Breathe new life into your Pentax 645-mount lens by using it on a fresh Nikon F-mount camera with the Fotodiox Vizelex ND Throttle Adapter, which even features a built-in variable ND filter for added control over your exposure. The integrated ND filter of the Vizelex offers a 0.3 to 2.4 filter factor, which translates into a wide range of 1 to 8 stops. This makes the adapter ideal for videographers and photographers who may want to make quick adjustments to their filtration throughout the day. The ND filter can be used to lengthen the shutter speed or use larger apertures when working in bright sunlight. Also, the placement of the filter within the adapter means that switching lenses does not require users to fiddle with additional filters and it will even work with lenses that do not have a filter thread. Additionally, this filter is constructed of both brass and aluminum for a durable construction and precise fit with your equipment that guarantees infinity focus.