The Tiffen 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.
Tiffen 62SFX4 62mm Soft/FX 4 Filter