The new Hoya Instant Action magnetic filter holder system allows normal screw-on filters to be magnetically mounted to the lens. Save a lot of time changing filters with the Hoya Instant Action System so you never miss that one moment again. Here's how it works: 1. screw the Hoya Instant Action Adapter Ring onto your lens - it can stay permanently on the lens. 2. screw the separately available Hoya Instant Action Adapter Ring onto your lens. 2. screw the Hoya Instant Action Conversion Ring, sold separately, onto your screw-on filter. 3. Now you can magnetically attach the filter to the lens. Since the Hoya Instant Action System is used with the filter, the entire frame will be thicker. Please note that this may cause vignetting on APS-C wide-angle lenses with a focal length of less than 14mm and on full-frame wide-angle lenses with a focal length of less than 20mm.