Cameras and Lenses
Question about Zeiss Turact with tickmarks and unusual eyepiece
I own a 1918 vintage Zeiss Turact 8x24 pair of binoculars that I inherited from a family member, and I am curious about a couple of features in it.
Question #1: Tickmarks.
On the bottom, the binoculars have two metal plates showing, respectively, a standing soldier and a soldier on horseback. These figures have horizontal lines ("tickmarks") that start at zero at the top of the head in both figures, and end at 1300 for the feet of the standing soldier and at about 1800 for the hooves of the horse. (See http://home.comcast.net/~dapena/bin...s/tickmarks.jpg ) Since these binoculars were designed for military use, I suspect that the tickmarks serve to estimate the distance to a standing person or to a person on horseback, but I can't quite figure out how the method worked. The tickmarks are spaced at the same distance apart for every 100 units. All the methods that I can speculate would require a non-linear scale, so they don't fit.
Question #2: Eyepiece.
The right eyepiece has an extra lens that can be brought in by turning a little wheel on the eyepiece. (See http://home.comcast.net/~dapena/binoculars/eyepiece.jpg ) My picture shows this extra lens half-way into place. When the extra lens is in place, the image stays as sharp as before, but you now see an equally sharp ghost image next to the original image, like with the mineral called "Iceland spar". (You see double.) If you rotate the extra lens, the ghost image rotates around the original image.
I would appreciate any responses to my questions #1 and #2. Maybe they are related??
Hello Suso,
The figures and markings work in place of a reticule, graticule in the UK. Let us say, that the user sees an upright and complete soldier, than the distance is the maximum. Should the observer see only a head, then it would be the nearest distance. Similarly, it works with the cavalryman on horseback. It works as a rough and ready rangefinder, suitable for setting the sights on a rifle. Such engravings and distance markings are typical of some early WWI French binoculars.
The extra lens may have allowed for examination of a suspicious object: rotating might have revealed camouflage or details. That is a guess.
Happy collecting,
Arthur Pinewood 