Explore Scientific BT-120mm ED Giant Binocular

Twin 120mm ED Objectives: Apochromatic Views of the Deep Sky

At the heart of the BT-120mm ED are two massive 120mm air-spaced triplet objectives. This immense aperture gathers significant light, resolving faint details in distant galaxies and revealing the delicate structures within nebulae like the Veil Nebula (NGC 6960). The use of premium ED glass virtually eliminates chromatic aberration, the false color fringing seen around bright objects in simpler designs.

This apochromatic correction ensures stars resolve as sharp points against a black background, and high-contrast targets like Jupiter's cloud bands and the lunar terminator are rendered with impressive clarity and true-to-life color. The result is a clean, high-contrast image that holds up even at higher magnifications.

1.25" Eyepiece Compatibility: Tailor Your Magnification

Unlike fixed-magnification binoculars, the BT-120mm ED accepts interchangeable 1.25-inch eyepieces, giving you complete control over your field of view and magnification. This system allows you to adapt the instrument to any target, from wide-field sweeps to high-power planetary observation. The binocular includes a pair of starter eyepieces to get you observing immediately.

• Low Power Viewing: Use long focal length eyepieces to frame large objects like the Andromeda Galaxy (M31) or the North American Nebula (NGC 7000) in their entirety.
• High Power Viewing: Switch to shorter focal length eyepieces to increase magnification for splitting tight double stars like Albireo (Beta Cygni) or resolving globular clusters like the Hercules Cluster (M13).

Mounting the BT-120mm ED: A Requirement for Stability

Due to its considerable size and weight, the BT-120mm ED is designed exclusively for mounted use. A stable platform is not just recommended; it is essential to realizing the optical potential of this instrument. Hand-holding is not a viable option.

These binoculars are optimized for use with a robust fork mount, such as the Explore Scientific U-Mount with tripod, which provides the necessary stability and allows for smooth, intuitive pointing across the sky. Please note that a mount and tripod are not included with the binoculars and must be purchased separately.

BT-120mm ED vs. a Single 120mm Refractor: The Two-Eyed Advantage

While a single 120mm apochromatic refractor offers excellent views, the binocular configuration of the BT-120mm ED provides a distinctly different and often more engaging observing experience.

• Single Telescope Advantage: A traditional 120mm refractor is typically lighter, requires a less specialized mount, and is more easily adapted for astrophotography.
• BT-120mm ED Advantage: Observing with both eyes significantly reduces eye strain and fatigue during long sessions. More importantly, the brain's ability to process information from two eyes enhances perceived contrast and detail, often making faint objects appear more distinct and giving a subtle 3D-like quality to star clusters and nebulae.