Mystery of the Fotar Variocolor...

I received a Fotar Variocolor R-Y filter as an unexpected bonus with a camera lens that I received. The filter somehow olarizes the light and applies a variable color filter (from Red to Yellow) as the knob is rotated.
A red filter (in B&W film cameras) is used to darken the sky. Unfortunately, it was so cloudy that I did not see much effect.

The yellow filter made the world, well... yellow. The look of aged film.

Converting the red image to B&W gave a very film like style to the photo. The Vario color appears to have a polarizer in it, so the effect may not be able to be simulated in photoshop.

I'll take the lens out next weekend and give it a test.