The writer may want to try I Miller in Philadelphia-whom I alluded to in the last few issues of your missive for replacement eyecups. The old military glass should be right up their alley.
I've sought for sometime one of the russian wide field 8x30s without luck. Am planning on getting one of the 6x30s soon. Will let the group know about them when I do. Arnie
Subject: B & L in U.K.
From: Stephen Sambrook <scsambrook@___co.uk>
The following might interest Keith Shackleton . . . Bausch & Lomb Military Stereo binocs: The Bausch & Lomb Military Stereo binocs made to British contracts in 1915 are unusual in that inspection and British serial-marking was done at the factory rather than at Woolwich Arsenal in London (a bit like the Russian-contract Smith & Wesson revolvers in the late 19th century, where the foreign state customer had a resident inpsector or inspectors at the US factory). I wonder if the 'S 1' numbers on the B&L glasses are part of the factory serial numbering sequence, or whether a block of serials was specified in the British order ? Do any B&L collectors have any information on this? As to a replacement eyecup, I think there may be more than one pattern. Maybe the easiest way is to look for another scrap binoc and try to cannibalise it . . . Best wishes Stephen Sambrook
PS - is a pair of binoculars really four telescopes ? Or should we talk about a pair of monoculars ? And how many Angels can stand on the head of a pin ? Cheers Stephen
Subject: Bakelite Eyecups
From: Paul Johnston <pjohnston@___ond.com>
Bakelite can be machined but requires polishing with jewelers paste to give a smooth finish.
Subject: Glass, collimators
The prism glass and its effect on aberrations is discussed in detail in Chapter A8 of vol. I of the Willmann-Bell reorganized and edited Amateur Telescope Making books originally edited by Ingalls and published by scientific american. The equations in the Scientific Am. were misprinted. I was having problems with them, so called Selby, who dug up and sent to me his original, which I sent to both publishers. So I got a minor credit.
As we know, Hanna has a big binocular section. Does his second method, on p. 411 of the Willmann-Bell vol 2, qualify as "tail of arc? I have used both. For rapid sorting to see which barrel is the worst, a swingless method method is desirable, obviously particularly of the hinge is stiff or inaccessible, as is so often the case these days. If one can directly see the point at whic h the hinge axis intersects a plane at infinity, rather than inferring it from tail-of - arc swinging, things are faster and simpler, and more than adequately accurate. One can use the front of the.binocularas approximately orthogonal to the hinge axis, an assumption implicit in the Fuji UBMM folded reflecting projection collimation rig. A menu of appropriate devices for this or hinge riding in vee blocks is available in optical tooling devices(industrial surveying), weapon or camera sights, green laser pointers, etc. Of course , a comparator to view the hinge axis intersection at infinity simultaneously with the view through one barrel of the binocular, is required.