Archived posting to the Leica Users Group, 1998/01/12
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]At 04:37 PM 1/12/98 -0800, you wrote: >OK .............. let us empty the whole can of worms onto the table. > >I was told by someone ( I really forget who ) that a circular polarizer was >designed to work with the new ( 10 yrs.-? ) autofocus lenses and had >nothing to do with the metering system. Further, that a linear polarizer >would work just fine on the new lenses but that you might have a focusing >problem and should probably use them in manual focus mode if using a linear >polarizer. > >Cheers, >David Medley David, For Leicas, it's the fact that a portion of the incoming light is directed through a partially silvered mirror (the SLR mirror), for exposure determination. The partially silvered mirror (beam splitter) acts as a polarizer and will give incorrect exposure readings with a linear polarizer. If someone told you that circ. polarizers were for autofocus lenses, I guess it could be true. Perhaps one of the camera makers uses a polarized beam splitter to extract focus information. I've never heard of this though. Leica publishes the reason for circular polarizers. Jim