{"product_id":"bt-70-sf-large-binoculars-with-62-degree-ler-eyepieces","title":"BT-70 SF Large Binoculars with 62 Degree LER Eyepieces","description":"\u003ch1\u003eBT-70 SF Large Binoculars with 62 Degree LER Eyepieces\u003c\/h1\u003e\n\n\u003chr\u003e\n\n\u003ch2\u003eDescription\u003c\/h2\u003e\n\u003cp\u003e\n  The Explore Scientific BT-70 SF is a premium giant binocular built for serious astronomy enthusiasts and dedicated terrestrial observers who demand the best in optical performance. With 70mm objective lenses and a 400mm focal length, this binocular delivers bright, high-contrast views of the moon, planets, deep-sky objects, distant wildlife, and sweeping landscapes. Each eye benefits from its own complete optical system, creating an immersive, three-dimensional viewing experience that dramatically reduces eye fatigue during long observing sessions.\n\u003c\/p\u003e\n\u003cp\u003e\n  The BT-70 ships with two 62-degree 20mm LER (Long Eye Relief) eyepieces for 20x magnification right out of the box, and its standard 1.25\" eyepiece compatibility lets you dial magnification anywhere from 15x to 50x. A rugged magnesium housing with IPX6 waterproofing and nitrogen purging ensures the optics stay fog-free and protected in demanding outdoor conditions - making this an instrument built to perform season after season.\n\u003c\/p\u003e\n\n\u003chr\u003e\n\n\u003ch2\u003eKey Features\u003c\/h2\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003e70mm Objective Lenses:\u003c\/strong\u003e Large aperture gathers abundant light for bright, detailed views of celestial and terrestrial subjects.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e400mm Focal Length \/ f\/5.7:\u003c\/strong\u003e Delivers a wide, bright image with strong contrast across astronomy and nature observation.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eIncluded 62° 20mm LER Eyepieces:\u003c\/strong\u003e Two premium Long Eye Relief eyepieces provide 20x magnification and a 3.1-degree true field of view for comfortable, immersive viewing.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e1.25\" \/ 31.7mm Interchangeable Eyepiece Compatibility:\u003c\/strong\u003e Swap in any standard 1.25\" eyepiece to adjust magnification from 15x to 50x for deep-sky or high-power planetary work.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eAchromatic Refractor Porro Optical Design:\u003c\/strong\u003e Enhanced Multilayer Deposition (EMD) coatings maximize light transmission and deliver sharp, high-contrast images.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eIPX6 Waterproof \u0026amp; Nitrogen-Purged Magnesium Housing:\u003c\/strong\u003e Fully weatherproof construction prevents internal fogging and withstands rugged outdoor use.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e45-Degree Viewing Angle:\u003c\/strong\u003e Ergonomic angled eyepiece design allows relaxed, fatigue-free observation - especially important during extended astronomy sessions.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eExtendable Dew Caps:\u003c\/strong\u003e Help shield objective lenses from dew and stray light for cleaner views in humid or nighttime conditions.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFine Helical Focus:\u003c\/strong\u003e Smooth, precise focus control for sharp images even at high magnification.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eTripod \u0026amp; U-Mount Compatible:\u003c\/strong\u003e Features an integrated carrying handle and standard mount interface - pair with a sturdy photo tripod or the optional Explore Scientific U-Mount with Field Tripod for a rock-steady platform.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003chr\u003e\n\n\u003ch2\u003eOptions \u0026amp; Which to Choose\u003c\/h2\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003e70mm (BT-70):\u003c\/strong\u003e The most compact and lightweight of the lineup, the 70mm is ideal for observers who want portability without sacrificing serious optical performance. A great entry point into giant binocular astronomy and a versatile choice for both stargazing and daytime terrestrial use.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e82mm:\u003c\/strong\u003e Steps up aperture for noticeably brighter images and better resolution on faint deep-sky objects and fine terrestrial detail. A strong all-around choice for dedicated astronomy enthusiasts who want more light-gathering without a dramatic increase in size or weight.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e100mm:\u003c\/strong\u003e Delivers a significant aperture upgrade suited to observers focused on deep-sky astronomy - galaxies, nebulae, and star clusters come alive with greater detail and contrast. Best for those with a stable, heavy-duty mount who want near-telescope-level views in a binocular format.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e120mm:\u003c\/strong\u003e The most powerful configuration in the BT series, offering maximum light-gathering capability for serious deep-sky and planetary observers. Ideal for astronomers with a permanent or semi-permanent setup who want the ultimate binocular viewing experience.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003chr\u003e\n\n\u003ch2\u003eWhat's Included\u003c\/h2\u003e\n\u003cul\u003e\n  \u003cli\u003eExplore Scientific BT-70 SF Giant Binocular\u003c\/li\u003e\n  \u003cli\u003eTwo 62-degree 20mm LER Eyepieces (1.25\")\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003chr\u003e\n\n\u003ch2\u003eWhy You'll Love It\u003c\/h2\u003e\n\u003cp\u003e\n  The BT-70 SF represents a genuine leap in observing comfort and optical quality for anyone serious about astronomy or high-performance nature observation. Unlike standard binoculars, the BT-70's dual full optical systems and 45-degree viewing angle let you observe for hours without the neck strain or eye fatigue that plagues traditional designs. The all-weather magnesium chassis and IPX6 waterproofing mean you can take it to dark sky sites, mountain overlooks, or coastal wildlife refuges without worry. The flexibility to swap eyepieces across the full 1.25\" standard means your accessory investment grows with your interests. Trusted by astronomy enthusiasts and nature observers who refuse to compromise, the BT-70 SF is an instrument you'll reach for night after night - and one that's built to last for years of demanding use.\n\u003c\/p\u003e\n\n\u003chr\u003e\n\n\u003ch2\u003eProduct Specifications\u003c\/h2\u003e\n\u003cdiv class=\"custom-product-faq\"\u003e\n\u003cdetails\u003e\n\u003csummary\u003e\u003cstrong\u003eView Product Specs\u003c\/strong\u003e\u003c\/summary\u003e\n\u003ctable border=\"1\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eItem Number\u003c\/th\u003e\n\u003ctd\u003e01-14200\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eOptical Design\u003c\/th\u003e\n\u003ctd\u003eAchromatic Refractor Porro\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eObjective Lens Diameter\u003c\/th\u003e\n\u003ctd\u003e70 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eFocal Length\u003c\/th\u003e\n\u003ctd\u003e400 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eFocal Ratio\u003c\/th\u003e\n\u003ctd\u003ef\/5.7\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eApparent Field of View\u003c\/th\u003e\n\u003ctd\u003e62 degrees\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eTrue Field of View\u003c\/th\u003e\n\u003ctd\u003e3.1 degrees\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eMagnification (Included Eyepieces)\u003c\/th\u003e\n\u003ctd\u003e20x\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eMagnification Range (1.25\" Eyepieces)\u003c\/th\u003e\n\u003ctd\u003e15x - 50x\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eExit Pupil (Min)\u003c\/th\u003e\n\u003ctd\u003e3.5 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eEye Relief\u003c\/th\u003e\n\u003ctd\u003e15 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eCoating\u003c\/th\u003e\n\u003ctd\u003eEnhanced Multilayer Deposition (EMD)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eWaterproof\u003c\/th\u003e\n\u003ctd\u003eYes - IPX6\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eHousing Material\u003c\/th\u003e\n\u003ctd\u003eMagnesium\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eTotal Length\u003c\/th\u003e\n\u003ctd\u003e370 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eTotal Width\u003c\/th\u003e\n\u003ctd\u003e213 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eTotal Height\u003c\/th\u003e\n\u003ctd\u003e122 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003cth\u003eNet Weight\u003c\/th\u003e\n\u003ctd\u003e3,400 g\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/details\u003e\n\u003c\/div\u003e\u003ch2\u003eFAQ\u003c\/h2\u003e\n\u003cdiv class=\"custom-product-faq\"\u003e\n\u003cdetails\u003e\n\u003csummary\u003eDo I need a tripod to use the BT-70?\u003c\/summary\u003e\n\u003cp class=\"faq-content\"\u003eA tripod is strongly recommended. At 20x magnification and above, even slight hand movement becomes very noticeable, making handheld use impractical for most observers. The BT-70 features a standard tripod mount interface and integrated carrying handle, and pairs perfectly with a sturdy photo tripod or the optional Explore Scientific U-Mount with Field Tripod for a stable, fully adjustable platform.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eCan I use my existing 1.25\" telescope eyepieces with the BT-70?\u003c\/summary\u003e\n\u003cp class=\"faq-content\"\u003eYes - the BT-70 is fully compatible with all standard 1.25\" (31.7mm) eyepieces, which is the most common eyepiece format in amateur astronomy. This means you can use eyepieces you already own or easily expand your collection to access magnification from 15x all the way up to 50x. Optional color and nebula filters in the same 1.25\" format can also be used to enhance contrast on specific astronomical targets.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eIs the BT-70 suitable for daytime use, or is it just for astronomy?\u003c\/summary\u003e\n\u003cp class=\"faq-content\"\u003eThe BT-70 is an excellent daytime observer as well. Its 70mm aperture, bright optics, and 45-degree viewing angle make it ideal for birdwatching, wildlife observation, scenic overlooks, and sporting events - anywhere you want an immersive, high-magnification view of distant subjects. The IPX6 waterproof rating also makes it well-suited for outdoor use in variable weather conditions.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eWhat is the difference between the BT-70 and the larger BT models (82mm, 100mm, 120mm)?\u003c\/summary\u003e\n\u003cp class=\"faq-content\"\u003eThe primary difference between models is aperture size, which directly affects light-gathering ability, image brightness, and resolution of fine detail. The 70mm is the most portable option and delivers excellent performance for most observers. As aperture increases through the 82mm, 100mm, and 120mm models, images become progressively brighter and more detailed - particularly on faint deep-sky objects like galaxies and nebulae. Larger models also require a more substantial mount to support their increased size and weight.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003eWhat does \"nitrogen-purged\" mean, and why does it matter?\u003c\/summary\u003e\n\u003cp class=\"faq-content\"\u003eNitrogen purging means the interior of the binocular has been filled with dry nitrogen gas and sealed. This eliminates moisture inside the optical tube, which prevents internal fogging when you move between temperature extremes - like bringing the binocular from a warm car into cold night air. Combined with the IPX6 waterproof seal, nitrogen purging ensures the optics stay clear and protected throughout years of outdoor use.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003c\/div\u003e","brand":"Explore Scientific","offers":[{"title":"Default Title","offer_id":55918236434737,"sku":"01-14200","price":1299.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1724\/7681\/files\/04a2baeb77cfddfe85c76fd897a8c898_0114200_m_1.jpg?v=1787663236","url":"https:\/\/omahasportsandgames.com\/products\/bt-70-sf-large-binoculars-with-62-degree-ler-eyepieces","provider":"Omaha Sports \u0026 Games","version":"1.0","type":"link"}