The Heliopan Bay 3 #22 Orange Glass Filter for Black and White Film is used for producing contrast effects that darken sky and water, as in more dramatic architectural photography. This filter will also suppress blue. It makes clouds stand out even more than a #15 Yellow filter when shooting against a blue sky. Distant horizons will look even clearer.
Heliopan Lichtfilter-Technik of Munich, Germany has changed their black anodized brass filter rings on most Heliopan non-rotating filters to their "slim" mounts. These slim mounts are made of black anodized brass stock and have so little rim in front of the lens (5.4mm) that they will not vignette with lenses as short as 21mm.
Heliopan offers a wide selection of sizes, screw-in, series, bayonet, square and rectangular filters including digital, video, center weighted, graduated, wide angle, Kaesmann polarizers, drop-in polarizers, etc.