What do you guys use for dew control?

[shirox]

That depends if you are getting the yellow pack or the pink pack from winter time.
Yellow ones are bigger and definately better. I usually use a minimum of 2 each for my twin borgs. For bigger ones, you can use more and even if u use 8, its only $2 haha.
So far so good for refractors. As gary mentioned, perhaps for bigger aperture like 8" Cat you might wanna experiment between the winter and daisos

[Gary]

The Daiso packs I have been using is the yellow one shown the following pic:

http://1.bp.blogspot.com/-Oc9y2aPUlFI/T ... .08.18.png
Image Credit: http://invisibleloner.blogspot.sg/2012/ ... -lieu.html

Have not tried the Daiso pink sheep version before. Perhaps they are better.

For my C8, I use about 4 big packs (Winter Time). Perhaps my C8 astrozap dew shield is too thick and need warmer heat packs.

[mymoon]

Thanks.

Errrr how do you use them . Pardon this country cousin but would appreciate a picture in use.

Thank you.

[Gary]

Hi mymoon.

Here's how I do it:

- Take the heat packs out of their packaging
- Shake them for about 10 seconds to let the powder mix around inside and get warm
- Attach them *near* the corrector or lens or exposed glass surface. Some of these heat packs have built-in adhesive on one side. I prefer those without and just secure them with army helmet rubber band which can be purchased from your local army supplies store.

In the following pic, the white packets are the heat packs secured by a black army helmet rubber band after putting on the dew shield for my C8.

(Image Credit: Davegn)

[starfinder]

Hmmm... I wonder, is there a particular reason for putting the heat packs over the dew shield? Is it a tight fit, or to prevent overheating?

I usually put them *under* the dew shield of my SCT, so that the shield insulates the packs from the air and the heat gets radiated downwards into the OTA's corrector plate.

For my 120mm refractor, I bought a 'leg warmer' cloth from Daiso (guess how much it cost) which is like a sock with both ends open. I leave it on the tube near the lens / dew shield and store a heat pack underneath for ready usage. See photo here:
viewtopic.php?f=5&t=11843

[shirox]

That may be the reason u feel that its not hot enough. U should put the packs in direct contact to the telescope. Metal are better heat conductor than dew shield which is of pvc? Haha

[Gary]

Hmmm... I wonder, is there a particular reason for putting the heat packs over the dew shield? Is it a tight fit, or to prevent overheating?

I usually put them *under* the dew shield of my SCT, so that the shield insulates the packs from the air and the heat gets radiated downwards into the OTA's corrector plate.

For my 120mm refractor, I bought a 'leg warmer' cloth from Daiso (guess how much it cost) which is like a sock with both ends open. I leave it on the tube near the lens / dew shield and store a heat pack underneath for ready usage. See photo here:
viewtopic.php?f=5&t=11843

The Astozap dew shield is specifically designed for the 8 inch with a notch at the bottom for the long dovetail. It is quite a tight fit but I will try squeezing in some smaller heat packs underneath and securing the dew shield over them with the rubber band.

Also partly concerned about overheating as for dew control, only need to raise the temperature of the corrector *slightly* above dew point. Too much heat transferred may affect the performance of the optics and thus drawing a potential wrong conclusion that the seeing condition for a particular night is poor when in reality it may not be. A bone dry corrector by itself alone is not the only and final conclusive indication that the right amount of heating has been applied.

So far have tried this setup in a few relatively dewy places and it seems to work well - observing for the whole night without the corrector dewing up. So just thought if it aint broke don't fix it. But will give your suggestions a try since it will be a fun learning experience how much heat is too much or too little and where is the best place to attach them for a particular brand and size of heat packs.

Thanks for the leg warmer suggestion. May give that a try on my refractor.

[mymoon]

Thanks Gary.

Cannot get in Malaysia these one use throw away chemical warmers

From the url the longest available is 18 hours.

Malaysia available only the reusable ones.

Cheers

[Gary]

Hi mymoon. You are welcomed.

Came across this Winter Time sales Malaysian ad:
http://www.mysales.com.my/winter-time-a ... -sale-1636

There is also Daiso in Malaysia:
http://www.aeonretail.com.my/daiso/

Perhaps you can to check with these stores if they carry such heat packs.

[mymoon]

Phenomenal! Thanks Gary.

I will certainly try the listed shops.

No more excuse of being dewed out.

Cheers