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Gordon Rayner
professor emeritus
Reged: 03/24/07
Posts: 506
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Re: huge 110mm russian binoculars (pic)
05/24/08 04:11 PM
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Re: prism in Novosibirsk 15 x 110 and prism in Busch 10 x 80 with 45 deg inclination from World War II ( Holger Merlitz). I have never been inside the 15 x 110,nor do I have a specimen, but have been inside many Busch design 10 x 80, and have a copy of its plans (via a WW II Leitz file, about 100 pages,which I found after extensive research, fragments of which appear in the Seeger book(without credit)). The roof angle tolerance in the Busch design's Schmidt prism is 10 seconds of arc. While the 10 x 80 offsets the beam( center of outgoing beam to the eyepiece is offset laterally with respect to the center of the beam entering the prism from the center of the objective lens), I believe that the roof splits the light cone (asymmetrically). I have seen barely detectable( at 10x) double images in one or two Busch built (cxn) 10 x 80, but never in a Schneider (dkl) nor in a Leitz (beh). There exist 20 x 80 which used the same eyepiece as the Zeiss 12 x 60. Were those prisms made to a tighter roof tolerance?
The 15 x 110 prism, which is not a Schmidt prism, seems to have a much greater offset laterally, so much that one can consider the possibility that the roof line does not split the cone ( Amici II), with 30 deg overall deviation of the line of sight, in the case of the 15 x 110 from Novosibirsk. Any 15 x 110 split, if it exists, is very asymmetic. When a roof prism does not split the beam, the roof angle tolerance can be much looser. Errors in the roof angle, in this case, result in image rotation, rather than double images.
With all the oil money in Siberia , one can hope that someone will invest in the optical factory in Novosibirsk, to diversify local industry, and improve the mechanisms and the glass.
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