Explore Scientific BT-120 SF Giant Binoculars

Description

Operating with massive 120mm objective apertures and a 62-degree apparent field of view at 33x magnification, the Explore Scientific BT-120 SF Giant Binoculars deliver high-contrast stereoscopic observation for deep-space astronomy and ultra-long-range landscape surveillance. Equipped with supplied 20mm 62-degree LER eyepieces, this large-aperture instrument produces a 1.8-degree actual angle of view, a balanced 3.6mm exit pupil, and 15mm of eye relief for resolving lunar rilles, planetary disks, and faint star clusters across the night sky.

The optical system incorporates 120mm semi-apochromatic (SF) doublet objective lenses with a 660mm focal length, paired with oversized BaK-4 Porro prisms and broadband fully multi-coated surfaces for optimized light transmission and color fidelity. Measuring 654 by 290 by 156mm (25.7 x 11.4 x 6.1 inches) and weighing 8.3 kg (18.3 lbs), the chassis is fabricated from lightweight magnesium-aluminum alloy and sealed to IPX6 water-resistant standards with dry nitrogen gas filling to prevent internal fogging. Eyepiece barrels are angled at 45 degrees to facilitate comfortable high-elevation observing, controlled by independent helical focusers with brass compression rings that accept standard 1.25-inch eyepieces, an interpupillary distance range from 54mm to 76mm, sliding metal dew shields, an integrated carry handle, and a bottom mounting foot with 1/4-20 and 3/8-16 threaded sockets.

Key Features of Explore Scientific BT-120 SF Giant Binoculars

Designed for amateur astronomers and long-range border watchposts, this 120mm giant binocular combines semi-apochromatic doublet optics with 45-degree angled viewing comfort. Its broadband multi-coated lenses and oversized BaK-4 Porro prisms deliver bright, high-contrast views of deep-sky nebulae and planetary surfaces. The nitrogen-filled IPX6 water-resistant chassis mounts securely on heavy-duty tripods and fork heads via its dual-threaded mounting plate.

• 33x magnification using supplied 20mm eyepieces paired with colossal 120mm objective apertures
• Porro prism optical architecture utilizing oversized BaK-4 glass blocks for full field illumination
• Semi-apochromatic (SF) doublet objective lenses delivering sharp color correction across 660mm focal length
• Wide 62-degree apparent field of view with an actual angular field of 1.8 degrees at 33x
• Comfortable 15mm eye relief and 3.6mm exit pupil with soft rubber eyecups on 1.25-inch oculars
• Independent helical eyepiece focusers with brass compression rings for standard astronomical oculars
• Airtight nitrogen-purged magnesium-aluminum chassis certified to IPX6 water-resistant standards
• Integrated carry handle and bottom mounting foot with 1/4-20 and 3/8-16 threaded tripod sockets

120mm Semi-Apo Doublet Glass & BaK-4 Porro Prisms

The 120mm objective lenses gather extensive photon volume, generating a 3.6mm exit pupil that renders faint celestial targets with remarkable clarity against dark background skies. Semi-apochromatic doublet optical elements suppress chromatic aberration across high-contrast edges, such as the lunar limb and bright planetary features. Oversized BaK-4 Porro prisms ensure complete light throughput to the ocular holders, preventing edge vignetting and maintaining illumination across the entire 62-degree apparent field.

Magnesium-Aluminum Chassis & 45-Degree Viewing Ergonomics

The magnesium-aluminum alloy chassis keeps total tube mass to 8.3 kg, providing structural rigidity to maintain factory collimation alignment while remaining portable for dark-sky field expeditions. The 45-degree angled ocular orientation allows observers to study zenith celestial targets without experiencing neck fatigue. Retractable metal dew shields slide forward to block stray peripheral light and prevent dew formation on the objective lenses, while dual independent helical focusers permit precise focal adjustments for each eye.

• Dual independent helical focus collars with brass compression rings for secure eyepiece clamping
• Nitrogen-purged IPX6 water-resistant chassis engineered to withstand heavy outdoor dew and rain
• Built-in 45-degree angled eyepiece receptacles and integrated top handle for safe transport and setup

Explore Scientific Manufacturer Warranty & In-Box Inclusions

The Explore Scientific BT-120 SF Giant Binoculars are backed by the Explore Scientific limited warranty covering optical and structural components against manufacturing defects. The complete factory package contains the Explore Scientific BT-120 SF giant binocular body, pair of 20mm 62-degree LER eyepieces (33x), extendable dew shields, objective lens covers, eyepiece caps, and heavy-duty transport case.