Neutral Density (ND) filters can reduce the intensity of light going in to your camera when shooting during the day so you can shot at a VERY shallow depth of field. Classic ND filters have different f-stop reduction numbers so you can plan for different shooting conditions, such as portraits, water falls, the beach… whatever. The bad side… you’ll need several filters with you just in case you need to block out more light.
Variable ND Faders are compact and is an all-in-one neutral density fader filter that adjusts the amount of light reduction with just the twist of your wrist. These are able to adjust neutral density freely from ND2 to ND400. With Tiffen ND filters… you’ll only need one and you’re ready to go.
* Neutral density can be adjusted from ND2 to ND400. It is easy to create different neutral density by rotating the ring.
* Apply slow shutter speed under strong sunlight exposure.
* Large aperture is available to create depth of field easily.
* Suitable for dynamic screen, waterfalls, streams, waves, etc.
* Index marks on the edge of filter for exact adjustment.
The one that I have is a Tiffen 77VND 77MM VARIABLE ND FILTER and can be found HERE.