The observer blues

[engaaraa]

After missing the November star party, spending the December new moon alone on the roof of a resort with a small borrowed telescope (the rest of the family was tired and went to sleep early) my relative bad luck with clear skies continued now in January with another cloudy and dewey night. We did enjoy looking at the usual winter bright objects, but I'm still looking for that perfect night of galaxy hunting.

So that brings me to the question of the effects of dew. What is the correct maintainance procedure when packing to go home in the morning with all the drenched equipment?

Specifically:
The shroud
The finder
The binoculars
The telrad
The eyepieces
The filters

[Dingo1]

As soon as you get everything home.  Dry and lightly oil all metal parts.  Use a lens cleaning cloth on all opticals.  Do this outside in your garage so the ambiant temperature is the same as outdoors.  (this prevents fogging)  leave the eyepiece out of the scope.  I find it safe to lay a dust free cloth over the eyepiece hole so air and moisture can escape.  Level your scope, so that neither end is higher than the other.  This helps prevent the development of residue on the inside of the lenses and mirrors from moisture and other air pollutants

[skyejim]

I never use any cleaning cloths or fluids until I've allowed the dew to evaporate off the lens surfaces - but I have such minor dew issues where I observe that I  can often clear a lens surface, even on a big Nagler or a finder scope, simply by holding the eyepiece in my bare hand and allowing a little bit of heat transfer to occur.  That will work if temps aren't a whole lot below dewpoint and the dew isn't too heavy - the moisture just magically disappears as the lens surface warms slightly.

 You do have to be aware that other deposits can accompany the moisture - any dust suspended in the air can settle as well, so keep that in mind when cleaning the optical surfaces after they have dried. There are potentially abrasive particles present, so blow and lend brush off prior to using cloths or cleaning fluids.

IF I can't dry optics when I knock down my scopes at the observing site, I leave dust caps off my eyepieces and just store them in their foam cutouts in my eyepiece case.  When I get things home, I open up the case and allow things to dry out overnight.  This has always been sufficient for the minor dewing I encounter - but in your tropical humidity, I don't know if this would suffice.  Maybe you need something like a 12 volt heat gun, judiciously applied to help things along...

Engaarraa, I'm lucky to seldom have to deal with serious dewing issues here in the dry southwest U.S. , so there are doubtless tricks I don't know about.  You might want to consider an anti-dew system like a Kendrick.  It can prevent dewing on eyepieces, finders, Telrads, and secondary mirrors through gentle heating - just enough to hold the optics above dewpoint.  Can't remember whether you got the secondary heater on your Protostar or not - I have one and it works using the Kendrick dew controller.  I've had two occasions wherer I needed to use it, and it worked superbly.  I use it quite often on my Nexstar 11 - SCT corrector plates are dew magnets!

Jim

[engaaraa]

Hey, thanks guys.
My holder does not have the heater, but I find I don't get dew on either mirror. I managed to keep the dew out of the eyepieces by not exposing the ones I was not using, keeping them in the car ready to use, but shielded. Any dew that formed on the one  I was using dissapeared inside the car after a while. But I left one by the scope and it was drenched.

The finder and binoculars got the worst of it. Simply drenched in water. I find them hard to protect without their covers, so I'm forced to cover them wet for the trip home. I figured this was bad, so that's why I asked.

Oh, and the filters seem to work like little dew magnets.

This does not happen every time, this is actually my second deweing. Yet , I figure the next few outings will be dewey because of the coldish season.

Lens tissue is the thin paper used to clean cameras, right?
I figure I will need a lot of it, they are very small....

[Dingo1]

Go to a camera store to get lens cloths.  Do not get them at Walmart or other discount stores.  You do get what you pay for.

Concidering I live in the heart of the wet snow belt, have had lot's of experience with condensation...JIm you are sooooo lucky.

As it is your finder and Binoculars getting the worst of it, as well as your filters, the lens cloths will really be a help there.  They are not paper, but feel like it, but are made of a paper linen combo.  Very lint free> I use it for all of my optics

[skyejim]

Yeah, filters definitely dew up easily if exposed to the sky - lots of glass surface attached to a very small amount of aluminum.  The lose heat quickly.  I keep mine in the boxes unless actually using them - and I try to be very conscious of not exhaling toward the filter and eyepiece as I screw them together.  If I accidentally fog a filter exhaling, I wrap thumb and forefinger around the outside of the filter cell, trying to create as much contact area as possible.  The heat from my hand conducts very quickly through the aluminum and will clear the fog in a minute or less.  Waving it around to get some air movement over the glass can speed this up.

I usually am able to get away with just partially closing the lid on my eyepiece case to minimize heat loss.  The kind of severe dewing you are runing into on your finder sort of cries out for a dew heater.  Probably the same for your Telrad if you've got one.  Keeping the eyepieces in the car sounds prudent, although that can be unattractive if you have to set up a fair distance from the vehicle.

Lens tissue!  Even I use reams.  Doing lens cleaning with a tissue, remember that you are picking up stuff with every stroke, and use each area of a tissue only ONCE.  A sort of rolling-back motion of the hand while moving it across the lens, that moves new tissue into contact and lifts  it away after it has cleaned, can minimize sleeks from inadvertantly dragging a tiny bit of dust over your coatings.

I personally like the Kodak stuff.  There are some tissues that are not terribly soft - almost like a waxed paper consistency - sold through places like Rite Aid  drug stores around here and they are to be avoided like the plague!  A good lens (not "lend" like I typed up above, can't correct a posting if you can't log in...) brush is essential, step two after using a blow bulb.

Jim

[Dingo1]

I have a wooden cigar box, with a small compartment that I have bags of silicon (you find them in electroncis stores) that helps with storage, as the bags of silicon absorb moisture.  This is for my filters and lenses.

[jacaranda3739]

I saw a website awhile back where they were selling aperture covers for sct's with those little silicon bags fastened inside.
I may try this myself, being that I have a project comming up where I will be using alot of tape. I will probably have some left over to tape the little silicon bags to my cover.