Archived posting to the Leica Users Group, 2007/01/19

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Subject: [Leica] binoculars - looking for assistance
From: hoppyman at bigpond.net.au (G Hopkinson)
Date: Fri Jan 19 18:20:33 2007
References: <82c9dd70701180437w53164f0as5cdf7876ee4dc0c1@mail.gmail.com><9b678e0701181822k1af49093j513fc3c8d90d4667@mail.gmail.com><200701190336.l0J3aXUx089592@server1.waverley.reid.org><9b678e0701191514q334daf02r9845b671a24a73cd@mail.gmail.com><200701192327.l0JNRwUR010458@server1.waverley.reid.org><001201c73c26$4d84a170$6501a8c0@asus930><p06230911c1d710bc663e@[10.1.16.144]><001c01c73c2d$27411500$6501a8c0@asus930> <200701200152.l0K1qLoW073868@server1.waverley.reid.org>

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!



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Replies: Reply from marcsmall at comcast.net (Marc James Small) ([Leica] binoculars - looking for assistance)
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