Removing Fog in Lens

[Klose]

I am currently thinking of sending my lens to TCH to remove the fog in the lens. Does anyone know what exactly happens when the remove fog from lens?

[Jemapela]

Could you describe the fogging? What brand of lens is that?

I have 2 lenses which fogged long ago, a Yashica 75-200mm and a Sigma 400mm APO.

Yashica said the fogging was due to heat. The fogging cannot be removed, and replacing the affected element is not worth it.

With that explanation, my Sigma 400mm APO is now a paperweight.

[pcwe68]

ya, seems like that's the case, fogging cannot be cleaned totally.
but usually if it is not too serious, the picture quality will not be affected.

Anyway, no harm bringing down to TCW, they will be able to advise, hopefully its not fog but just some fungus.

[Klose]

hmm what i can see is that there's layer of dust particles in the inside image quality isnt affected at all

[Klose]

Originally Posted by Jemapela Could you describe the fogging? What brand of lens is that? I have 2 lenses which fogged long ago, a Yashica 75-200mm and a Sigma 400mm APO. Yashica said the fogging was due to heat. The fogging cannot be removed, and replacing the affected element is not worth it. With that explanation, my Sigma 400mm APO is now a paperweight.

it's a tamron 70-300mm good lens it's more of a dust layer

[billpepsi]

Originally Posted by Jemapela I have 2 lenses which fogged long ago, a Yashica 75-200mm and a Sigma 400mm APO.

Were the lenses kept in dry cabi all the time? I know fungus can kill the lens, but didn't know heat can cause fogged

[pcwe68]

seems like fogging is caused by heat. Can anyone explain that?

[Jemapela]

Originally Posted by jeffhiew Were the lenses kept in dry cabi all the time? I know fungus can kill the lens, but didn't know heat can cause fogged

Yes, they were all kept in a dry-cabinet, frequently monitored and maintained around 30%-50% RH.

In fact, I left them almost untouched for over a year, and when I took them out 1 day, I saw them fogged. Worse, the 400mm APO was NEVER used (because I was in Australia all along) but it passed it's warranty.

I was told by a friend who read an article that said some Canon L series lenses will also fog after say 10+ years of use. I can't verify that.

[Jemapela]

Originally Posted by Klose hmm what i can see is that there's layer of dust particles in the inside image quality isnt affected at all

Goodness, a layer of dust? You took your lens into the Iraqi dessert ah?

If it's fogging/fogged, you can't see through the elements in the barrel. It looks like a thin tissue paper put into the barrel. My lenses were that fogged! They couldn't even be used as a soft-focus lens.

[Klose]

Originally Posted by Jemapela Goodness, a layer of dust? You took your lens into the Iraqi dessert ah? If it's fogging/fogged, you can't see through the elements in the barrel. It looks like a thin tissue paper put into the barrel. My lenses were that fogged! They couldn't even be used as a soft-focus lens.

no la

actually from what i read some where once lenses dont get used for a while, they will get fogged even when left in the dry cabi or box due to the dust particles settling on the element

[pcwe68]

fogging is fogging and dust is dust right? are they related and the same thing?

[Jemapela]

Originally Posted by pcwe68 fogging is fogging and dust is dust right? are they related and the same thing?

Fogging is fogging. Dust is dust. They are NOT the same.

You can't remove fogging because it's a damaged coating on the glass element. (Perhaps, you can scrape away the coating?)

You can remove dust by blowing away. (I can't understand how so much dust can settle on the elements if you kept the lens sealed up in plastic bag and box.)

That's why those 2 fogged lenses of mine are now really useless paperweights!

[whoelse]

I have a Sigma APO oso fogged. I check googles and seems like a common problem -- coating degraded. The Zen finish oso degrade when age. That is why I do not buy Sigma lens nowaday even they are optically not bad.

[hongsien]

Fogging (not due to fungus) is caused mainly by the oil inside the lens and from the aperture blades evaporating, especially during increased temperatures.

Another factor could be that some lens elements are from plastic which may turn foggy over time.........could be that it 'degrades' over time, or oxidises.......but I am no chemist and I am not sure what material these elements are made from? It could be that some of the chemicals that make up the element turns into the gas state, and the remaining 'plastic' changes to a foggy plastic.........I heard many Sigma lenses suffer from this........

HS

[F5user]

yup... what hs said is true to what i've known.

And, almost ALL the sigma lenses i've owned for the past 10 years, including the later versions which were produced from 2003 onwards, have almost always fogged up after 2 -3 yrs of use.

Though sigma's warrenties its equipment for that, i still choose to use the lens and sell it after 2 yrs.

I read that it's due to the material within the lens (carbonate/plastic composites), and also, with their coating.

[Klose]

got someone to check for me, was told it was the after effects of slight water moisture getting into the lens but the damage is superficial as image quality isnt affect :P

[Jemapela]

Originally Posted by F5user And, almost ALL the sigma lenses i've owned for the past 10 years, including the later versions which were produced from 2003 onwards, have almost always fogged up after 2 -3 yrs of use. Though sigma's warrenties its equipment for that, i still choose to use the lens and sell it after 2 yrs.

Most lenses are warrantied for 1 year. Does Sigma automatically extend that warranty longer for fogged lenses? I doubt they have such generosity.

I wished someone had told me this long ago before I bought that Sigma 400mm APO.

Anyway, do you know if the Sigma 15-30mm lens has this problem?

[dRebelXT]

A lesson I learnt is, I won't buy a lense and leave it idle for 3 or 10 years.

[F5user]

Originally Posted by Jemapela Most lenses are warrantied for 1 year. Does Sigma automatically extend that warranty longer for fogged lenses? I doubt they have such generosity. I wished someone had told me this long ago before I bought that Sigma 400mm APO. Anyway, do you know if the Sigma 15-30mm lens has this problem?

well... according to sigma, and loyal sigma dieharders, they don't.. but the forums i've run through here in the usa, i still meet ppl complaining of fogging especially if they live in coastal cities... (ie: Long beach, LA)

I don't know about that lens per say, but honestly, i wouldn't risk it... save a bit more, and buy a nikon/canon lens.

I myself am praying that the 12-24 i'm using doesn't fog up soon.

[F5user]

Originally Posted by dRebelXT A lesson I learnt is, I won't buy a lense and leave it idle for 3 or 10 years.

If u leave ANYTHING idle for 3 - 10 years, (gf, wife, camera, food, lens, etc)... i would say that you're