Aspherical Lens Elements, BAK4 Porro Prisms, Fully Multicoated Optics

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The compact and lightweight navy 10x21 U-Series UP Binocular combines aspherical optical elements and BAK4 Porro prisms to deliver edge-to-edge image sharpness with a 50° angle of view. The optical elements are also fully multicoated to provide a high transmission of light. With an 10x magnification and 21mm objectives, you obtain a higher than average magnification and a compact form factor. You can easily spot your targets with a wide 5° angular field of view and quickly bring them into focus with a centre focus wheel. In addition to observing distant scenes, birds and game, the minimum focus of 9.2' allows you to study in detail close objects like animal footprints, marks or landscape features. The binocular also features a 2.1mm exit pupil, a 9.5mm eye relief, an interpupillary and a dioptre adjustments.

The binocular is very compact, lightweight, and features a single piece frame that houses objectives, which allows for a synchronised interpupillary adjustment. To accommodate eye glasses wearers, the binocular offers sliding rubber eyecups. Also included are a carrying case, a neck strap, and eyepiece covers.

Key Features

Optical Performance
  • Aspherical optical elements offer edge-to-edge image sharpness
  • BAK4 Porro prisms
  • Fully multicoated optics
  • Angular field of view: 5°
  • Interpupillary adjustment
  • Dioptre adjustment
Construction Details
  • Single main piece allows for a synchronised interpupillary adjustment
  • Contoured armouring provides a comfortable grip
  • Centre focus knob offers an easy focusing
  • Sliding rubber eyecups


Prism TypePorro
Objective Lens Diameter21mm
Angle of View(actual)
Field-of-View261' @ 1000 yd / 86.65 m @ 1000 m
Minimum Focus Distance9.24' / 2.82 m
Exit Pupil Diameter2.1  mm
Eye Relief9.5  mm
Interpupillary AdjustmentNot Specified By Manufacturer
Dioptric CorrectionNot Specified By Manufacturer
Focus TypeCentre
Tripod MountNot Specified By Manufacturer
Dimensions4.3 x 3.14 x 1.9" / 10.92 x 7.98 x 4.83  cm
Weight7.4 oz / 210 g
Pentax 10x21 U-Series UP Binocular (Navy)
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