"clear" circular polarizers. is there such a thing as "clear" (not the tinted grey) circular polarizers?

For photographers using digital cameras, the polarizing filter is the most valuable to own and use. Light waves naturally vibrate in many directions unlike water waves that move only up – down. Objects appear to us as having color because they absorb some colors and reflect others. It is the reflected colors that we see and photograph.

Now the polarizing filter allows only those light rays that vibrate in one direction to pass. The polarizing filter thus blocks rays that are not aligned with the orientation of the filter. You can think of the polarizing filter as being ruled with super fine lines. Only light rays vibrating in parallel with these lines can transverse the filter. Because the polarizing filter passes some rays and stops some rays, it has density -- meaning it has a gray shade. Because it stops some light rays we must increase the exposure when we mount a polarizing filter. Doesn’t worry, your camera has the smarts to do this compensation for you.

We mount a polarizing filter because it removes unwanted reflections from glass and water and other shiny surfaces. Light from the sky arrives naturally polarized and we can use this filter to darken blue sky. This allows white clouds to stand out in boldly against the now darkened blue sky. The polarizing filter is the only filter that can enhance the boldness of colors without changing them too much. You must mount the filter and rotate it as you look via the viewfinder or view screen to get the best effect.

On bad thing: Many modern cameras use polarizing filters in their metering and focusing system inside the camera. This is bad because the polarizing filter can interfere and drive this automation crazy. The countermeasure is to mount a special polarizing fitter called a “circular polarizer”. Don’t worry, yours is probably one of these special types as they are now the ones being sold. The circular polarizer is actually two filters sandwiched together. The first is a polarizer the second is a “retarder”. The first filter does the polarizing, and the second unscrambles the light rays so they are harmless as to the cameras automation. The two sandwiched filters are a little bit denser but again the camera will automatically compensate for the density of the filter.

The polarizer as a filter was invented by Dr. Edwin Land cofounder of the Polaroid Corp. He imbedded crystals that naturally polarize light into plastic sheets. His company made polarizing sunglasses. Latter he invented a self-developing camera. This he called the “Polaroid”.

No. Polarizing filters are made to filter out some polarized light, so it's not possible to have a completely clear one. You can of course buy a UV filter that is totally clear, but it's not a polarizing filter.

Does not exist.