Filter fog?

[Ulophot]

(Not to be confused with fog filter.)

After some filter-factor tests made yesterday, I went to check more closely on my green (11), which appeared to be lowering contrast in an unexpected manner. It needed cleaning, as did several others, so out came the Eclipse and a PEC wipe. Two of the others cleaned up fine; the green and made polarizer not as well. The outer surfaces appear fine, but there is some sort of fogginess which must be between the glass layers. I haven't encountered this before.

I keep my filters together in a stack using metal end caps (Stackcaps or some such trade name).

Is this just likely an aging issue? I would guess these are 20 years old.

Thanks. It's always great to have this board for answers!

[LabRat]

Moisture, that dries up... Changes of air pressure slowly force moist air over time that cannot leave... It dries over internal surfaces, ultimately leave a haze...

Ammonia based lens cleaners will loosen the haze, but careful with too much rubbing and frequent applicator change, as the slight mineral residue can be a fine abrasive... Breathe on it a lot to keep it damp while cleaning...

Test first on one...

Steve K

[Bob Salomon]

All polarizers are a sandwich with foil between glass, except for Kaesmann polarizers which is edge sealed in glass the others can all be effected by heat, humidity, fungus getting between the glass.
Your green may well be a sandwiched filter also. Some of them sandwiched a gel while Tiffen uses colored glue to bond the glasses together. They are also susceptible to damage between the glass plates.
To eliminate that possibility in the future buy solid glass contrast and color filters in the future.

If the “haze” was on the surface and won’t clean off the cause could be plasticizers. This should not be a problem using good stack caps. But can be with plastic filter wallets.

[Drew Wiley]

PEC is not a lens cleaner, but a film cleaner. Old polarizers sometimes develop irrepairable issues.

[Ulophot]

Labrat and Bob, thank you for the info. bob. do the solid-glass manufacturers state that in their specs? I wouldn't know which brands to look for, except that -- I'm guessing here -- perhaps those are the $75 filters as opposed to the Tiffens or similar I have.

Drew, thanks to you as well. One minor correction: I only said a PEC pad. The PEC cleaner is indeed a film cleaner. Eclipse is a lens cleaner and, while I will try to avoid another endless debate (please take the hint, friends) and not say it's the best I have ever used, it works very well.

[Bob Salomon]

Labrat and Bob, thank you for the info. bob. do the solid-glass manufacturers state that in their specs? I wouldn't know which brands to look for, except that -- I'm guessing here -- perhaps those are the $75 filters as opposed to the Tiffens or similar I have.

Drew, thanks to you as well. One minor correction: I only said a PEC pad. The PEC cleaner is indeed a film cleaner. Eclipse is a lens cleaner and, while I will try to avoid another endless debate (please take the hint, friends) and not say it's the best I have ever used, it works very well.

Heliopan are dyed in the mass solid glass filter with slim brass rings. They cannot degrade like sandwiched filters and they are ground parallel for highest optical performance.

[roscoetuff-Skip Mersereau]

My favorite source for "new to you" filters is Tim Rice at: https://www.filterfind.net/Index.html
He's my go to guy, and prices are very reasonable. I'm currently waiting to hear back from him, but he's usually pretty quick. Highly recommended. YMMV.

[Ulophot]

Thank you, gents.

[C. D. Keth]

My favorite source for "new to you" filters is Tim Rice at: https://www.filterfind.net/Index.html
He's my go to guy, and prices are very reasonable. I'm currently waiting to hear back from him, but he's usually pretty quick. Highly recommended. YMMV.

Wow, I didn't even know a business like that existed!