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Scope protection inside a roll roof shed
Just finished building a (very)small roll roof shed for my Celestar 8.
Is there anything other than a dust shield that I will need to protect the scope? I searched through newsgroups and on the web but everyone allways only seems to talk about portable scopes. I was wondering about dew or excess moisture. The temps here vary from -43F 2 weeks ago to +35 this week for winter temps to as high as +95F in the summer. Thanks in advance for any advice Dean C. |
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On Mon, 07 Feb 2005 05:41:21 GMT, Dean Crandlemire wrote:
Just finished building a (very)small roll roof shed for my Celestar 8. Is there anything other than a dust shield that I will need to protect the scope? I searched through newsgroups and on the web but everyone allways only seems to talk about portable scopes. I was wondering about dew or excess moisture. The temps here vary from -43F 2 weeks ago to +35 this week for winter temps to as high as +95F in the summer. Thanks in advance for any advice Dean C. Temperature isn't a problem, as long as you don't power up the scope when it's very hot. You shouldn't have dew inside the observatory, but watch out for dripping condensation from the roof if you have high humidity where you are. I wouldn't cover the scope with anything waterproof- if moisture is a problem, use something that is moderately water resistant, but which still breathes. _________________________________________________ Chris L Peterson Cloudbait Observatory http://www.cloudbait.com |
#3
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I rather think temperature is *everything*. An insulation jacket might
be a good idea. :-) The mass of the telescope and mounting lags behind when temperatures rise. Causing heavy condensation on every surface. If you take a cold scope indoors it does gets wet from condensation. But it dries out more quickly indoors because of the higher temperature and usual dryness of the indoor air. In an outdoor building everything stays wet much longer. No idea if this affects modern telescopes for good or ill. Hopefully a properly designed telescope can cope with constant wetting. I note that my 40 year-old equatorial mountings, which live constantly outdoors under small tarpaulins, age rapidly and need regular repainting. I even had to change the original steel shafts for stainless steel to stop them from rusting solid. Unprotected metal and tools in my unheated sheds all rust rapidly. Just in case this seems unnecessarily pessimistic, I'm all for having telescopes at the ready. Anything that reduces set-up time is time spent using the telescope. Just be sure your security is well thought out. http://mysite.wanadoo-members.co.uk/...k4/index.jhtml Chris.B |
#4
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We have very variable temperatures and humidity in the UK too. I want
my scope to be available for instant use too (which it is), and the gap in the eaves, between the roll-off roof and the walls, serves to keep the scope at ambient temperature at all times. Plenty of circulation. When it's not in use, I keep the scope covered with a loose blanket to fend off dust. However, as another poster mentioned, there is a lag before the scope reaches ambient temperature. Nothing that affects use of the scope at all (i.e. it doesn't cause detectable tube currents), but it can cause condensation problems. This is illustrated (on my scope) by opening the door in the morning after a very cold night. The scope is cooler than the (warming) morning air, and I can watch dew forming on the bare metal parts before my very eyes (as the "warmer" air rushes in through the door). Solution: a frost heater! Yep, I thought heat would be a complete no no in the Zerba Tree, but a simple, low wattage heat tube just keeps things that degree or two above ambient and keeps the damp away. It doesn't get warm at all (because of the aforementioned air gap and circulation) and I have noticed no "cool-down" artefacts as a result. I have noticed that things are much less damp though. So - if you have a permanent power supply out there, I'd say a small frost heater would be a good investment (they're very cheap to run too). Cheers Beats |
#6
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Dean Crandlemire ) wrote:
Just finished building a (very)small roll roof shed for my Celestar 8. Is there anything other than a dust shield that I will need to protect the scope? I searched through newsgroups and on the web but everyone allways only seems to talk about portable scopes. I was wondering about dew or excess moisture. The temps here vary from -43F 2 weeks ago to +35 this week for winter temps to as high as +95F in the summer. Thanks in advance for any advice Dean C. I use a cotton double-bed sheet sewn into a bag (soft, bug and dust cover, slightly water absorptive) and on top of that a bag made from 2 survival blankets suck together with aluminium tape (helps keep heat out on summer days and waterproof). Under this next to scope is 0.5kg of silica gel changed every week. Been like that for a few years and no rust etc, all nice and snug. See http://www.linnhe.net/observatory/index.html. Mark -- www.linnhe.net - Linnhe Observatory in the Highlands of Scotland |
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