The standard glass used in Hoya UV filters is L39. This means it blocks UV at 3900 angstroms or 390 nanometers. Nikon used to sell L37 glass. If you really want to ensure less UV the best are Hoya Pro Series filters which use L41 glass, Kenko also has a L41 label on some of the premium filters (Kenko is made/owned by Hoya). Above this the glass changes color and is mean for aerial photography. B+W has a UV415 filter which is slightly yellow, and WILL cause a slight color shift if used at sea level. If you want to know if you have a decent UV Filter, place it against a fluorescent light and you should see the color change to a slight yellow tint. I use a small ligh box and lay them on that. You can instantly tell if they are junk or not.
Peter K * **** ******* *********************************************************** * For list instructions, including unsubscribe, see: * http://www.a1.nl/phomepag/markerink/eos_list.htm ***********************************************************
