The Hoya 67 mm Variable Neutral Density Filter provides a convenient way to maintain exposure control by being able to vary the amount of light entering the camera by 1.5 to 9 stops (0.45 to 2.7 density for Cine use). The precision built-in double ring design allows the outer ring rotates to control amount of neutral density effect anywhere within the 1.5 – 9 stop range. This double-ring design is also thin to reduce the likelihood of vignetting with wide-angle lenses. This control allows for many special effects such as being able to control depth of field by using a wider aperture or create or control motion blur by being able to choose just the right slower shutter speeds for perfect blurring.
The HOYA Variable Neutral Density filter can take the place of a range of graded ND filters which saves money by only needing to buy one filter and saves time on location or on set by not needing to change filters constantly to change the effect, just turn the right to get the effect you want. The HOYA Variable Neutral Density filter puts you in control.
Variable Neutral Density filters, and ND filters in general have these main uses:
Slow down shutter speed for motion blurring effects like waterfalls, cars or blurred panning movement to make the subject stand out from the background.
Allow wider apertures to be used to decrease depth-of-field, literally focusing more attention on the subject.
Allow higher ISO films to be used in brighter lighting conditions
Allow cine/video cameras, which have a fixed shutter-speed range, to film on brighter lighting conditions such as the beach or in snow on a sunny day.