The Tiffen 4 x 5.65" 0.4 ND Filter is a solid neutral density filter providing a 1.3 stop exposure. This 0.4 density creates a darkening of the entire image, allowing you to photograph with a wider aperture or slower shutter speed than normally required. By slowing your exposure time or increasing your aperture, you are able to control depth of field and convey movement more easily. Neutral density filter does not affect the coloration of the image and is ideal for pairing with other filters.
This filter is 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.