It happens because the polarizer works better on some parts of the sky than others. And, since you’re capturing such a wide part of the sky with a wide-angle lens, you’re almost always going to run into this problem.
Sure, you could avoid this problem all together by not using a polarizer on a wide-angle lens, but then you wouldn’t be able to take advantage of the other great benefits of the polarizer: reducing unwanted reflections, and saturating colors. [Read more…] about How to Fix a Washed Out Sky In Photoshop