Archived posting to the Leica Users Group, 2007/10/27
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Hence double dutch <http://www.google.com/search?hl=en&q=define%3A+double+dutch&btnG=Google+Search> but I don't know where it comes from. Phil...x Didier Ludwig wrote: >Thanks, Henning and Fred > >Btw, Fred, "dutch" is not "deutsch" (german) but the name of the language >spoken in the Netherlands. It may sound similar for anglo-saxons, but in >fact is so different that I for instance do not understand one word of >Dutch. > >Didier > > > > >>Thank you for this explanation. >>I could not have done it better, maybe in Dutch...;-)) >>Fred Hess >> >> > > > > > >>>Right, it's a linear polarizer. The M's don't >>>need circular ones. The circular ones are for >>>cameras that use semi-silvered mirrors as part of >>>their operation, either for metering such as the >>>Leica reflexes or for AF. In those cases the >>>polarized light coming through the back of the >>>filter can interfere (cross-polarize) with the >>>polarization that occurs in the semi-silvered >>>mirror and a) cause overexposure or b) not AF >>>correctly or at all. >>> >>>The circular polarizer has a so-called 'quarter >>>wave plate' at the back, which depolarizes the >>>light again. That's OK, because it's the >>>relationship of the reflection of the light off >>>non-specular parts of your subject and the >>>polarization direction of the entrance of your >>>filter that causes the effect, and if it gets >>>de-polarized after that it doesn't matter to the >>>effect on the film or sensor. >>> >>>Circular polarizers are somewhat more expensive >>>to make, but don't create a better polarization >>>effect. >>> >>>As mentioned before, 0? is the same as 180?, for either type. >>>Henning J. Wulff >>> >>> > > >_______________________________________________ >Leica Users Group. >See http://leica-users.org/mailman/listinfo/lug for more information > > >