HOYA Variable Density II is a density adjustable filter with an ND range from 1.5 to 9 f-stops (ND3-400). The difference with the previous HOYA Variable Density filter is the newly designed rotatable frame with convenient knob, allowing for better operation.Variable density filters are widely used because they can replace a set of solid ND filters by providing a range density that can be adjusted according to the desired exposure settings. In still shooting, variable density filters lower the shutter speed according to the photographer’s intentions when the shutter speed cannot be lowed due to camera limits. Variable density filters can also increase the amount of boke when shooting in the over-lit conditions, thus, preventing the image from overexposure.In video shooting, it is fundamental to keep the shutter speed fitting the frame rate setting. That is, to keep it equal to double the frame rate for optimal results. This is because, unlike still photography, an excessively fast shutter speed may create a jarring effect and produce afterimages that will not look good in the final video.By using variable density filters, the shutter speed can be adjusted to the proper value to get that natural and smooth looking motion requested in video footages.Be aware that when the filter is attached to the lens, the lens cap size becomes one size bigger. So if your lens has a filter thread size of 77mm, you will require an 82mm lens cap. The widened front filter frame has been designed on purpose to avoid vignetting.
