Archived posting to the Leica Users Group, 1997/08/19
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]At 11:27 PM 8/18/97 -0700, you wrote: >At 11:56 PM 8/18/97 -0600, you wrote: >>At 08:25 PM 18/08/97 -0400, you wrote: >>> >>In addition to Jim's excellent posting, I can add that the B&W circular >>polarizers delaminate. This becomes noticeable first near the ring, and >>then gradually migrates inwards. >> >>-GH > >The B+W Kaesemann circular polarizer will not delaminate. At least I've >never had one delaminate. B+W states that the Kaesemann is manufactured to >tighter standards and hermetically sealed which should keep it from >delaminating. One would hope for the price! > >Jim > Polarizers do not need single coating. The nature of polarized light makes single coating moot. Multicoating can be of some help if shooting directly into a very bright light source, such as the sun, but then why use a polarizer. It will do more harm than good. Polarizers work when the angle of polarization is in a range of 30-40 degrees. Not near zero degrees. Polarization also makes green foliage green, reducing the reflection of the blue or white sky from the foliage. Windows, cars, sky, and water can benefit from a polarizer, depending upon the direction and type of the main light source. A polarizer is nearly useless when the light source is directly in front or directly in back. Generally speaking polarizers do not need to be coated, multi or otherwise. The situation under which you use a polarizer and the nature of polarized light dictates that coating is not necessary. So the Kaesemann circular polarizer is the best available and will, because of the edge sealing, not delaminate. And, because of using select foils and specially prepared glass, will not cause problems with long fast or Apo lenses. TIMHO. Jim