Binoculars of size 7x50 with leather case, Made in Japan.
Binoculars of size 7x50 are traditionally dominant in naval applications. There are a couple of reasons for that: First of all, magnifications higher than 7x were difficult to use once the observer is standing on moving ground, i.e. on a rolling ship where it is almost impossible to firmly fix an object with a 10x binocular. Then, a good low-light performance is wanted for use under difficult light conditions. Finally, although 7x50 binoculars are rather heavy, this disadvantage is of little relevance on a boat where there is no need to carry it around over any longer distance.