Kowa BD 10×42 XD

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Objective diameter:  42 mm
Magnification:  10 x
Exit pupil: 4.2 mm
Eye relief (acc. to spec): 18 mm
Usable eye relief (measured from rim of eyecup): 12.5 mm
IPD:  57 – 75 mm
RFOV:  6.2  degrees = 108 m
AFOV (measured, rounded): 59 degrees
Minimum focus distance (measured): 1.15 m
Focus type: CF (direction of rotation from close to infinity: < anticlockwise)
Degrees of rotation of focus wheel from 3m to infinity (measured): 185 degrees
Range of diopter adjustment (estimate): +/- 6 dpt*
Excess travel of focus wheel beyond infinity position (estimate): 6 dpt*
Prism system:  Schmidt-Pechan
Waterproof: yes
Weight (measured, with eyepiece cover and strap): 751 g
Made in: China
*range of diopter adjustment not affected by position of focus wheel



This is one of the smallest and lightest 10x40s currently on the market. One of the elements of the objective lenses is made of “Prominar XD” low dispersion  glass (Kowa sometimes calls this “Fluorite” glass), which is also used in Kowa’s top line of instruments (Genesis binoculars, Highlander BT, spotting scopes) and is supposed to minimize the inherent chromatic aberration (CA). Due to the very short build of the binocular, which generally can lead to more pronounced aberrations, the goal of reducing CA is only partially achieved, but overall, the image is clear, bright and shows quite good contrast. The transmission ratio of the central focusing mechanism is faster than in many other 10x40s.



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