent marks on it, whether from out-gassing or some other process I couldn't say. The marks look a bit like streaks left from Windex. As near as I can tell the performance has never been compromised, but I am sorry that I marred the surface. BTW, the Parks mirror has been a fabulous investment - well-figured, very sharp images (even at high power) and a joy to use. Kim -----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Richard Tenney Sent: Monday, May 05, 2008 12:13 PM To: Utah Astronomy Subject: Re: [Utah-astronomy] Collimation of a Dobsonian This reminds me of a question I've been meaning to ask some of you experts. What seems like a simple solution to dust on primary mirrors -- a piece of saran wrap gently laid over the primary to act as a dust barrier when stored, I've been told is a really bad idea, as there is some kind of out-gassing of plastic compounds that interacts with the mirror surface, etc. Is this in fact true, and if so, it seems to me that some enterprising chemist could come up with the equivalent "plastic wrap" that would not have such a problem. Or is the problem something else (e.g., risk of scratching, etc.)? --- Chuck Hards <chuck.hards@gmail.com> wrote:
Saturday I met with Raeburn Kennard to examine his 10" Odyssey. The optics were remarkably clean for such an old telescope, so much so that a cleaning wasn't warranted. He is to be commended for taking such care to protect his optics. Also his collimation was so close that it came down to the utilitarian sink-trap focuser being the sole reason for any out-of-collimation condition. Again, remarkable to see a cardboard Dobsonian hold collimation so well, for so many years. Upgrading to a new, more precise focuser was discussed as an option.
Many veteran observers could take a lesson from the meticulous care Raeburn has obviously exercised with this telescope. The optical tube is essentially in new condition, even though he has used it extensively over the years. _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com
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