I lost my Yellow contrast lens on a recent outing. The BAY 1 or B30 filter must've fallen out on the way home somehow. Anyway in the Rollei bag among sundry other items is a F&H Pol1 lens. IT is turnable. I guess if I google this I will find some info. I always assumed a polarizing filter was used for color as a contrast or antiflare etc. In B&W work it would act as a ND filter. Would the polarizing filter act as a contrast filter ie enhance the clouds to a degree?? A yellow filter reduces circa 2/3 or a full stop.