Nikon CLP-filter: one of four has fogged

<p>I have four Nikon CPL filters of different sizes. All are about the same age and have been stored and used about the same way.<br>

Now it seems that one (58mm) has got or has had from the beginning some haze on it. The haze can be seen and can be compared to the other filters by an eye. Darker subject matter seems to be less contrasty via the 58 mm filter than via others. Turning the filters does not change the status or behaviour. <br>

Cleaning does not help. I have used even Zeiss lens cleaning wet cloths without any help. It seems that the problem with this unit is evenly dirtributed and maybe somehow internal - not on the surfaces.<br>

Any comments?</p>

<p>As you know, polarizer filters (circular or linear) have two pieces of optical glass stacked together. Did you take the filter apart, separate the two pieces and clean the internal surfaces facing each other?</p>

<p>I have several Nikon and non-Nikon polarizer filters. Some are very old, e.g. the old-style oversized Nikon polarizers, and I have never seen any optical filter turning foggy inside the glass.</p>

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<p>Did you take the filter apart, separate the two pieces and clean the internal surfaces facing each other?</p>

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<p>Is that really a good idea? I thought that CPL filters have the polarizing medium laminated between the two glass surfaces and that taking them apart and cleaning the interior surfaces seems like a sure way to destroy the filter.</p>

<p>I don't know whether it is a good idea to take a polarizer apart to clean it; that is up to the owner to decide.</p>

<p>However, I think one possibility is that some moisture (or dirt) has gotten inside the OP's polarizer between the two glass elements. If that is indeed the problem, cleaning the outer surfaces of the polarizer is not going to fix anything. So I am trying to figure out exactly what kind of cleaning Kari has done.</p>

<p>It might not be all the easy to put a polarizer together either. It is up to the owner to decide how to fix it. But worse comes to worse, if you need to replace a 58mm polarizer, you are out maybe $85 or so. It is not going to be the end of the world.</p>

<p>Dieter is correct. A polarising filter consists of three elements; two clear protective glass flats with a thin polarising pellicle cemented inside them. I've seen, and owned, quite a few polarisers where the thin polarising film has wrinkled and/or separated from the glass flats. Once that's happened there's often some misting between the parts, and I'm pretty sure that the filter is then a complete write-off. Or at least hardly worth the trouble of dismantling and trying to clean and reassemble. Especially if it's a small sized one like 58mm.</p>

<p>Edit: I believe the delamination is often due to heat or high humidity. The dark filter absorbs a lot of heat if left in direct sunlight for any length of time.</p>

<p>Thank you so far. Just wondering why there is one that is visibly more foggy. This applies to the whole surface evenly. One can see the problem best by looking a dark scene through the filter when light hits the outside of the filter. Those other three units do show some of the "fogging" while this 58 mm unit shows it at least a double amount.<br>

I had one CPL made by another manufacturer. It was forgotten into its case for a week or so with some moisture that had got in. The result: edges of the bonded layers were separated and the filter was lost. This could be seen from the other side by the reflection at the edges.</p>

<p>However at this time the situation is different as the fogginess is totally even. So two possibilites come to my mind. Either a manufacturing issue or my camera bag has emitted something that has affected the filter. But then there is the question of why eminently only one filter.<br>

Cleaning: outsides only. First with alcohol solvent (should be ok altough not intended for this purpose). After that was not enough I did the cleaning with Carl Zeiss wet lens cleaning cloths. Those are very good for lenses at least.<br>

Now outer surfaces of all four CPL-units show a similar, clear green reflection when properly viewed. Only one unit shows something, when seen through, that will result to image contrast lowering.</p>

<p>How well, in general, CPL-filters tolerate backlight situations?</p>

 

<p>Kari - I'm not sure exactly why one would use a polaizer in a backlit situation, the plane of polarization would generally tend to be prominent in side lighting rather than backlit, unless the background itself constitutes the plane of polarization and there is a different plane of light on the subject (such as a person against the sky where the sky constitutes the plane of polarization, and the person is lit with fill light from the front).</p>

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<p>Kari - I'm not sure exactly why one would use a polaizer in a backlit situation,</p>

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<p>Yes, true. This time I was misusing the polarizer as a 1.5 stop ND filter as the 64ND -6stops- was all too much. Flash outdoors, and my camera does not naturally go to 64 ISO ;-)<br>

A third possible explanation to fogging might be the liquid I have been using to clean my lenses and filters. Lenses have been tolerant but those CPLs less.</p>

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<p>A third possible explanation to fogging might be the liquid I have been using to clean my lenses and filters. Lenses have been tolerant but those CPLs less.</p>

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<p>I think that's quite likely. Apparently even high quality polarisers aren't usually sealed at the edge, so if cleaning fluid migrates to the rim it can get into the inner polymer layer. I guess high humidity could affect the material via the same route. B+W's expensive 'Käsemann' polarisers do have edge sealing, and so should avoid this problem.</p>

<p>The Kaesemann filters by Schneider optics not only have the edges sealed but they also use a different glass and foil for the filtering.</p>

 

<p>Initially asking the CPL question, I was aiming to solve two objectives: firstly to avoid other filter units to eventually appear as foggy as the 58mm unit is now. Secondly I wanted to save, not use more, money.</p>

<p>Unless it is a manufacturing issue, then it is highly unprobable that water or lens cleaning fluid would have gone inside the polarizer element. These elements are somewhat tolerant as similar components in sunglasses prove. The active filter area is uniform, no more or no less fogging at the edges.</p>

<p>It seems that I have to at least replace the 58mm CPL, maybe 52 and 77 too. Also I have to stop using my current - for 10 years or more - alcohol solution. It has worked for lenses but probably not for those filters. Maybe the coating or the glass material is different.</p>

<p>Now all four CPL filters are thorouhly cleaned, the coatings seem to be fine. Shining a flashlight through results a cloudy spot where the light beam hits the filter - best seen with the 58mm filter.</p>

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<p>"Also I have to stop using my current - for 10 years or more - alcohol solution."<br>

First rule in using a cleaning fluid on anything photo related is to lightly moisten the wipe and apply to lens or filter. NEVER apply solution directly onto the surface to be cleaned. It will migrate. In your case, if this was the cause of your problem, consider yourself lucky. The filter is relatively inexpensive. I have seen cases where a photog squirted cleaning solution directly on to a lens only to discover that it seeped into the inner workings of the zoom. <strong>That</strong> was an expensive lesson.<br /> For that matter, suggest using fluid as a last resort when other cleaning methods fail. I can clean up 85% of anything on my filters or lens elements with breath on the surface and a micro fiber cloth or a Lens Pen only. I find that I seldom need anything more than that. I bought a 2 or 3 oz bottle of Eclipse 5 or more years ago and it is probably 75% full right now.</p>

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