Coming in from the cold

[Keypix]

Hi

I was wondering whats the best way to store a scope after a cold & dewy evenings observation.

I have a SW200P and last night after an evening where dew was affecting my eyepieces a lot, i gave up after a while and brought the scope back inside.

Bringing the scope into the warmth obviously misted everything up even with the caps on and also misted up the primary mirror with a lot of condensation, so was wondering whats the best way to store it after a session for it to dry out. Should i leave all the pieces out with the caps off to let them dry out or is there a better way to stop the condensation? Would constant misting of the primary mirror damage it?

Many thanks

Kiran

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[cotterless45]

Just keep everything that's been dewed up in the warm. In a short time glass and metal will reach room temperature and the dew will be gone.

It'll be on there for only a short time. What affects mirrors is long periods of dew/ humidity. More likely to result in drying off marks and collecting dust than damage to coatings.

For extended use you could fit a dew heater to the primary. Normally if the air is that damp , seeing can deteriorate.

Hair drier use will also keep it at bay for a time. It's mainly autumn and spring when it's bad.

A camping mat dew shield also helps as does observing from a hard surface,

Nick.

[Mattscar]

I dont know if it helps at all, but what makes me feel better is leaving my scope on an ever so slight angle pointing downwards. That way should any liquid ever actually form on the inside (which I dont think it would but helps to be prepaired) it will collect in the caps rather than on the primary. Its more a psychological placebo for me than an actual solution

[astrorabbit]

I sort dewy eyepieces out with a camera dust blower. I use the Manfrotto rocket style one, couple of blasts and dewy optics be gone.

Last night was pretty bad here down south!

[hippie]

Just bring your gear in and let it dry naturally in the warm before putting lens caps on etc! & packing it away,   

[Langy]

Even though all my gear is stored in the open next to the stairs, the first thing I do as soon as I get back indoors is to make sure all surfaces are exposed to the much warmer air in the kitchen. All caps off everything that has been outside including EP's that were outside and not used. I usually lay the EP on it's side balanced on top of the caps so it can't roll away and then both ends are exposed to the warm air. My primary always gets condensation as soon as I take the scope indoors.

As soon as the equipment is clear of condensation it is covered up / packed away as required. All my small equipment is stored in a camera bag, my bins have their own case and the scope sits next to the stairs fully assembled but with the legs at the lowest height for ease of moving. I do have to keep the scope main dust cover off for quite some time to allow the condensation to properly clear, but I make sure the scope is horizontal just in case my kids decide to drop something where it shouldn't be.

Last night my bins were affected far more than any other item, they took absolutely ages for all the condensation to clear. Leaving these to naturally clear left them in a clean state.

The best comparison I could offer is when you get in the car first thing and the windows are all full of condensation. If you try to wipe them you end up with marks all over the windows. By letting the air of the vents clear the windows (which can take some time) the windows all stay nice and clean.

[RichM63]

As per the others^

Whatever you do, do not be tempted to wipe your mirror, this will wreck it faster than I can type this.

During observing I tend to keep my unused EPs in my various grit free body warmer pockets, keeps them nice and warm and dew free.

Rich

[Dolito]

As per the others^

Whatever you do, do not be tempted to wipe your mirror, this will wreck it faster than I can type this.

During observing I tend to keep my unused EPs in my various grit free body warmer pockets, keeps them nice and warm and dew free.

Rich

Do EPs not need a cool down like the main mirrors do? Is it better for them to be warmer?

[Andy Milner]

Hi all, I'm planning to use mine outside my summer house then store it in the summerhouse after use. I see everyone is am saying take it indoors to warm up. I take it it's ok to put caps in and store in summerhouse after use? Or if there is dew, use hair drier then cap them store back in summerhouse? Summer house has no gearing by the way.

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[todd8137]

Point the open end downwards leave the caps of for a hour ,put it in a room you not use in as in the kitchen or the room you in dust is every were floating around refrain from try in to clear the mist away

Pat

[Langy]

Hi all, I'm planning to use mine outside my summer house then store it in the summerhouse after use. I see everyone is am saying take it indoors to warm up. I take it it's ok to put caps in and store in summerhouse after use? Or if there is dew, use hair drier then cap them store back in summerhouse? Summer house has no gearing by the way.

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There are a lot of people who keep their equipment outside in a cooler location like garage or shed. If your scope is full of dew then you will need to make sure those areas have access to air so that they can clear. It may just be make sure the scope is point downwards and leave the caps off. Your summerhouse may well be too cold and still allow dew on the scope which may mean other options are required.

I'm far from an expert, maybe someone who stores their scope out of the house can help. There was a recent post in the beginners section on where do you keep your scope. Maybe look at that and see if there is anything in there about dew or contact an individual who stores theirs outside.

[RichM63]

Do EPs not need a cool down like the main mirrors do? Is it better for them to be warmer?

I find that I am far more likely to fog a cold EP with my breath than I do with a pocket stored EP.

In the same way that as a spectacle wearer, when I go back inside after a cold observing session my cold spec lenses instantly fog up.

I suppose it is a local climate thing.

Allowing the scope mirrors to cool before observing is not about dew prevention but is performance related to temperature differences between the mirror and the ambient air causing turbulence inside the scope and also the focal length will change as it cools to ambient temp.

Rich

[adavies8900]

I normally leave mine a the spare bedroom with the window open a little. If thats a good thing 

[Skipper Billy]

I was out for about 4 hours last night and after about 2 hours everything was dripping wet. Within the next half hour the dew all turned to frost and getting the gear inside was like carrying it across a skating rink.

I left it all spread out in the warm house and by this morning everything was bone dry and unmarked - the only thing that wasn't really affected was my laptop - I guess it has some internal warmth and air flow from the cooling fan.

The air temp when I went out was +2 and when I came back in it was -3.

I keep my ep's in  plastic box with foam cut to fit them and a small moisture magnet in the box - the crystals in the moisture magnet have earned their keep and now need replacing.

All my gear (except ep's) are stored in an unheated workshop so they are ready for action and already cooled down.

[Keypix]

Thanks for everyone's advice. As I suspected I'll have to leave everything laid out, caps off, to dry after a viewing session.

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[AstroAdam]

Yep - natural drying is the order of the day.  With a newt, putting the lens cap on when it's dewey isn;t so much of a problem, it'll just dry slower.  However, try not to do it for refractors, as they are much more likely to mould up eventually, as the air flow is much less behind the lens caps...

[AstroAdam]

One thing I will say is it's all vary scary when it first happens - it looks terrible!  Don;t fret though, its part and parcel of a scope's use.  My new Starwave was covered in frost when I brought it in the other morning...  They're built to take some of that sort of thing....

[baggywrinkle]

In Aus I kept my kit in an unheated building in the back yard. Never came to any harm and always adjusted quickly.

When we did get dewing conditions I just used to point the OTA downwards and let it dry naturaly.

Dew is eesentially pure water and as such should not leave a mark, BUT the air of course does contain dust and other nasties that get trapped in the dew so be careful if you do have to get rid of dry marks.

One of the worst areas would be near the sea where there is salt laden air.