We designed the system so that the filter remains in the filter holder and is attached/detached as an assembly. The filter holder bayonets onto camera with less than 90° of rotation to the locked position. The low tension locking system assures that the lens barrel won't be harmed by over-enthusiastic tightening (or loosening) of the filter. The ability to quickly change the filter without having to thread/unthread should appeal to filter users. You'll find that you're more likely to use your filters when they can be mounted and removed this easily. You may use 2 filters at a time, with no vignetting at any focal length.