Both the Schneider Series 9 81-One and the 81-Two Warming Color Conversion Water White Glass filters are designed to add warmth to skin tones and reduce excessive blue in outdoor open shade.
It's Autumn. The clouds are low hanging and the sky is "patchy blue". You've gone for a ride upstate to the mountains and the light in open shade is bluish. A photo taken of your girlfriend with daylight balanced film leaning against the side of a barn will yield bluish tones that she might not find particularly flattering.
An 81 filter will replace some of the yellow missing from the image and bring her skin tones back to a more appealing level. The 81 series allows you to choose how much warmth you wish to replace in the image.
The 81-One is more appropriate for a subject with darker skin tones
Ideal for romantic close-ups
The Schneider 81 Series can be combined with softening filters
Schneider solid color filters feature crystal clear, water-white optical glass, protected against edge-chipping and delamination by Schneider's unique Edge Seal, which also significantly reduces edge reflections and flare
Schneider Quality Control
Schneider filters are ground and polished to a precise flatness and plane parallelism
Because all Schneider filters are designed and manufactured with the highest possible degree of consistency, you can swap like filters mid-shoot with no discernible variation in color or effect
Schneider 81-1 Specs
Not Specified by Manufacturer
The 81 series adds warmth to the image
Good for general scenery when the photographer wishes to remove the bluish cast from open shade or just add warmth to the photograph