Cleaning a Hoya polarizer: Mission impossible?

Discussion in 'Accessories' started by kanellopoulos, May 12, 2010.

  1. I am quite experienced in cleaning FF sensors.
    However, trying to clean a Hoya CPL filter proved to be too bad for my nerves...
    It seems that instead of removing dirt, I was just moving it around.
    I used a microfiber cloth and lens cleaning fluid by Kodak. Then I tried a pair of the wet/dry tissues that do a fabulous job on my monitor.
    After 15 minutes or so, I was still not satisfied at all with the result.
    Is there a reason some filters are so difficult to clean?
    For example, I find B+W filters much easier to clean. I also have no issues with my Singh-Ray polarizer.
    Any advice on the subject would be very welcome.
     
  2. I've never been able to get my B+W thin-mount polarizer perfectly clean.
     
  3. I really find it hard to believe that there is any appreciable difference (insofar as cleaning is concerned) between the surface of a Hoya and a B+W.
    What I can imagine is that you have got some specific thing that is fairly insoluble on the Hoya filter that you don't have on the others.
    There are solvents that will dissolve almost anything, but most would be a little too "efficient" for a recommendation to use them as a lens or filter cleaner.
    Have you tried a tiny, tiny bit of a grease-cutting detergent like Dawn™ and some water (just dampen, don't flood) on a nice, clean many-washings-old cotton cloth? Then wipe with just water.
     
  4. Here is a basic process I have used many times to clean some pretty bad looking lenses, such as those found on thrift-store cameras that have not been cleaned in years, maybe decades...
    1) Use a Hurricane blower to puff away all the visible loose dust. Puff vigourously but keep the nozzle tip maybe 2 IN from the lens or filter. Do this for about 1 minute, and move the blower all around to vary the 'angle of attack'.
    2) Next, use a clean softhair brush to carefully wipe over the whole surface of the lens or filter. This step is meant to remove or at least loose more stubborn dirt not blown away in step 1. A soft-hair makeup brush also works - just make sure its clean.
    3) Repeat step 1.
    4) Use one of thise isopropyl pre-moistened napkins you can get from WalMart. They used to be called Zeiss Lens Cleaning Napkins. But the last time I bought them they had switched to Baush & Lomb. You find them in the eye-glass accessory section. They come 50 to a box, and only cost a couple dollars.
    Open up one of these packets. Remove the isopropyl napkin. Unfold it all the way, then fold it in half 2 or 3 times to make it more manageable.
    Using a corner of the isopropyl napkin, carefully and smoothly wipe over the lens or filter surface using a smooth circular motion. Begin at the outside and work your way to the inside. At the end of each circular stroke, lift the napkin off the surface, like a plane taking off.
    If the lens has fungus, use a bit more pressure to clean off the fungus. But for ordinary dirt, use a more gentle pressure.
    In your case, you may want follow the isopropyl napkin with a more gentle cleaning using your preferred lens cleaner solution. I've just always gotten good results with the isopropyl napkin and never needed anything else.
    These same napkins are also good general purpose cleaners for just about any camera equipment, and I've even used them CDs & DVDs to clean them up.
    AP
     
  5. I believe that the polarizing filters are two sections with the outer glass rotating. therefore debris may have accumulated between the glass. You'll have to take the item apart to clean the inner surfaces of the front and rear glasses. I've never had to do this so cannot offer suggestions for disassembly!
     
  6. Cleaning inner surfaces of circular polarizer may require disassembly, as Paul described. This could result in destruction. The two rotating parts should be mounted very close together, and chances to make them dirty are smaller. I would not suspect inner surfaces get dirty. No finger prints on them. However, spills, mildew, etc. can get there.
     
  7. "Is there a reason some filters are so difficult to clean" .. Yes, some like B+W have a harder coating than others - or may not be coated at all, in which case the surface is also quite hard. At any rate, while there are two pieces of glass, they are in contact with the polarizing film and are not meant to move relative to each other or be opened. Doing so will probably destroy the filter. The best filters have the two glass surfaces fused together at the edges so moisture cannot penetrate and warp the polarizing film. Some filters like the variable-density ones from Singh-Ray, DO have surfaces that rotate relative to each other but I would not suggest taking these apart either.
     
  8. Be careful with liquids and polarizers. They are composed of a plastic film sandwiched between two pieces of glass. If liquid gets between the glass, the filter may be ruined. B+K Kaesemann filters are sealed at the edges.
    The "dirt" you are seeing is probably grease from the cloth or your fingers, which leaves shiny streaks. Cleaning fluid usually contains alcohol, which readily dissolves oil from your fingers and deposits it on the glass. Kodak fluid contains detergents which do not readily evaporate - I've never liked using it. Here are some suggestions...
    Handle the cleaning cloth carefully. Don't touch the part which will touch the lens, and don't soak the paper with fluid so that it reaches your fingers. It's best to bunch up the paper and use it like a crude brush.
    Before using cleaning fluid, try breathing on the glass and using a dry lens tissue (never paper towel or Kleenex - too abrasive, sometimes deliberately oily) or a microfiber cloth. That way there's no solvent to spread grease around. If you have a reuseable microfiber cloth, hand wash it in Wool-Lite from time to time, or dish washing liquid.
    The best cleaning fluid I've found is from Lenscrafters - a dilute alcohol solution for plastic eyeglasses. It's a good solvent for grease and spatters, but leaves absolutely no film on drying.
     
  9. Hi Edward,

    Humm dish washing liquid, do you mean hand dish washing liquid if so, not good for any thing you do not want to have smears of glycerine on. Most hand dish washing liquids have glycerine to protect the dish washers hands.

    Regards

    Rob
     
  10. david_henderson

    david_henderson www.photography001.com

    I also find Hoya filters much more difficult to get clean, and I find that their coating scratches much more easily than B+W. After a few months use ( which admittedly might involve time spent on the front of a lens sjust stuffed into my bag, or lying loose in the bag) my Hoya Pro 1 polarisers are covered with marks , the B+W equivalents are almost unmarked. I don't suppose these marks- which almost look like the coating has peeled off in places- have a big effect on image quality and indeed they are only strongly visible at certain orientations to the light - but it does convince me that "coatings" on Hoya and B+W polarisers are quite different things.
     
  11. david_henderson

    david_henderson www.photography001.com

    I also meant to say that I find dish washing liquids the easiest way to get grads clean. I only need t do this a time or two a year but squeeze a few drops onto the filter, rub it gently over the surface, rinse with clean water (distilled water if you're in a hard water area), pat gently dry on absorbent kitchen towel and then when dry polish with a microfibre cloth. Seems to work OK , and no signs of marks from glycerine.
     
  12. Coated filters are difficult to clean as compared to non-coated optics. Often the coat has a "tooth" that captures and holds oils.
    As to coatings, seems Harold Taylor in 1892, an optician, noted that old lenses passed more light than new ones of the same design. Seems atmospheric pollution deposits a thin film of contamination on glass that somehow decreased light loss. As light transverses a lens, some light energy, about 5%, is reflected away by the shinny polished glass. A natural thin film deposit somehow cut this loss to 2%.
    Investigators discovered that it was the thickness of the coat that did the trick. By 1935 it was common practice to artificially age lenses "blooming" by applying a thin coat of fluoride or silicon dioxide or aluminum dioxide. To work the coat thickness must be 1/4 of the wave length of the color of light you are controlling. A multi-coat is many layers, each a different thickness. Modern lenses are now double of triple coated. Super duper lenses can have 7 - 11 coats.
    A coated lens passes more light plus the coating minimizes flare and ghost images. As you know, the modern camera lens is a multiple element array. Each glass element has two shinny polished surfaces that reflect light rays. Some percentage of the reflected light goes astray. These misguided rays induce flare and ghost images. Coating and an effective lens shade mitigates.
    The mounted filter adds extra surfaces and exuberates the problem. Thus, modern filters are also coated. Now a coated glass surface is far more difficult to clean than uncoated glass. Buy ethyl alcohol at the liquor store, ever clear is a brand with 99% ethyl alcohol. I clean especially dirty lenses with this stuff. I mix this with distilled water 25% alcohol. For oils like fingerprints, add a drop or two of liquid disk soap. You can also use vodka, its 50% ethyl alcohol and purified water
     
  13. Humm dish washing liquid, do you mean hand dish washing liquid if so, not good for any thing you do not want to have smears of glycerine on. Most hand dish washing liquids have glycerine to protect the dish washers hands.
    I said "cleaning fluid" for the filters. Dish washing liquid (the hand type) will do a good job on microfiber cleaning cloth. Glycerine is water soluble. If you rinse the cloth thoroughly after washing, you should have no problem. Dishwasher (machine type) detergent is usually highly caustic, and should not be used.
    If coated lenses/filters seem hard to clean, it is only because the surface has such a low reflectivity that a thin film of oil is shiny by comparison. That said, some coatings are much softer than others, and can be damaged by careless (or frequent) cleaning. This damage will appear as shiny swirls, or in severe cases, as scratches. MRC coatings, for example, are harder than the underlying glass, and highly resistant to abrasion.
     

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