Eyepieces fogging up.
Posted 28 November 2010 - 01:24 PM
I'm using 12" Lightbridge, TMB Planetary 8, generic 17mm 65fov.
The scope also has an Astrozap light shield, and secondary dew heater.
I'm setting up outdoors in sub freezing temps. I keep the scope and ep's in an unheated garage (about 10 degrees last week)
I set scope out for at least an hour b4 viewing. Is the fogging normal, or am I missing something to prevent it?
Any help appreciated.
Posted 28 November 2010 - 01:26 PM
Try keeping the eyepieces inside the house where it's warm and keeping them in your pockets when they aren't in the focuser. If the EPs stay warmer than the ambient air, they will fog/frost over less.
Posted 28 November 2010 - 01:27 PM
Posted 28 November 2010 - 02:01 PM
Posted 28 November 2010 - 02:11 PM
Eyepieces with tight eye relief, and binoculars, will fog up just because your eye is so close to them when viewing. These require that the eyepieces be kept warm before use and while in the focuser. You can get heater strips just the right size for your eyepieces. They work.
Posted 28 November 2010 - 02:27 PM
Posted 28 November 2010 - 02:34 PM
Posted 28 November 2010 - 02:55 PM
Posted 28 November 2010 - 03:58 PM
I discovered that breathing was a major problem for me during our "cold" (not nearly as cold as your area!!) nights - I needed to be exhaling in some other direction than onto the eyepiece; so I started to exhale downwards (towards my chin) through pursed lips, and avoiding any bundling against the cold that would redirect warm, moist breath onto the eyepiece. This seems to work for a while . . . but then there's the radiant heat from our eyes, lids, cheeks, etc. Haven't figured that one out yet but long eye relief eyepieces do tend not to fog-up quite so fast, at least for me.
Like Buddy I only use a couple of eyepieces during the coldest months, and I keep them in a vest pocket to keep warm . . . this; however is a little tough when using Axiom LX or equivalently large & heavy equipment.
Best of viewing,
Posted 28 November 2010 - 04:08 PM
I also like many people posted here prefer to keep the EP in my pockets. It's not only to keep them warmer, but also because I don't like to fumble in the dark, trying to find out which one's which. I keep my (only) 2" in the holder when not in use (it's the 30mm that came with the scope), whatever 1.25" is in the focuser, and one 1.25" EP in each pocket. That way I know exactly what I have where, and most of them stay warm.
Posted 28 November 2010 - 07:47 PM
Posted 28 November 2010 - 08:01 PM
I just got in from a quick looksee. Bringing a warm ep from the house straight to the scope worked perfectly.
I can't believe that didn't dawn on me!! I guess I figured I needed to cool down ep's just like my scope.
Posted 29 November 2010 - 12:55 PM
Is the fogging normal, or am I missing something to prevent it?
Rule #1: never expose the lenses at either end to the night sky. Those eyepiece racks that they sometimes include on Dobsonian rocker boxes look like a good idea, but they're not unless you put the caps on the eyepieces.
Posted 29 November 2010 - 01:04 PM
Posted 29 November 2010 - 01:19 PM
Lenses in clean pockets
Old, well-washed towel over lens when not in use--enough weight not to blow off
Hot water bottle (cheap/pink) or a chemical hand warmer in lens case
Dew buster and Firefly straps
...in some combination. Whatever works.
Posted 29 November 2010 - 01:55 PM
I learned to be aware of my breathing last year, when EPs fogging up constantly ended several viewing sessions.
I also encountered this in early Fall, when Dewpoints were still high. I have yet to find a good solution to it, except to keep caps on the ones not in use..
I do control my breathing at the scope these days, and leave the EP kit inside when the OT is outside cooling down..
Posted 17 November 2012 - 01:29 AM
Posted 17 November 2012 - 10:14 AM
Posted 17 November 2012 - 02:20 PM
Posted 19 November 2012 - 11:23 PM