This is the official exposure guide for photographers using LEE Filters range of ProGlass IRND filters. Simply dial-in your metered shutter speed and then tap to calculate the adjusted exposure with any of the ProGlass IRND filters. Tap again to start a countdown timer - especially useful for very long exposures. Switch between the 2, 3, 4, 6, 10 and 15 stop filters, or if you prefer adjust the setting to show the ND values (0.6, 0.9, 1.2, 1.8, 3.0 and 4.5 ND). It's designed for fluid and precise operation in the field, with a full range of shutter speeds in 1/3 stop increments and all the controls right under your thumb.