on the smaller model 1892 canet gun and anti-aircraft batteries wide zeiss stereoscopic rangefinders were used. maximum distance that could be reliably measured with three meter rangefinders was , while the maximum range of the six inch guns was . a single rangefinder was used by the commander of the artillery in a central fire control station at kuivasaari. six meter rangefinders were also planned for the 10 inch batteries later in the war but never obtained.