Explore Scientific BT-70 SF Giant Binoculars

Description

Operating with 70mm objective lenses and an expansive 62-degree apparent field of view at 20x magnification, the Explore Scientific BT-70 SF Giant Binoculars deliver high-contrast stereoscopic observation for astronomical sky sweeps and long-range landscape monitoring. Equipped with supplied 20mm 62-degree LER eyepieces, this large-aperture instrument produces a 3.1-degree actual angle of view, a balanced 3.5mm exit pupil, and 15mm of eye relief for resolving lunar maria, planetary disks, and distant mountain vistas across varied field conditions.

The optical system features 70mm semi-apochromatic (SF) doublet objective lenses with a 400mm focal length, paired with oversized BaK-4 Porro prisms and broadband fully multi-coated surfaces for optimized light transmission and color fidelity. Measuring 370 by 213 by 122mm (14.6 x 8.4 x 4.8 inches) and weighing 3.4 kg (7.5 lbs), the chassis is cast 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 aluminum 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-70 SF Giant Binoculars

Designed for amateur astronomers and panoramic terrace observers, this 70mm giant binocular combines semi-apochromatic doublet optics with 45-degree angled oculars. Its broadband multi-coated lenses and oversized BaK-4 Porro prisms produce bright, high-contrast imagery of open star clusters and planetary surfaces. The nitrogen-filled IPX6 water-resistant chassis mounts securely on tripods and alt-azimuth fork heads via its dual-threaded mounting plate.

• 20x standard magnification using supplied 20mm eyepieces paired with light-gathering 70mm objective apertures
• Porro prism optical architecture utilizing oversized BaK-4 optical prisms for complete field illumination
• Semi-apochromatic doublet objective lenses delivering sharp color correction across a 400mm focal length
• Wide 62-degree apparent field of view with an actual angular field of 3.1 degrees at 20x
• Comfortable 15mm eye relief and 3.5mm 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

70mm Semi-Apo Doublet Glass & BaK-4 Porro Prism Optics

The 70mm objective lenses gather ample photon volume, generating a 3.5mm exit pupil that renders celestial targets with sharp contrast against dark background skies. Semi-apochromatic doublet optical elements suppress chromatic aberration across high-contrast edges, such as the bright lunar limb and planetary contours. Oversized BaK-4 Porro prisms provide complete optical throughput to the ocular holders, preventing edge vignetting and maintaining illumination across the entire 62-degree apparent field.

IPX6 Nitrogen-Purged Housing & 45-Degree Viewing Ergonomics

The magnesium-aluminum alloy chassis keeps total tube mass to 3.4 kg, providing structural rigidity to maintain factory collimation alignment while remaining easily transportable for dark-sky excursions. 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 retention
• 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 & Inclusions

The Explore Scientific BT-70 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-70 SF giant binocular body, pair of 20mm 62-degree LER eyepieces (20x), extendable dew shields, objective lens covers, eyepiece caps, and heavy-duty transport case.