Original British WWII Barr and Stroud Field Rangefinder in Original Transit Chest Issued to Royal Danish Army as Afstandsmåler M/54 Original Items

Original Item: Very few available. This is a genuine WW2 manufactured rangefinder developed by Barr & Stroud Limited who was a pioneering Scottish optical engineering firm, initially formed in 1913 in Glasgow. They played a leading role in the development of modern optics, including rangefinders, for the Royal Navy and for other branches of British Armed Forces during the 20th century.

The Rangefinder was sold and reissued to the Danish army during the cold war and is marked as such. This example is in excellent condition, fully functional and contained in the original wood transit chest. The data plate on the transit chest reads:

(CROWN)

HMAK

Afstandsmåler M/54

The data plate on the rangefinder reads:

(CROWN)

FKF

Afstandsmåler M/54

Basis 80cm. Forstørring 14x

Nr. 767

The range finder measures 36” in length and is light enough for a single man to use with ease. The transit chest measures 39 x 8¼ x 8¼”.

The coincidence rangefinder uses a single eyepiece. Light from the target enters the range finder through two windows located at either end of the instrument. At either side the incident beam is reflected to the center of the optical bar by a pentaprism. The optical bar is ideally made from a material with a low coefficient of thermal expansion so that optical path lengths do not change significantly with temperature. This reflected beam first passes through an objective lens and is then merged with the beam of the opposing side with an ocular prism sub-assembly to form two images of the target which are viewed by the observer through the eyepiece. Since either beam enters the instrument at a slightly different angle the resulting image, if unaltered, will appear blurry. Therefore, in one arm of the instrument a compensator is adjusted by the operator to tilt the beam until the two images match. At this point the images are said to be in coincidence. The degree of rotation of the compensator determines the range to the target by simple triangulation. Coincidence rangefinders made by Barr and Stroud used two eyepieces, and may be confused with stereoscopic units. The second eyepiece showed the operator a range scale so the user could range and read the range scale simultaneously.

This is a fantastic piece of British & Danish military history, ready for further research and display!