{"product_id":"explore-scientific-es-foc3-bc100127","title":"Explore Scientific 3-inch Self-Centering Focuser with Back Cell Adapter for FCD100-127-CF","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e3-inch Self-Centering Focuser Design\u003c\/li\u003e\n\u003cli\u003e17 lb Lifting Capacity for Heavy Imaging Trains\u003c\/li\u003e\n\u003cli\u003e9:1 Dual-Speed Helical Rack-and-Pinion Mechanism\u003c\/li\u003e\n\u003cli\u003e84.5mm of Precise Drawtube Travel\u003c\/li\u003e\n\u003cli\u003eCustom-Fitted Adapter for FCD100-127-CF Telescopes\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c!-- more --\u003e\n\u003cul class=\"tabs\"\u003e\n\u003cli class=\"active\"\u003eDescription\u003c\/li\u003e\n\u003cli\u003eFAQ\u003c\/li\u003e\n\u003cli\u003eSpecifications\u003c\/li\u003e\n\u003cli\u003eIn the Box\u003c\/li\u003e\n\u003cli\u003eWarranty\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cul class=\"tabs-content\"\u003e\n\u003cli class=\"active\"\u003e\n\u003cdiv\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section-center\"\u003e\n\u003ch2\u003e3-inch Self-Centering Focuser with Back Cell Adapter for FCD100-127-CF\u003c\/h2\u003e\n\u003cp\u003eThis Explore Scientific 3-inch Self-Centering Focuser is engineered specifically for the FCD100-127-CF carbon-fiber optical tube, providing an imaging-grade focusing platform with a robust 17 lb lifting capacity. Its 9:1 dual-speed helical rack-and-pinion drive ensures zero slippage with heavy loads, while the self-centering compression system guarantees zero image shift or tilt. With 84.5mm of drawtube travel and 14 internal baffles for maximum contrast, this focuser is a critical upgrade for serious astrophotography.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003e17 lb Capacity with a 9:1 Rack-and-Pinion Drive\u003c\/h3\u003e\n\u003cp\u003eDesigned for heavy imaging trains, this focuser’s helical rack-and-pinion mechanism supports a 17 lb payload without slipping or flexing. Unlike friction-based Crayford focusers that can struggle under the weight of large cameras, filter wheels, and off-axis guiders, the geared design provides a positive, repeatable engagement. The 9:1 fine-focus ratio, facilitated by stainless steel ball bearings, allows for critical focus adjustments essential for high-resolution imaging.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eZero-Tilt Imaging: A Self-Centering System with 14 Baffles\u003c\/h3\u003e\n\u003cp\u003eThe core of this focuser's optical precision is its self-centering compression system, which eliminates tilt and image shift as you lock down your camera. This mechanism ensures your sensor remains perfectly orthogonal to the light path, a non-negotiable requirement for achieving flat fields from corner to corner. To further enhance image quality, the drawtube contains 14 internal baffles that trap stray light, increasing contrast by preventing off-axis reflections from reaching the sensor.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eFCD100-127-CF Integration: Custom Adapter and 84.5mm Travel\u003c\/h3\u003e\n\u003cp\u003eThis focuser includes a pre-installed back cell adapter threaded specifically for the Explore Scientific FCD100-127-CF carbon-fiber refractor, ensuring a secure, rigid connection to the optical tube. An ample 84.5mm of drawtube travel provides the range needed to achieve focus with a wide variety of accessories, from reducers to Barlows. The drawtube terminates in a female M82x1.25 thread, allowing for direct, secure attachment of 2-inch and 3-inch field flatteners and other threaded accessories.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat is the advantage of this FCD100-127-CF focuser's rack-and-pinion design?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe primary advantage is its \u003cstrong\u003e17 lb lifting capacity\u003c\/strong\u003e and resistance to slippage. Unlike Crayford focusers that rely on friction, a rack-and-pinion uses gears for a positive mechanical connection, preventing the drawtube from moving under the weight of a heavy camera and filter wheel.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWill this focuser fit a telescope other than the Explore Scientific FCD100-127-CF?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eNo, this specific model is sold with a back cell adapter threaded exclusively for the Explore Scientific FCD100-127-CF carbon-fiber optical tube. While the base focuser design is used on other scopes, this package is a dedicated upgrade for that model.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow does the self-centering system prevent optical tilt in the FCD100-127-CF focuser?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe self-centering mechanism uses a compression ring that applies uniform pressure around the eyepiece or camera nosepiece. This ensures the accessory is held perfectly on the central optical axis, preventing the tilt and image shift that can be introduced by traditional thumbscrew-based clamps.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan the 17 lb capacity of this focuser handle a full-frame monochrome camera and 7-position filter wheel?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes. A typical heavy imaging train, such as a ZWO ASI6200MM Pro, a 7x2\" filter wheel, and an off-axis guider, weighs between 8 and 12 lbs. The \u003cstrong\u003e17 lb capacity\u003c\/strong\u003e of this focuser provides more than enough support to handle such a setup without flexure or slippage, even when the telescope is pointed near the zenith.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWith 84.5mm of travel, can I reach focus on my FCD100-127-CF with a focal reducer?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, the \u003cstrong\u003e84.5mm drawtube travel\u003c\/strong\u003e provides substantial range to accommodate the change in focal point introduced by most common focal reducers or flatteners. This allows you to achieve sharp focus across a wide variety of imaging configurations without needing extra extension tubes.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat accessories can I connect to the M82x1.25 thread on this focuser?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe female \u003cstrong\u003eM82x1.25 thread\u003c\/strong\u003e is a robust connection standard for larger imaging accessories. It allows you to securely thread on compatible 3-inch field flatteners, reducers, or adapters for direct connection to 2-inch accessories, providing a much more rigid connection than a simple compression fitting.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocuser Type\u003c\/td\u003e\n\u003ctd\u003e3-inch Helical Rack-and-Pinion\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDrive Ratio\u003c\/td\u003e\n\u003ctd\u003e9:1 Dual-Speed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eLifting Capacity\u003c\/td\u003e\n\u003ctd\u003e17 lb\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDrawtube Travel\u003c\/td\u003e\n\u003ctd\u003e84.5mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eClamping Mechanism\u003c\/td\u003e\n\u003ctd\u003eSelf-Centering Compression System\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptical Path Integrity\u003c\/td\u003e\n\u003ctd\u003eZero Tilt, Zero Image Shift\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eInternal Baffling\u003c\/td\u003e\n\u003ctd\u003e14 Baffles\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAccessory Thread\u003c\/td\u003e\n\u003ctd\u003eM82x1.25\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBearings\u003c\/td\u003e\n\u003ctd\u003eStainless Steel Ball Bearings\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCompatibility\u003c\/td\u003e\n\u003ctd\u003eExplore Scientific FCD100-127-CF Carbon Fiber OTA\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003e3-inch Self-Centering Focuser with Back Cell Adapter\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n\u003ca href=\"https:\/\/davidastro.com\/pages\/explore-scientific-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eExplore Scientific Warranty\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Explore Scientific","offers":[{"title":"Default Title","offer_id":52909309886749,"sku":"ES-FOC3-BC100127","price":1400.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/ExploreScientific-3-inch-Self-Centering-Focuser-with-Back-Cell-Adapter-for-FCD100-127-CF-1_06405165-f89f-49ff-91b2-555a3281382b.jpg?v=1789061181","url":"https:\/\/davidastro.com\/products\/explore-scientific-es-foc3-bc100127","provider":"David Astro","version":"1.0","type":"link"}