One of my circular (rotating) polarizing filters has a big hair between the two lenses. The hair moves around and I always have to shake it aside until it's out of sight.

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How would I go about disassembling it and reassembling it (after I get rid of the tiny annoying hair)? I haven't been able to find any help/tutorial online and I'm not sure how the parts are welded together.


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I don't know that this necessarily applies to your CPL, because it probably varies quite a bit by brand, model, etc.

However, on at least one brand CPL and GND filter I have, inside the front ring, using the same threads you'd use to stack a second filter, there is a very slim retaining ring that unscrews out the front, letting the glass fall out once it's out. There may be a similar arrangement on the rear. Having never fully disassembled one, though, I'm not sure how to separate the front half from the back half. But, if you can get one glass surface out, you should be able to clean the hair out. Just be sure you pay attention to which surface of the glass pointed which direction.

It's quite possible, though, especially on cheaper models, that everything may just be cemented in, in which case things get quite a bit more difficult.

One other thing - you might take some shots of a clear sky at something like f/22 with the CPL on and see if you can even detect the hair in the resulting photo. Chances are extremely high that you can't. So, it's almost certain that you don't really need to do this - that hair bothers you a whole lot more than it's likely to bother the capabilities of your filter/lens/camera.

  • \$\begingroup\$ Also keep in mind that the quarter wave plate (the rear layer) must be at a 45° angle to the direction of the front polarizer for it to work properly. It would probably be wise to make some (eraseible) reference marks on each side before disassembling. \$\endgroup\$
    – Michael C
    Commented Aug 2, 2019 at 3:59
  • \$\begingroup\$ @MichaelC don't mind me if I misunderstood, but it's a rotating CPL so would you need to? \$\endgroup\$
    – timvrhn
    Commented Aug 2, 2019 at 7:43
  • \$\begingroup\$ @timvrhn Yes. The second plate, which is a quarter-wave retarder, needs to be at a 45° to the actual linear polarizer to get the benefit of a circular polarizer (instead of a plain old linear polarizer). Both have to be rotated in unison so that the 45° angle is preserved. \$\endgroup\$
    – Michael C
    Commented Aug 3, 2019 at 2:36
  • \$\begingroup\$ Yes, but seeing as how it's a rotating CPL, why bother making marks before disassembling? You just turn it as it's reassembled \$\endgroup\$
    – timvrhn
    Commented Aug 3, 2019 at 8:03
  • 1
    \$\begingroup\$ Ah that makes perfect sense @MichaelC, I was confused at the functionality of that turning ring. Cheers! \$\endgroup\$
    – timvrhn
    Commented Aug 5, 2019 at 4:47

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