Having some problems here guys. I have a 67mm Marumi CPL, which I have used for quite a long time. I keep it clean with a blower and some microfiber.

However, until yesterday, I didn't notice some dust and small smears apparently on the surface. But when I tried to clean them, they were found to be between the two layers of the glass.

Is there any proper/alternate way to clean the CPL filters? Am I missing something?

  • 2
    \$\begingroup\$ If you have a low quality CPL, it will be nearly impossible to clean it correctly. I don't know if Marumi is high or low quality. If you have smears between the layers, I would say either it is a low quality filter, or it has been compromised by weather. \$\endgroup\$
    – dpollitt
    Commented Apr 3, 2012 at 0:05

2 Answers 2


If you cannot see the effect on the image quality, just leave it alone. Most imperfections on objective lenses are not visible in terms of image quality. However by repeatedly cleaning you run the risk of scratching the filter and making it more susceptible to flare.

See also http://www.lensrentals.com/blog/2008/10/front-element-scratches


I think you cannot do anything for the dust between the glasses. But you can clean your filters with liquid dishwasher detergent.


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