Designed for both astronomical and terrestrial use, Pentax's 8x40 /10x50 /12x50 /20x60 SP S-Series WP Binocular can be used with confidence in all weather and conditions. The large oversized 40mm (8X40) /50mm (10X50, 12X50) /60MM (20X60) objectives are fully multicoated to reduce reflection and maximize light transmission through the entire optical path. Utilizing the traditional porro prism configuration gives scenes a rich depth of view for an immersive observation experience and provides a comfortable feel in the hand with a lot of surface area to maintain a sure grip. The large objectives and coatings maximize the amount of light getting to the user's eyes for exceptional low-light capabilities, and its high 10x magnification provides an immersive observation experience. Complementing the optical performance are construction details made for the trail. The optical tubes are nitrogen-filled and O-ring sealed for fogproof performance and to make them submersible to as much as 3.3'. The binocular sports a generous 20mm eye relief and the fold-down eyecups seal against the ocular cavity to block stray peripheral light which can dim images and effect night adjusted vision for 10x50, 12x50 & 20x60. Optical Performance: 8x 10x 12x 20x magnification BAK4 porro prism optical path Anti-reflection fully multicoated optics Use and Handling: Closed bridge configuration Large knurled center focus wheel Right-eye diopter adjustment Fold-down rubber eyecups seal against ocular cavity and block stray peripheral light Construction Details: Rubberized armoring protects against impacts and provides slip-resistant grip Nitrogen-filled, fogproof and submersible to 3.3' (1m) Internal focusing system helps to maintain waterproof seals Tripod mountable with optional adapter Specification: Prism Type: Porro Magnification: 8x 10x 12x 20x Objective Lens Diameter: 40 mm /50 mm /50 mm /60 mm Angle of View: 6.3 (8x40) / 5.0 (10x50) / 4.2 (12x50) / 2.2 (20x60) Field of View: 330.7' @ 1000 yd / 110.2 m @ 1000 m (8x40) 262.5' @ 1000 yd / 87.5 m @ 1000 m (10x50) 220.5' @ 1000 yd / 73.5 m @ 1000 m (12x50) 115.5' @ 1000 yd / 38.5 m @ 1000 m (20x60) Minimum Focus Distance: 74.9' / 22.8 m (8x40) 117.3" / 3 m (10x50) 117.3" / 3 m (12x50) 58.2' / 17.7 m (20x60) Exit Pupil Diameter: 5.0 mm (8x40) 5.0 mm (10x50) 4.2 mm (12x50) 3.0 mm (20x60) Eye Relief: 20 mm / 21mm (20x60) Interpupillary Adjustment: Not Specified by Manufacturer Dioptric Correction: Not Specified by Manufacturer Focus Type: Center Tripod Mount: Yes (Adapter Optional) Dimensions: 7.0 x 5.4 x 3.0" / 17.8 x 13.7 x 7.6 cm (8x40) 7.2 x 7.0 x 3.1" / 18.3 x 17.8 x 7.9 cm (10x50) 7.2 x 7.0 x 3.1" / 18.3 x 17.8 x 7.9 cm (12x50) 8.8 x 7.7 x 3.4" / 22.4 x 19.6 x 8.6 cm (20x60) Weight: 31.8 oz / 901.5 g (8x40) 37.4 oz / 1060.3 g (10x50) 38.1 oz / 1080.1 g (12x50) 49.4 oz / 1400.5 g (20x60) Content: Pentax 8x40 /10x50 /12x50 /20x60 S-Series SP WP Binocular Neck Strap Carrying Case with Strap 2 x Objective Lens Caps 2 x Eyepiece Caps