reflector cool down

[Rob63]

Now that the evenings are getting a bit colder and dew is rearing it's soggy head, how do you cool down your scope (I have 8" Dob)?

In summer, I normally take the end cap off and have the tube vertical for 1/2 hour or so before observing but surely in winter this runs the risk of water drops forming and  running down and hitting the mirror ?

Do you leave the end cap off and have the scope horizontal or will it cool down just as well with the cap on?

[Peter Drew]

I would angle it at 45 degrees upwards with the cap off. 

[Bart]

i position it on the horizontal wth cap off. careful the wind doesnt catch it and swing it all over the place. you can start looking at the odd galaxy or nebula for the first 20-30 mins as collimation doesnt need to be spot on for those, unless you're trying to tease out some real detail.

Barry

[swamp thing]

I don't bother waiting for cool down. I start observing straight away. It makes little difference on low resolution objects like nebulae and Galaxies. I don't observe planets.

[LeeB]

I keep it in the fridge  , no sorry, as above , I like to leave it just pointing  a little up from horizontal with the cap , stops the rain!!! just in case.

[Moonshane]

like Steve I pretty much start observing as soon as the scope is out, collimated and I have a brew. as time goes by the images get sharper and cleaner and unlike Steve I do observe planets and if I am that night, then switch to higher powers as the conditions and available objects allow.

[Moonshane]

ps, when not using the scope (e.g. if I want another brew) I leave the scope at about 45 degrees as above.

[AlexB67]

I do the same, start more or less straight away, but my scope has a short cooling time, an then images get better and I up the power often as the session goes. Interestingly, I found when I am near a wall or obstruction in my garden and looking at the out of focus airy disk even sometimes after 20 minutes I still get some hefty tube currents on occasion, anything where there may be a temperature difference perhaps, this may not helping.  It shows how sensitive these things are. Oh I should say it is not blocking the view obviously, that causes some interesting things as well 

Steve, how could you miss out on such wondrous beauties  and not look at planets, but you do,  you just doesn't realise it, You look at one every day

[Andyj]

I have a supplementary question to this, particularly directed at those in more northerly locations I suspect. As Finnish winter sees temperatures regularly drop below -20°C, I wondered about storage of my telescope outdoors, should I eventually be in a position to find a solution for doing this. What sort of low temperatures can a telescope such as mine (see below) tolerate? If I wanted to construct something outside for it, would I be in need of some basic heating? I appreciate this is perhaps a "rooky" question.

[Laurie61]

I have a supplementary question to this, particularly directed at those in more northerly locations I suspect. As Finnish winter sees temperatures regularly drop below -20°C, I wondered about storage of my telescope outdoors, should I eventually be in a position to find a solution for doing this. What sort of low temperatures can a telescope such as mine (see below) tolerate? If I wanted to construct something outside for it, would I be in need of some basic heating? I appreciate this is perhaps a "rooky" question.

Ideally you would keep the scope out of a heated home. I keep mine in an outbuilding and have a dehumidifier to keep the worst of the damp out through the winter, I don't use heating. The closer the scope is to outside ambient temps the better.  I have no experience of -20 dg C but would think that some of the lubrication used on scopes and mounts would be getting a bit stiff?  

[LukeSkywatcher]

I have to agree with others who say they never wait for their scopes to cool down. I own refractors (no cool down time needed really), I own a Dob and i own an SCT.

Ive just always started observing from the moment i go out and let the views improve.

[Gomtuu]

i position it on the horizontal wth cap off. careful the wind doesnt catch it and swing it all over the place. you can start looking at the odd galaxy or nebula for the first 20-30 mins as collimation doesnt need to be spot on for those, unless you're trying to tease out some real detail.

Barry

As I have to drive to observing sites, I normally leave it horizontal, with cap off, on a blanket while I'm aligniing the mount. By the time I'm polar aligned, it's already cool enough!