The Hoya Variable Neutral Density Filter is a solid variable neutral density filter providing an exposure reduction of about 1.5 stops (ND3) to 9 stops (ND400). The 0.45 to 2.7 density creates a darkening of the entire image, allowing you to photograph with a wider aperture or slower shutter speed than would normally be required. The degree of density is easily controlled by rotating the front filter ring, helping you to predetermine the additional exposure length required. By slowing your exposure time or increasing your aperture, you are able to control depth of field and convey movement more easily.
This filter is constructed from optical glass to maintain image clarity and is set within a slim profile aluminum ring, which helps to reduce the likelihood of vignetting when used on wide-angle lenses, and does not feature front threads.
Neutral density (Nd) filters can reduce the intensity of light without appreciably changing its color. Classic nd filters have different f-stop reduction numbers and transmittance thus generated can be applied for different shooting conditions, such as portraiture, water falls, etc.
The index marks on the filter let you know exactly the amount of reduction at a glance, giving you clear and precise shots at whichever density you are using.
1) neutral density can be adjusted from nd3 to nd400. It is easy to create different neutral density by rotating the ring.
2) apply slow shutter speed under strong sunlight exposure.
3) able to create shallow depth of field easily under bright daylight
4) suitable for waterfalls, streams, waves, cloud, human/vehicle traffic etc.