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A simple way to defog your lens...

PostPosted: Jan 16, 2007 10:24 am
by John Lovaas
I apologize if this has been already covered in other discussions or publications, but it seemed like a cheap and novel way to defog you camera's lens/LCD screen/viewfinder- or your survey instruments.

We were working in a very hot cave in Puerto Rico last week(hot, like 90F), and we had trouble with instrument fogging in the past. A friend pointed out to me that the root cause of lens fogging was that the lens was cooler than the surrounding air.

I had a brief flash of inspiration(or perhaps it was gas), and realized that a heat pack could bring the instrument(or lens, etc.) up to a an equal or slightly higher temp than the surrounding air.

I tried two different heat packs- "Toasty Toes", and a generic hand warmer. The Toasty Toes have an adhesive backing that allowed me to attach it to the lenscap, as well as the back of my Suunto Tandem. The Toasty Toes get up to about 100F, and the other hand warmers claim to get up to about 150F.

The Toasty Toe on instrument method worked perfectly. I still had fogging on my camera lens, though. To solve that, I activated one of the generic hand warmers and held the lens surface over it for several seconds- voila! No more fog.

As to keeping comfortable in a 90F cave- I recommend a Swaygo pack filled with ice, and a ziploc bag of ice in your helmet, replenished every 10-15 minutes from the stash in your Swaygo. Ahhhh....

PostPosted: Jan 16, 2007 3:42 pm
by Ralph E. Powers
Well that's all fine for the warmer caves but what about in reverse? Those cold caves and warm cameras? :grin:

PostPosted: Jan 16, 2007 8:03 pm
by chaz
Thanks for the tip! I've just started using a Kodak digital camera, and I'm having fogging troubles. I'll try a handwarmer this weekend in Fitton.

PostPosted: Jan 17, 2007 8:49 am
by Brian Masney
You can also use a candle (or a lighter) to remove the fog from your camera lens. I found that it works best to hold the lens a few inches away from the flame and to the side (not above the flame). Slightly blow on the flame and blow it towards the camera lens. The warm air should start to remove the fog. If the cave has a bunch of air flow, then you will have to find a way to block the wind.

Be careful that you don't melt anything on your camera!


PostPosted: Jan 18, 2007 12:46 am
by Bobatnathrop
Gah...I just about cried when I imagined putting a candle up to my camera. :shock:
All the caves around here are cold so the foot warmer thing wont work but that is a good idea that I will have to remember for later. If mine fogs this way I usually just cup my hand over the lens and wait it out.
Going from hot to cold though I dont have any ideas, I will just leave my camera case cracked while eating lunch or somthing and just wait it out.

put a little spit on it.

PostPosted: Jan 27, 2007 9:42 pm
by aplomb76
I learned this from SCUBA diving. You can use your own spit to prevent fogging in face masks. Today was the first time I took my DSLR into a cave and low and behold my lenst began to mist up. Rub a little spit on it. Voila. If you have an aversion to spitting on your very expensive lens, there are some commercially purchasable defogging applications that you can get at SCUBA stores.

PostPosted: Jan 28, 2007 12:32 am
by Dane
RainX makes a defogging agent for windshields, glasses, etc.

PostPosted: Jan 28, 2007 10:29 am
by John Lovaas
I have not tried the new RainX defogger- I will give that a try.

I've used Cat Crap for decades, and both my glasses and my camera and instrument lenses(treated with Cat Crap) fogged right up in the cave I mentioned previously. Cat Crap is good stuff, but it has limitations, I guess.

PostPosted: Jan 29, 2007 11:07 am
by hunter
I've been doing this for a while with a slight twist. I just start a foot warmer (can't remember the brand) and toss it into my Camera case which is insulated. As long as I don't take photos in the first 1/2 hour the camera is usually warmed up enough to not have fogging problems...

Well that's all fine for the warmer caves but what about in reverse? Those cold caves and warm cameras?

Unless I'm missing something the camera won't fog up in this case so what is the problem?


PostPosted: Feb 15, 2007 4:32 pm
by tagcaving
When bringing a cold camera into a warmer humid environment, fogging is always a problem. To help prevent fog from even forming, right after pulling your camera from the protective case, leave the lens cap on and press the end of the lens directly against your skin. (I use my chest) Your body heat will go through the lens cap and slowly heat the lens. It also helps to wrap your bare dry hands around the lens if you have a really big piece of glass. If you do this first and warm the lens enough, you can avoid getting fogged.

Once fog forms, if you do not have anything clean to wipe it off, put the lens cap on and press the flesh again. Once the lens element is warmer than the cave environment the fog should lift!

PostPosted: Feb 16, 2007 1:55 pm
by wendy
cool idea, i run into the fogged lens alot at work, i'll try it