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.

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

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

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

On 7 Feb 2005 00:00:49 -0800, wrote:

I rather think temperature is *everything*. An insulation jacket might
be a good idea. :-)

My primary observation about the temperature had to do with the
mechanics and electronics, which can tolerate a very wide range. At the
coldest temperatures grease can become nearly solid, and above about
100°F it's a good idea to make sure that electronics are off.

A properly designed observatory should maintain an inside temperature
close to the outside temperature. Any sort of insulation, either of the
observatory itself (unless the temperature is managed actively) or of
the telescope is likely only to make matters worse.

There is little reason that a telescope in an enclosed observatory
should have dew collecting on it. A telescope that is already dewed up
will normally dry on its own once the roof is closed. I've never had my
telescope form condensation inside the observatory in the morning as the
temperature rose. The scope surface temperature just doesn't lag that
far behind the ambient at normal, outside changing rates.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

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