Condensation on scopes brought indoors

[omega3]

Last night was very cold. When I brought my scopes indoors, there was condensation on the refractor objective and the dob mirror. For the refractor, I left the cover off, and for the dob, I put the OTA horizontal with the cover off overnight.

The eyepieces also had condensation.

What is the best way to cope with this problem, for those who do not want to put their scopes in the garage?

Alan

[NGC 1502]

Hi Alan. What works for me :

Newtonian reflector - shower cap on each end, plug in focuser, place scope in

an unheated room overnight. You can wipe down the exterior of the tube perhaps,

but leave the caps on.

Refractor - caps on, place in storage box, place in unheated room overnight.

In the morning, check for condensation, often there is none, but if there is,

leave uncapped to dry out completely.

If you bring a cold uncapped scope indoors, the optics will become wet with

condensation. I realise not everyone has an unheated room to store stuff.

Storing scopes that way also means less cool down time when setting up.

Hope this is of some help, Ed.

[malc-c]

What issues can happen if we don't have an un-heated room. I brought my scope in last night and left it in the bedroom with the cover off for a few hours (until the tube was dry) before putting it away in a cupboard. Now you have me worried that I may be causing some damage ?

[brantuk]

It won't usually damage it but may leave smears on the optics where moisture has dried up. I allways tilt my dob downwars a little so any condensation that gathers will drip out of the end rather than onto a mirror or lens.

Acid rain however may cause damage to coatings if allowed to dry out on a mirror or lense. I leave caps off to get the air circulating and dry it out.

[NGC 1502]

What issues can happen if we don't have an un-heated room.

Well I wouldn't worry too much. But if you bring cold equipment

into a warm house, it will dew up. If your only choice is a warm

room, then it's even more important to cap it first to reduce

condensation on the optics as much as poss.

In the morning, when the scope has fully reached indoor temp,

uncap and dry out completely. Just do the best you can according

to circumstances, and relax.

Best regards, Ed.

[malc-c]

Thanks guys - must admit that on Wednesday evening it was dueing up before I brought it back inside !

[michael.h.f.wilkinson]

In my experience dew does not leave smears (unless you start wiping it). The main issue is that leaving the scope uncapped gets dust on the lens/mirrors. Generally if I leave the scope uncapped for say 30 minutes, this allows dew to clear from the corrector plate or objective completely (a central-heated house tends to be very dry). Very rarely do I see some motes of dust after that time, which I remove by blowing with a little bellows/brush for cleaning photographic kit. I also chuck in any spare silica gel packets I find in packaging into the telescope box to ensure any remaining moisture is removed. Moisture in the optics can cause build up of fungus, which eats up the coatings.