Soft Effect is a diffusion filter designed to affect resolution in a pleasing manner by reducing high frequency details like wrinkles and blemishes in skin while leaving other areas of the image unaffected.
Soft Effect is made of fine white color particulate that is bonded between two pieces of Schott B270 Optical Glass which exceeds 4K resolution capability. The particulate ranges in size from slightly smaller than a pixel to slightly larger than a pixel size to alter incoming light that creates the pleasing reduction in resolution with a slight effect on contrast.
Available in strengths of 1/16, 1/8, 1/4, 1/2, 1, 2, and 3. Most users seek a slight almost unnoticeable reduction in resolution therefore the 1/8 strength is the most popular.