I have now tested the filter for several weeks. I put him committed to get the exposure time extremely to extend gradient effects for moving objects. I have used this mostly a 17-40 mm WW on a small screen - full frame camera, so when a lens with a large viewing angle. The short height of the filter appear on the screen to no vignetting. The filter used by me darkens the image evenly, as it should be. The processing is not objectionable. A few notes for use: The filter eats 99.9 percent of the incident light. Then you have to adjust during use. It can really only be photographed with a tripod. The picture and the corresponding focusing must be done prior to installation of the filter, as it actually is only dark in the viewfinder. In order to avoid incorrect exposure I had to close, so that the incident light does not affect the measurement of the viewfinder.
