Condensation and Dobsonians

[Aidan]

greetings all,

is there any best way of dealing with dew/condensation on mirrors and eye pieces.

Significant dew buildup on the finder scope and main mirror of the dobsonian over the space of 4 hours.

hints or pointers appreciated for drying and preventing it happening again

Aidan

[big_dav_2001]

I asked the same thing a while ago an was directed to this article:

http://www.iceinspace.com.au/63-400-0-0-1-0.html

This gets the air flowing across the primary mirror surface and prevents dew without having to use heaters to bring the mirror temp up above the ambient temp and thus introduce unwanted thermal currents.

I tried it and haven't had a single drop of dew since. Although Im using a solid-tube, not sure if it's effective with a collapsible.

Here's my original thread:
http://www.iceinspace.com.au/forum/showthread.php?t=76593

Hope it helps
Davin

[Aidan]

Thanks.

Having a read over the thread now.

Looks like it would be simple enough

Aidan

[iceman]

A fan is definitely the best way to keep moisture/dew off the mirror. Works a treat.

[Aidan]

Thanks will follow up with Davin's link.

I guess the next is trying to keep finder scopes dry, may have to stop being lazy and keep lens covers etc on when not actively searching....

First really cold night with high humidity for the scope good to have a few little bugs, it makes me nerous when things work too well.

Aidan

[Poita]

I made a tube to slip over the ojective end of the finder-scope, about 20cm long, and it never fogs up any more.

[Aidan]

What did you make the tube from?

[barx1963]

I just ripped the bum out of an old stubby holder! The prob I found especially with a right angle finder was that the eyepiece still fogged up. Ended up attaching a .965" Kendrick eyepiece heater once I obtained a Dew controller setup.

Malcolm

[Aidan]

Cheers,

that works out well i have two old ones i keep for sentimental reasons, but was not sure what to do with them.

Hopefully clear skies tonight to test it.

Aidan

[Aidan]

Stubby holder worked a treat in high humidity... Thanks for the advice, the fan may have wait due to time and money constraints.