{"product_id":"explore-scientific-es-foc3","title":"Explore Scientific 3-inch Self-Centering Focuser","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e3-inch self-centering draw tube\u003c\/li\u003e\n\u003cli\u003e17 lb (7.7 kg) lifting capacity\u003c\/li\u003e\n\u003cli\u003e9:1 dual-speed focusing system\u003c\/li\u003e\n\u003cli\u003e84.5mm of precision draw tube travel\u003c\/li\u003e\n\u003cli\u003eRotatable back cell adapter with no-tool knobs\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\u003eExplore Scientific 3-inch Self-Centering Focuser\u003c\/h2\u003e\n\u003cp\u003eThe Explore Scientific 3-inch Self-Centering Focuser is engineered to carry a heavy 17-pound imaging payload without introducing flexure, tilt, or image shift. Its robust black anodized aluminum body weighs 5.7 pounds and houses a helical rack-and-pinion system with 84.5mm of travel. A 9:1 dual-speed mechanism provides the precise control necessary for critical astrophotography, ensuring your entire optical train remains rigid and perfectly aligned.\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\u003eSelf-Centering Design: A 17 lb Capacity with Zero Image Shift\u003c\/h3\u003e\n\u003cp\u003eThis focuser's core strength is its self-centering compression system, which applies uniform pressure around the draw tube to guarantee a secure, perfectly centered fit for your accessories. This design eliminates the instability that can ruin long exposures, providing a stable base for an imaging setup weighing up to 17 pounds. The interior of the 3-inch draw tube is lined with multiple baffles to absorb stray light and maximize image contrast.\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\u003ePrecision Control: A 9:1 Dual-Speed Helical System\u003c\/h3\u003e\n\u003cp\u003eAchieving critical focus is managed by a 9:1 dual-speed system built with a stainless-steel focus shaft and ball bearings for smooth, repeatable adjustments. The draw tube is moved by a helical rack-and-pinion gear system lubricated with marine-grade PTFE silicone, minimizing backlash for maximum precision. This system is also compatible with popular aftermarket electronic focuser devices for automated control.\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\u003eRotatable Mounting for 120mm-140mm ES Refractors\u003c\/h3\u003e\n\u003cp\u003eThe focuser attaches to select Explore Scientific refractors (from 120mm to 140mm aperture) via a dedicated back cell adapter. This adapter features large, no-tool knobs that allow you to rotate the entire focuser assembly by hand, making it easy to frame your target without interrupting an imaging session. For connecting accessories, the draw tube accepts 2-inch or 3-inch hardware with a secure twist-lock and includes M82 x 1.25 pitch threads for attaching correctors and other adapters.\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\u003eCritical Installation Notes for Specific Telescope Models\u003c\/h3\u003e\n\u003cp\u003eProper installation of this focuser depends on your specific Explore Scientific telescope model. Please review these requirements carefully before purchase to ensure compatibility and determine the necessary installation path.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eWhite-Tube Telescopes:\u003c\/strong\u003e Models with threaded back cells must be shipped to Explore Scientific for professional installation of the back cell adapter. This service will be arranged by customer service after purchase.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFPL53-165CF Telescopes:\u003c\/strong\u003e These models require the purchase of a new, separate back cell adapter for the focuser to be installed.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTED15208CF Telescope:\u003c\/strong\u003e This model does not require a back cell adapter. The 3-inch Self-Centering Focuser fits directly into the telescope's existing back cell.\u003c\/li\u003e\n\u003c\/ul\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 primary advantage of the 3-inch Self-Centering Focuser?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe main advantage is its ability to hold a heavy imaging train, up to \u003cstrong\u003e17 pounds\u003c\/strong\u003e, without flexure or tilt. The self-centering compression mechanism ensures all components are perfectly aligned with the optical axis, which is critical for sharp, round stars across the entire image field.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWill the Explore Scientific 3-inch Focuser fit my ED127 refractor?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, this focuser is designed for Explore Scientific refractors with apertures from 120mm to 140mm, which includes the ED127. If you have a white-tube model with a threaded back cell, the telescope must be sent to Explore Scientific for installation.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow does the focuser's rotation system work for framing targets?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe focuser attaches via a back cell adapter that has large, hand-turnable knobs. Loosening these knobs allows the entire focuser body to rotate smoothly, letting you perfectly frame an object like the Andromeda Galaxy (M31) without changing focus or disassembling your camera setup.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan I attach a field flattener or reducer to the 3-inch Self-Centering Focuser?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes. The draw tube features an \u003cstrong\u003eM82 x 1.25 pitch thread\u003c\/strong\u003e that accepts a variety of threaded adapters, field flatteners, and focal reducers. It also includes a standard twist-lock compression fitting for 2-inch and 3-inch accessories.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIs the 5.7 lb weight of this focuser a concern for my mount?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe \u003cstrong\u003e5.7 lb\u003c\/strong\u003e weight is a result of its heavy-duty construction needed to support a 17 lb payload. While robust, this weight must be factored into your total payload calculation. Ensure your equatorial mount can handle the combined weight of your telescope, this focuser, and your full imaging train to maintain tracking accuracy.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan I automate focusing with the 3-inch Self-Centering Focuser?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, the focusing system is designed to be compatible with popular aftermarket electronic and automated focusing devices. This allows for remote and precise focus adjustments during an imaging session.\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\u003eHelical Rack-and-Pinion\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDraw Tube Diameter\u003c\/td\u003e\n\u003ctd\u003e3 inches\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eLifting Capacity\u003c\/td\u003e\n\u003ctd\u003e17 lbs (7.7 kg)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocus System\u003c\/td\u003e\n\u003ctd\u003e9:1 Dual-Speed\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDraw Tube Travel\u003c\/td\u003e\n\u003ctd\u003e84.5mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eWeight\u003c\/td\u003e\n\u003ctd\u003e5.7 lbs (2.6 kg)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMaterial\u003c\/td\u003e\n\u003ctd\u003eBlack Anodized Aluminum\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAccessory Compatibility\u003c\/td\u003e\n\u003ctd\u003e2-inch and 3-inch (Twist-Lock)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAdapter Thread\u003c\/td\u003e\n\u003ctd\u003eM82 x 1.25 Pitch\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eGTIN\u003c\/td\u003e\n\u003ctd\u003e811803035683\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\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":52909321486621,"sku":"ES-FOC3","price":849.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/ExploreScientific-3-inch-Self-Centering-Focuser-1_d3793e14-9aa0-4b90-9be2-69d0e3a17387.jpg?v=1789061234","url":"https:\/\/davidastro.com\/en-us\/products\/explore-scientific-es-foc3","provider":"David Astro","version":"1.0","type":"link"}