Removing lens condensation?

I went to trade a lens in at B&H and they said they saw some condensation and wouldn't take it in trade. The lens works fine and I don't notice any problems when using it. I recall reading about methods to remove lens condensation but can't seem to find it. (Don't know if it was on this forum or elsewhere). How is this done? Thanks.

Get a gallon bag and put white rice in it, then put the lens in it to help dry it out. Only works if your lens is on the smaller side, else you will have to employ larger bags or a container.

Although you will read that this isn't the best way. I would suggest going to your local walmart and getting a bag of the silica cat litter (usually $8-10 a bag and called cat crystals) and use that instead, that is its purpose. It is nothing more than bulk dessicant.

cristphoto wrote in post #19345754
I went to trade a lens in at B&H and they said they saw some condensation and wouldn't take it in trade. The lens works fine and I don't notice any problems when using it. I recall reading about methods to remove lens condensation but can't seem to find it. (Don't know if it was on this forum or elsewhere). How is this done? Thanks.

What lens is it?

70-200 LIS 2.8

After posting this I was digging around you-tube and one guy said to eliminate getting any small particles inside the lens insert the lens in a sock and use a rubber band to seal off the end. It still breathes but nothing (hopefully) enters the lens. Sound OK? Also how long does dessicant last? I have several packs from lenses and bodies I've purchased over the years. Perhaps take all of them and stick in a zip lock bag with the lens?

cristphoto wrote in post #19345769
After posting this I was digging around you-tube and one guy said to eliminate getting any small particles inside the lens insert the lens in a sock and use a rubber band to seal off the end. It still breathes but nothing (hopefully) enters the lens. Sound OK? Also how long does dessicant last? I have several packs from lenses and bodies I've purchased over the years. Perhaps take all of them and stick in a zip lock bag with the lens?

I'm no lens technician, but I'd avoid using cat litter as suggested above. Maybe "silica" litter is different, but cat litter tends to be very dusty with extremely fine particles breaking off the larger particles. No sock is going to be able to filter that. I'd also avoid putting the lens in contact with anything they may have other unknown chemicals in its composition.

If it were me, I'd buy a 20lb bag of rice, put the lens in a pillow case, submerge the pillow case into the rice, and seal everything inside a large garbage bag. Leave it for at least a week (2weeks is probably better) and go from there. The concern I'd have would be that fungus/mold/mildew developed since the moisture has been there for some time. I'm not suggesting you would do this, but please don't make the mistake of selling the lens without disclosing the condensation, especially so if you are thinking about selling on the forum as someone will surely come across this thread.

I would avoid anything that can make a powder, rice, cat litter, silica gel, all are very dusty and likely to cause other issues. It's easier to raise the temperature of the lens for a few hours and let the water evaporate. Put the lens in the sun, place it in a box with a heat lamp, use a hair dryer to warm the lens work well. Just be careful to not get it too hot.

However, I suspect that B&H is seeing the reside left behind like water marks or spots on the elements. Canon will not warranty lenses that have had any water damage as it can play havoc with the internals.

BTW, if you have a dehumidifier, it works better than any other method especially if you reduce the volume like placing the dehumidifier in a large box and covering it. It will dry the air inside and given a few hours, will also dry the air inside the lens as well.

I used to work on the Alaska pipeline and one thing we did, at the end of the day, when many of your lenses had condensation, was to wrap them in a heating pad set on low or put several in a box that had a heating pad on the bottom. When you initially use a heating pad, stick you hand in every 15 minutes to make sure the low setting isn't too hot. My Sunbeam pad is labeled as 110 deg F on low, 138 deg on medium and 160 deg on high. I would not want the 138 or 160 deg settings, 110 is likely about what you lens would be in use on a sunny summer day. Also be aware that most heating pads have an auto-off at 2 hours so when it shuts off, then re-examine the lens.

Strange situation where B&H notices condensation when the owner hasn't. If there really is water in the lens, there could be more problems with this lens, and other gear belonging to the owner too. There has to be more to this story.

Archibald wrote in post #19350402
Strange situation where B&H notices condensation when the owner hasn't. If there really is water in the lens, there could be more problems with this lens, and other gear belonging to the owner too. There has to be more to this story.

Good point...one has to wonder if the lens was removed from the package in B&H warehouse and then examined. I could envision where the lens may have been quite cold (Brooklyn had some 20 deg F temps in mid-February) and then examined in a heated room.

John from PA wrote in post #19350438
Good point...one has to wonder if the lens was removed from the package in B&H warehouse and then examined. I could envision where the lens may have been quite cold (Brooklyn had some 20 deg F temps in mid-February) and then examined in a heated room.

I'm pretty sure B&H would recognize a case of condensation in a warm space on a cold lens. That would result in a lens that is moist on the outside rather than having condensation inside.

When water is discovered in a lens by chance, most likely it was there for a while and the lens has already suffered corrosion and/or fungus damage.

The heating pad is an awesome idea. Might add some slow air movement (a fan) to that.

As I stated in my original post the lens works fine and I see nothing on the files even when viewing at 200%. B&H said they had a memo from Canon that this version of the 70-200 had issues with condensation so I wonder if they simply didn't want to take this lens in on trade with or without condensation. Nothing is visible looking at either end of the lens with my bare eye, so I wonder if they partially disassemble the lens and look inside. Its about 15 years old so if all of a sudden it dies I would have got my fair share of use from it.

cristphoto wrote in post #19351633
B&H said they had a memo from Canon that this version of the 70-200 had issues with condensation...

Very strange. More info needed.

Normallly if there is condensed water in the lens, you would be able to see it easily with your bare eye. But in case it is subtle, try shooting a small bright light in a dark room or outside at night and look for flare or halos around the light.