of low temp specs. We discussed the great question of our age-yellow glass in Eastern binocs. He referenced Albrect Koehler who told him the EDF 7x40 definitely had radiation resistant glass. The 1st ocular lens was a type of flint glass that blackened with radiation. The only other substitutes were yellow tinted. The additional effect of enhanced contrast was appreciated and was a secondary but more long lasting reason. A partial answer at last!! Arnie
Kronos EWA 6x30 mm Extra Wide Angle Binoculars
Magnification: 6X Angular field of view: 12.5 degrees Eye relief: 17.5mm Resolution: 8"
Overall dimensions, mm: 60x121x173 Weight: 0.65 kg (1.43 pounds)
Review of the Kronos BPWC2 6x30 binocular, by Holger Merlitz:
Binocular List #271: 03 Oct. 2003
Subject: Russian large binocular manual
From: "Lucas, Gene" <gene.lucas@___ell.com>
Here are URLs for Russian large binoculars from the "Novosibirsk Instrument-making Plant" -- This includes some interesting diagrams, including cross-sections of the prisms and eyepieces. The site features many products, including TAL brand telescopes, night vision devices, etc. The large binoculars are shown under the category, "viewing devices".
Here is their catalog page, showing several large binoculars -- 10x80 and 15x110 models:
PNB-1 15x110 Binocular (shows diagram of optical train)
PNB-1 Manual (Shows optical train, cross section of eyepieces, mechanics, etc.)
Subject: 30x180 Russian binocular transmission
From: rab <rab5@___ring.com>
Thanks to Al Misiuk, the original "golden coatings" on my Russian 30x180 were stripped, and those surfaces recoated with MgF. This eliminated the pronounced cyan color of images and greatly increased transmission. However, without the original dichroic coating on the objective, secondary color becomes conspicuous, and reduction of acuity is apparent. Al, thankfully, is working to make some custom filters that I can attach to the eyepieces to restore the original spectral transmission. The blue-shifted spectrum combines with the undercorrected chromatic aberration of the human eye to produce a new minimum in the color curve, resulting in extreme visual acuity albeit with a cyan coloration.
Friends Dean and Roger here in Tucson transported me and the binoculars to a dark, moonless observing site where we put the 30x180 through its paces observing the summer Milky Way, the last week of August, just after the new moon had set. I took my favorite Nikon 10x70x6.5 Nikons along for comparison. Roger had a 5.5" apochromatic refractor that we also used for comparison.
It was immediately obvious that the stars were uncommonly faint in the 30x180, while they were dazzling in the Nikon and the apo refractor. My own exit pupils are doubtless no larger than 6mm. The zero distortion and high optical quality in the 30x180 made for an enjoyable experience. 30X makes many of the clusters and nebulae much more attractive than in the lower power