Tiffen 82mm Variable Neutral Density ND Filter Gray The Tiffen variable ND filter is a unique and flexible tool, affording you the convenience of using several neutral density filters in one Neutral density filters reduce the amount of light going through the lens into your camera. By reducing the light you are able to achieve the following:• Allows the use of slow shutter speeds, with high speed films or digital cameras, to record movement/image blur in subjects such as waterfalls, clouds or any fast moving subject • Gives you full control over your depth of field. You are able to decrease depth of field by using wider apertures, which helps separate subjects from their background (subject matter in focus while your background is blurred) • Allows you to shoot high speed film (above ISO 400) in bright outdoor situations by reducing effective ISO • Enables cine and video cameras (which have fixed shutter speeds) to film subjects such as snow, sand or other bright scenes which could cause overexposure Primarily used for controlling depth of field and exposure, the variable ND is easy to use, small, lightweight, and does not require additional accessories. Neutral density filters reduce the amount of light going through the lens into your camera. By reducing the light you are able to use of slow shutter speeds, with high speed films or digital cameras, to record movement/image blur in subjects such as waterfalls or any fast moving subject. It also gives you full control over your depth of field.The Tiffen variable ND filter operates on the same principle as a circular polarizer - rotate until you reach your desired effect. Provides 2 to 8 stops of light. Pick up from New Barnet, or High Barnet or Cockfosters tube stations