The Tiffen 4x6" Deep Orange 21 filter darkens blue, violet, green and yellow-green.
Whether you're a color addict or devoted black and white shooter, this is an excellent filter to keep handy. With black and white film, contrast will be significantly boosted. Clouds will jump off the frame in stark contrast to a blue sky. Blue lilies become richer and more saturated. Most of all, the green end of the spectrum turns more pronounced.
With color, the addition of a deep orange filter to a simple sunset will enhance that image many times over making it more of a surreal scene.
Photographers of all disciplines should be aware of the many options that Tiffen color filters offer. Your photo - your imagination.