Help with dew??

[ericc]

Hi all,I am just starting to find out about the joys of early morning dew(I was up at 2am this morning and the dew struck at around 3.30)!!!
Can anyone tell me the best way to keep dew from the finder scope objective??
Thanx in advance!
By the way,Im having a ball with the new Bintel dob,I get out the back yard viewing every possible chance I can--one very happy camper!
:thumbsup:
Cheers--Eric

[sheeny]

There are probably three tactics you can use against dew.

Shield the objective... so you could make a longer dew shield to extend the tube further out and this will shield the objective from more of the sky so it doesn't lose so much radiant heat and it helps to keep the air new the objective there and at the same temperature.

Use a dew heater. This would require a substantial battery and preferably a controller for your dew heater. Have a look in the Projects and Articles section. I've written a couple of articles about building your own dew heater controller and making your own dew heaters from resistors if you want to save a few dollars and DIY.

The last tactic I can think of is to use a 12V hair dryer (and of course a battery) You would only use the hair dryer to clear the lens once it has fogged before you need to use it. This is probably not the most efficient way to go, but some of us have to use all three of the methods!

Al.

[Paddy]

I always keep the caps on and remove them each time I want to use it. Or a small plastic bag to cover it between searching for targets (this is what I do with my Rigel red light finder)

[seanliddelow]

My tatic is to go on a cemented surface like a driveway- Then you shouldnt have a problem.

[RAJAH235]

Eric...
These old threads may help...
> http://www.iceinspace.com.au/forum/showthread.php?t=1640
> http://www.iceinspace.com.au/forum/attachment_browse.php?a=6091
> http://www.iceinspace.com.au/forum/attachment.php?attachmentid=1484
Mine is still going with absolutely no maintenance req'd at all.

I used a similar set-up for my "equipment/eyepiece" box.
> http://www.iceinspace.com.au/forum/attachment_browse.php?a=6090
Just use an "On/Off" switch.

The heaters & my Magellan 1, run all night off a 12 Volt 7 AH Gel-cell.

[jjjnettie]

Cut the bottom off a stubbie cooler, the wet suit type. It's the ideal size to slip over the objective of your finder. Let it over hang an inch or two.
Of course on really dewy nights, you'll have to pull out the hair dryer now and then.

[ericc]

Thats exactly what I did Jeanette--stubbie holder(and I thought it was such an original and clever invention, on my part)!
Hey it works so far for me!
A couple of nights ago the finder occular end played up and one ep did the same--hmmmmm--I suspect I will be using some of the other ideas here also?I bought a telrad(which is such a fantastic thing to use)and very quickly added the plastic dew shield!
The hair dryer seems like a good idea,does anyone know of any 240v or 12v quiet models for 3am antifogging--as the neighbours may assemble a lynch mob?
Thanks for the ideas--keep them coming as Im all eyes and ears!!!
Cheers-eric

[RAJAH235]

Eric,
I found a good place for 12 Volt hair dryers is.....
A boating/marine store.
Got to keep the hair looking nice 'n shiny after a day in the water now, haven't we? ;)