B+W 39mm Dark Red 091 SC
Compared to the lighter 090 red filter, this one even darkens the reds near the yellow tones in the spectrum, as its transparency only begins in the orange-red region. It produces dramatic effects and extreme tonal separation for graphic effects. That accounts for the large filter factor of appr. 8.
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%.