Diffusion filters soften the image. They reduce fine details as skin imperfections without affecting the sharpness of the image. Modern lenses are often so sharp, that skin does not look nice, showing every pore and winkle. Diffusion filters smooth those blemishes and create a flatten skin, providing a romantic, pleasant look, without defocusing the scene.
Diffusion filter also add highlight flare, putting a halo around blown windows, light sources, or areas of high exposure. Can also be used to reduce picture contrast by lowering white exposure, and to create romantic or period looks.
Schneider-Kreuznach offers different types of diffusion filter. Each technic providing its own effect. Classic Soft filter provide a precisely controlled soft image that is overlaid on a sharp, in-focus image. The HD Classic Softs are designed to allow shooting in all HD formats, including 1/2˝, 1/3˝ and 1/4˝ chip cameras without fear of artifacts. They produce the same rich In-Focus Diffusion™ as the standard Classic Soft series. While Black Frost mist flared highlights, tones down contrast while retaining rich blacks. Our Hollywood Black Magic® combines both: pleasant softening of bright highlights helps control exposure while maintaining rich blacks and colors. The Radiant Soft series expands Schneider-Kreuznach diffusion filter line, bringing the ability to give the talent´s skin a radiant, soft glow with a soothing effect on light skin imperfections and blemishes at the cost of very little blooming effect on highlights. True Net filters are the modern way to create a halo free "old romantic filmic look", given by pulling an old silk stocking on the back of your lens. They are made of/with real hosiery.
Focal length and F-Stop affect the level of diffusion. For a better control all filters come in different strength. The longer the focal length and the more light on the subject the stronger the effect.