Explore Scientific BT-70 SF Large Binoculars with 62 Degree LER Eyepieces

Explore Scientific calls a giant binocular a double refractor telescope: the BT-70 SF has two 70mm achromatic objectives, one complete telescope with its full light grasp for each eye, at a 45° viewing angle for fatigue-free observing even with the binocular tilted steeply. The two 62° 20mm eyepieces it comes with give 20x and a 3.1° field, and any 1.25-inch eyepiece fits in their place.

Key Features

• Two 70mm achromatic refractors. 400mm focal length at f/5.7, with Enhanced Multilayer Deposition (EMD) coatings on all optical surfaces.
• Viewing with both eyes. Explore Scientific says two-eyed viewing is relaxed, shows objects almost in relief, makes the finest details easier to see and keeps the eyes from tiring quickly.
• 45° viewing angle. Explore Scientific designed it for fatigue-free use, even with the binocular tilted steeply toward the sky.
• Two 62° 20mm LER eyepieces included. 20x with a 3.1° field, 15mm of eye relief and soft fold-down silicone eyecups. The eyepieces are waterproof and argon-filled.
• Interchangeable 1.25-inch eyepieces. Any 1.25-inch (31.7mm) eyepiece fits. Explore Scientific suggests its 62° and 82° series from 8 to 26mm, about 15x to 50x in this binocular. Brass compression rings hold each eyepiece without tilt.
• Filters in pairs. Explore Scientific's 1.25-inch screw-in color and nebula filters thread into the eyepiece barrels, one for each eye.
• Individual helical focusing. Each eyepiece focuses on its own, and the eyepiece spacing adjusts from 54 to 76mm.
• Sealed magnesium body. Sealed to IPX6 and filled with nitrogen, so the inner optics do not fog in bad weather.
• Extendable dew caps. Pull them out in humid or cold air to keep dew off the objectives and block stray light from the side.
• Metal carrying handle at the center of gravity, for carrying the binocular and holding it securely while you mount it.

Ideal For

• Astronomers who observe with both eyes: globular clusters, glowing gas nebulae, the Moon's craters and the planets, the targets Explore Scientific names for its giant binoculars.
• Daytime observers watching distant wildlife, ships and aircraft, which Explore Scientific says the series shows in detail.
• Twilight and night observers: Explore Scientific calls the series especially suited to dusk and night.

Accessories & Compatibility

• Mounting. The tripod foot takes a photo tripod on two 1/4-inch threads or one 3/8-inch thread, and Explore Scientific strongly recommends a stable tripod rated for the load. Its U-Mount with field tripod was designed for the BT series and is rated to 12 kg (26.5 lb); the BT-70 SF weighs 7.5 lb.
• U-Mount. Adjustable friction on both axes, and Explore Scientific says the mount's solid build and large stainless steel tripod keep vibration to a minimum, even at high magnification.
• Siblings. For more aperture, the BT-120 SF has 120mm objectives and weighs 8.3 kg (18.3 lb), and the BT-150 ED has 150mm objectives of extra-low dispersion (ED) glass.