The B+W 60HSB KR-1.5 SC (Skylight) Filter is a reddish-yellow conversion filter absorbs violet and some blue plus a minimal amount of green, but it passes yellow and red undiminished; the color of the light becomes “warmer” by 15 Mired. That is mostly the optimal amount for correcting the light blue cast in the shadows under a blue sky. It also absorbs UV radiation and hence it provides better sharpness. With color films and/or developing processes that generally yield results that are too “cool," this filter can be kept on the lens at all times. With this filter, skin tones in particular will be rendered more naturally. Its filter factor is approximately 1:1.
This filter uses a HSB mount made of brass. Various lenses for Hasselblad cameras are equipped with bayonets for the attachment of filters and lens hoods. The advantage of a bayonet mount over threaded filters is quick attachment and removal. HSB 60 and HSB 70 are offered.
Each glass surface is vacuum coated with one layer of Anti-Reflection coating. This single layer helps to prevent internal ghosting and reflections. It also improves light transmission from approximately 92% (uncoated glass) to over 98%.