Japanese 18.8 or 20 x 150 mm Binoculars
The 150 mm Japanese models are even larger and were manufactured with both double and triple element objective lenses, the latter of the Cooke type. Single magnification instruments were provided in 18.8x and 20x with a 3 degree real field, and 25x with 2.4 degree real field. A dual magnification turret model was also manufactured with magnifications of 20x and 30x and real fields of 3 degrees and 2 degrees. Apparent field angles are 60 degrees.