moisture buildup in scope

[northcanadian]

Hi all:

A while back I had quite a bit of moisture buildup inside my 9.25 sct (mirror fogged up and noticed a couple of water droplets inside tube).  I store the scope outside in an observatory/shed. Over the past year whenever I had dewing I would use a hair dryer to get the dew off the corrector.  I think over a period of time doing this a fair bit of moisture built up inside the scope.

Its fairly cold right now, but when it warms up somewhat my plan is to bring the scope inside for a few days....hopefully drying it out completely. Will this work?

Does anyone else have this happen?

Thanks

Cheers

Roger

[Tinker1947]

I fitted on of these and changed the gel sachets as soon as they went Green (roughly weekly) My C11 had quiet a bit but over a couple of weeks it cleared the scope was left in a Obby 24/7 with no heat....

http://www.firstlightoptics.com/dew-prevention/flo-125-2-inch-desiccant-cap.html

[ronin]

That will dry it out to a fair extent but I suspect that you really need to circulate some air around the scope internals, more a don't expect too much from evaporation alone  as it still has to go somewhere.

Not sure if they are available to you but FLO (I think) have some of the eyepiece bungs that arte machined to have holes ih them and you drop bags of silica gel in. This slowly absorbs moisture present.

If none then I suppose you could make something along the same lines.

[northcanadian]

Thanks for your inputs.  I checked and don't think I can get something like that here.  Perhaps I could adapt an old cheap eyepiece .  I will also look into some kind of air circulation rig. 

Much appreciated

Roger

[Tinker1947]

35mm film can is about the right size......

[Alkaid]

Perhaps make sure that the eyepiece end is "up" so that any evaporating moisture will rise up and out when you start the drying process? Just an idea, I'm not 100% sure how effective this might be, but suppose that physics dictates that warm air will rise. Wish you the best of luck with the job.

[jambouk]

I wonder if being eyepiece end up is the best position, given the long tube inside the scope?

James

[moriniboy]

This is my solution

2" to 1.25" adapter

1.25" aluminium plug

Clear bolt bottle which fits inside the 2" end of the adapter with holes drilled in bottom (silicon or Araldited in)

Breathable foam internally

Color change silica gel

You can see that the beads need drying out on the photo as they should be orange.

[kev]

This is why, after drying internally i point a COLD hair dryer down the tube, so as to displace the moist air.

Sent from my iPhone so excuse the typos!

[sungazer]

Hi , In the 1960s I used a 12 volt bulb of about 10 watts under the tube unit and a cover over, but not under, the scope in the observatory this supplies enough warmth to avoid condensation in the optics. This then kept the unit about 1 degree above the dew point, and needed very little cool down time. Hope this may be of use with the problem. John.

[cathalferris]

A long tee shaped piece of cardboard, long enough to reach through the baffle tube but not touching the secondary, will allow a circulation to take place especially if you can point e.g. a pc case fan at one side of the tee on the eyepiece side. The card will divide the tube into an up and a down channel for air to move, taking moisture with it.

The "cat cooler" devices do pretty much the same thing.

Just warming up the scope will not be enough to remove moisture - it'll simply put that moisture into the air in the scope. You'll have to ensure that there are full exchanges of the air entrained within the scope.

Sent from my GT-I9295 using Tapatalk

[cathalferris]

Just thinking, if you try and copy the design of the Lymax Cat cooler (http://www.lymax.com/sct/ ) that would help a lot. Air not being directed at the secondary would be a good idea!. An easy way of doing that would be to turn up the end of the card insert where the air is descending, forcing the incoming airstream to the side of the OTA

[faulksy]

Starlight/feathertouch do one I bought one for my sips system.have a look on there site something like moisture obsorbing bung

sent from my fone using fingers

[RT65CB-SWL]

Hi Roger,

As per 'Tinker1947'. I too use empty 35mm film canisters, (just drill a few small few in the base of the canister), add a couple of desiccant gel sachets in them and pop in my 'scopes eyepiece holder.