The Tiffen 2 x 2" Warm Soft/FX 4 Filter diffuses strong light entering the lens and produces a glowing effect. While the resulting image appears softer and ethereal, there is little loss of clarity or detail. This filter works by diffusing the light entering the lens with small aberrations; by spreading the light more evenly, a soft glow is created rather than the sharp, well-defined image when shooting without a filter. The 4 density provides more softening than the 3, but less than the 5.
This filter also combines the diffusion effect with an 812 warming filter for providing a general warmth to the image and for improving skin tones. This warming effect also helps to reduce blue sensitivity and for cutting through overly cool tones within the scene.
Tiffen filters are made using ColorCore technology, a process that involves laminating the filter substrate between 2 pieces of optical glass and grinding flat to a tolerance of 1/10,000th of an inch. This filter measures 2 x 2" / 50.8 x 50.8mm.