The Hoya Variable Density filter uses two polarizing layers to control the amount of light that passes through the filter and into the camera lens. At it's minimum effect the filter passes 1/3 of the light in a scene. That is equal to 1.5 stops on the aperture or shutter speed. At it maximum effect the filter passes just 1/400 of the light in a scene. That is equal to 9 stops on the aperture or shutter speed.
After the filter is mounted on the lens, turning the filter ring between "Min" and "Max" can greatly control the amount of light entering the lens. With the Hoya Variable Density filter it is possible to shoot with fast lenses like 50mm f/1.4 lenses wide open at f/1.4 in full sun for a very shallow depth of field. Or, to slow down the shutter speed to where the shutter can be open for several seconds in full sunlight. This is enough to create artistic blurring shots of motion on water, cars, people or almost anything that moves. The creative possibilities are endless.
The Hoya Variable Density filter uses high-quality optical glass from Hoya Corporation, the worlds largest optical glass manufacturer and is available in sizes 52mm to 82mm.
For best results Hoya recommends using a tripod when photographing at slow shutter speeds.
Reviewed by 1 customers
Didn't want to buy a whole set of neutral density filters for the 82mm Tammy 24-70 (already have a full set of 77mm). I like the overall quality of Hoya filters, so I spent the extra to get this one. First, it gives me right at 10 stops of reduction without running into the dreaded "X" issue. Image quality is excellent, color seems a touch richer, VERY pleasant. ONLY down side I can find on this filter is that it lacks threads to attach a lens cap to. For street shooters like me, that is a major issue that Hoya needs to correct. How I use the variable filter: Rather than attach a density filter and adjust settings for exposure, I work a bit backwards- I set the camera to the desired settings, then turn the filter until the exposure meter shows a proper exposure. Not so easy to work with for long night exposures, but great for working in the sun. Just remember that the scale on the filter does NOT give particular measured settings, but rather simply indicates max and minimum filtration. The filter works on the cross-polarization principle, so progression of light reduction is not even -that's why the scale can't give particular settings like .3 or .9.