Xavier, My test for anticipating lens/image degradation from a filter used with either strong point light source, or else strong side lighting source is; hold the filter in your hand, in an average, to fairly dark room, then look down into the surface of the filter, with any light shining on your face, if you can see a strong reflection of yourself in the surface of the filter, then it'll more than likely degrade the image a pretty fair amount. However, if you can only see a fairly faint image of yourself, then use the filter with as deep a lens hood or some other shielding device as you can and rest assured that you will get very little image degradation or loss of contrast. You understand that the above is the "Unofficial Art Tafil Test" for acceptable filters. All kidding aside, try it, because it works. I've had pretty good luck with Coated Nikon, Canon, or Minolta filters as they all pass the test, such as the Nikon L37C or L1BC filters. Just a thought, Art Tafil Oh, by the way, why not just get a used 35mm f/4 PC Curtagon, from Schnieder in Leica R, 3 cam mount? I had one for years and it did everything that I asked of it. You can get them for a few hundred dollars US.