Polarizing filter causing soft, hazy shots?

Question

I'm having a problem with a polarizing filter that's I've used for years.

I have a Nikon D7000 w/18-200mm lens. I keep a UV filter on the lens, and on occasion I add a circular polarizer, which just recently began giving me images with exactly the opposite result that I'd expect.

Today for instance, I shot some beach scenes and later a waterfall against the blue sky. As a test due to some failed shots earlier in the week I tested a theory. I shot a few on a tripod with the polarizer. I turned it until the sky was deep blue and the glare was off the water. Looked great in the viewfinder.

I get home and the images look like I had the polarizer set 180 degrees out. They're hazy, soft and almost out of focus.

Now the test I mentioned was that I changed nothing but taking the filter off the lens and the shots look great. Clear, vibrant and crisp.

Compare both images:

So I ask, is it something I'm doing, Never had this issue until recently. Do polarizing filters go bad?

Answer 1

Every bit of glass you place in front of the lens will cause flare. In general, expensive filters cause less flare than cheap ones, and fewer filters cause less flare than more filters.

When you think lens flare, you may think of the circles or shapes that appear in frame as reflections of the sun, but lens flare refers to all unwanted light coming from reflections inside the lens assembly, and can manifest as an overall "haze" or reduction in contrast (exactly like in your example image).

• Make sure your filters are all multi-coated. I'm referring to the anti-reflective coatings. Uncoated filters will cause lots of flare (whole orders of magnitude more flare) while single-coated will still cause noticeably more than multi-coated ones.

  Note: all the elements in your lens itself will be multi-coated on any surface exposed to air. You lose the benefit of multi-coating if you add just one filter/piece of glass in front of it all that isn't multi-coated.

• Make sure the filters are clean. Any dirt or oily smears on them will increase flare or haze.

• For goodness sake, remove the UV filter when putting on the polariser. No need to have more flare than you absolutely need. I'd advise not using a UV filter at all, they are good for nothing other than increasing flare. That, however, seems to be a controversial statement to some photographers, so if you are religiously opposed to shooting without a UV filter then by all means make sure it's a good one and that you take it off when you add a different filter.