This Heliopan Bay 3 KB 6 Cooling Color Conversion Glass Filter is useful for balancing light sources with a color temperature of 3800K for daylight film, which is designed to accurately reproduce colors under 5500K light sources.
Note:
This filter is specific to lenses with Rollei's exclusive B3 (Bay 3) filter size
Heliopan cuts, grinds, polishes and coats their filters with the same techniques and equipment as used for the finest German camera lenses
All Heliopan screw-in type and series size filters are mounted in precision black anodized brass rings to eliminate binding or cross threading and to ensure optimal alignment
Filters still retain front threads for a lens cap, a lens hood or even stacking a second filter
The portion of the Heliopan slim filters that are in front of the lens have been reduced in thickness by 37% over the former mount
80 Series Color Conversion Chart
80A increases color temperature from 3200-5500 Kelvin (commonly used with 3200K lamps)
80B increases color temperature from 3400-5500 Kelvin (commonly used with photoflood lamps)
80C increases color temperature from 3800-5500 Kelvin (commonly used with flashbulbs)
80D increases color temperature from 4100-5500 Kelvin (commonly used to remove extreme orange or red)