Do circular polarizing red flters exist?

In my search for a red filter for 35mm b/w photography, I was told to

get a polarized red filter. The only ones I've found (google, BH

Photo) are linear red polarizers. This is an apparent problem on AF

cameras (see: Elan7). I would like to know if 1) red cpls exist and/or

2) if a linear polarizer would be okay to use in this event.

 

 

Thanks for any responses,

 

Michael

You could probably stack a red filter and a circular polarizer, but

of course, stacking filters shouldn't be done unless necessary,

because it results in more air/glass surfaces, and it may result

in vignetting on wideangle lenses. Still, it may be the simplest

solution.

<p>

The problem with linear polarizers on AF cameras has to do with the

beam splitter. The AF sensors and the metering cells are behind a

beam splitter, and this beam splitter is sensitive to the polarization

of light. Depending on the orientation of the polarizer, an

AF camera will probably meter incorrectly with a linear polarizer,

and will possibly focus incorrectly. If you're willing to turn

off AF and do your metering manually (meter before applying the

filter, then adjust your exposure for the filter factor), then

a linear polarizer should work fine on an AF camera.

Normal contrast control filters for B&W film (yellow, green, orange, red) have some significant advantages over any polarizer. If your intent is to darken skies, the contrast control filters will do it evenly across a wide view, and in any direction relative to the sun. Polarizers have their strongest effect at 90 degrees from the sun's direction, and the effect diminishes gradually when you scan away from that 90 degree arc across the sky. So polarizers darken the sky unevenly. Color photographers have no other alternative for darkening skies. B&W film users do have a much better choice, ordinary contrast control filters. Colored polarizers are used for creating distorted color special effects with color film. Whoever told you to use them with B&W film is misinformed.