People People People! You are forgetting to answer the question the person asked. Now I'm confused! (as always) So Werner the bottom line should be. Remember to remove your Polarizer when you are using a flash.Whenever I forget to do this, my pictures come back looking a little grainy, with low contrast. I think that the polarizer cuts down the exposure by one stop (or maybe even more when it is fully activated) and somehow screws up the camera's ability to get the correct exposure. That's just a guess, but whatever it does, the results are not pleasing to the eye. If you still want to protect your lens when you're not using your polarizer, get a skylight filter. And as Michelle has said... Polarizers come in two varieties, 'linear' and 'circular.' Each has the same effect visually; the difference is just in the way they polarize the light passing through. If you own an auto-focusing camera , use a circular polarizer, which won't interfere with its automatic functions. My result with using a liner on a digital camara with auto focus on which it's most of the time, I get alot and I mean alot of grainy pixels on anything thats blur in the back ground or in fields of thirds. Maybe I see these more than other because I'm using bright lights in studio production with strobes. But I do also agree with Jordy I have not notice it in regular day to day home shots. now we will be right back after these "fetishes"