Archived posting to the Leica Users Group, 2007/01/19
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Marc, perhaps it?s a term mainly used by Nikon. Here's some info from one Nikon site. "Binocular types : Prism binoculars Prism binoculars have a wider field of view and higher magnification than Galilean binoculars. Convex lenses are used for both objective and eyepiece lenses. The inverted image is rectified by prisms in the optical path. Two types of prism binoculars are available : 1) Roof (Dach) prism binoculars and 2) Porro prism binoculars. Roof (Dach) prism binoculars Roof prism binoculars are becoming popular thanks to their light weight and compact size. Since production and adjustment of roof prisms require the highest level of precision, optical performance differs from maker to maker. "Roof" refers to the roof-like shape of the prism. While, "Dach" is taken from the German word for "roof." Porro prism binoculars The "Porro prism" was invented by an Italian engineer, Ignazio PORRO, in 1875. It is widely used in binoculars today. Porro prism binoculars have a simple, rugged construction and form bright images." In my instance a very compact little 8 power pair with 20mm objectives. Cheers Hoppy -----Original Message----- From: lug-bounces+hoppyman=bigpond.net.au@leica-users.org [mailto:lug-bounces+hoppyman=bigpond.net.au@leica-users.org] On Behalf Of Marc James Small Sent: Saturday, 20 January 2007 11:46 To: Leica Users Group Subject: RE: [Leica] binoculars - looking for assistance At 07:51 PM 1/19/2007, you wrote: > >Empirically, I have modest Nikon binoculars on hand, one set with 20mm >objectives (dach prism) Hoppy What is a "dach prism"? Marc msmall@aya.yale.edu Cha robh b?s fir gun ghr?s fir! _______________________________________________ Leica Users Group. See http://leica-users.org/mailman/listinfo/lug for more information