{"product_id":"zwo-ff131-apo-flat-field-131mm-apochromatic-refractor","title":"ZWO FF131 APO Flat-Field 131mm Apochromatic Refractor","description":"\u003cstyle\u003e .zw-page { --black: #000000; --ink: #1D1D1F; --paper: #F5F5F7; --white: #FFFFFF; --mute: #86868B; --line: #D2D2D7; --link: #0066CC; --accent: #C6302B; --radius: 22px; --radius-lg: 28px; font-family: -apple-system, BlinkMacSystemFont, \"SF Pro Display\", \"SF Pro\", \"Helvetica Neue\", Helvetica, Arial, sans-serif; font-weight: 400; color: var(--ink); background: var(--white); line-height: 1.47; letter-spacing: -0.003em; -webkit-font-smoothing: antialiased; -moz-osx-font-smoothing: grayscale; overflow-x: hidden; } .zw-page img { max-width: 100%; height: auto; } .zw-page .zw-section { padding: 120px 22px; } @media (max-width: 640px) { .zw-page .zw-section { padding: 80px 22px; } } .zw-page .zw-on-dark { background: var(--black); color: var(--white); } .zw-page .zw-paper { background: var(--paper); } .zw-page .zw-hero-h2 { font-size: clamp(60px, 9vw, 112px); 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} .zw-page .zw-specs-row { display: grid; grid-template-columns: 38% 1fr; gap: 24px; padding: 18px 0; border-bottom: 1px solid var(--line); align-items: start; } .zw-page .zw-specs-label { color: var(--mute); font-weight: 400; font-size: 17px; line-height: 1.5; } .zw-page .zw-specs-value { color: var(--ink); font-weight: 400; font-size: 17px; line-height: 1.5; overflow-wrap: anywhere; } .zw-page .zw-specs-cat { padding: 36px 0 14px; font-size: 13px; font-weight: 600; text-transform: uppercase; letter-spacing: 0.04em; color: var(--ink); } @media (max-width: 640px) { .zw-page .zw-specs-row { font-size: 15px; padding: 14px 0; } } @media (max-width: 380px) { .zw-page .zw-specs-row { font-size: 13.5px; padding: 10px 0; } } .zw-page .zw-specs-head { text-align: center; max-width: 820px; margin: 0 auto 24px; } .zw-page .zw-highlights { display: grid; grid-template-columns: 1fr 1fr; gap: 20px 48px; max-width: 1000px; margin: 0 auto; } .zw-page .zw-highlight-item { display: flex; gap: 14px; align-items: flex-start; } .zw-page .zw-tick { width: 24px; height: 24px; flex-shrink: 0; color: var(--ink); margin-top: 2px; } @media (max-width: 700px) { .zw-page .zw-highlights { grid-template-columns: 1fr; } } .zw-page .zw-link { color: var(--link); font-size: 17px; display: inline-flex; align-items: center; gap: 4px; padding: 10px 4px; min-height: 44px; text-decoration: none; } .zw-page .zw-link svg { width: 18px; height: 18px; } .zw-page .zw-on-dark .zw-link { color: #2997FF; } .zw-page .zw-closing { text-align: center; } .zw-page .zw-closing h2 { max-width: 820px; margin: 0 auto 56px; } .zw-page .zw-perks { display: grid; grid-template-columns: repeat(4, 1fr); gap: 24px; max-width: 1000px; margin: 0 auto; } .zw-page .zw-perk-t { font-size: 17px; font-weight: 600; color: var(--ink); } .zw-page .zw-perk-s { font-size: 14px; color: var(--mute); margin-top: 4px; } @media (max-width: 1024px) { .zw-page .zw-perks { grid-template-columns: repeat(2, 1fr); } } \u003c\/style\u003e\n\u003cdiv class=\"zw-page\"\u003e\n\u003csection class=\"zw-section zw-on-dark zw-hero\"\u003e\n\u003cdiv class=\"zw-hero-inner\"\u003e\n\u003cdiv class=\"zw-eyebrow\"\u003eZWO Flat-Field APO Series\u003c\/div\u003e\n\u003ch2 class=\"zw-hero-h2\"\u003eFF131 APO. \u003cspan class=\"zw-mute\"\u003eFlat field, built in.\u003c\/span\u003e\n\u003c\/h2\u003e\n\u003cp class=\"zw-lead\"\u003eA 131 mm f\/7.5 four-element apochromatic refractor with a native flat field and a 44 mm full-frame image circle. The flagship of the FF series, with 983 mm of focal length and serious light grasp for deep-sky imaging.\u003c\/p\u003e\n\u003cdiv class=\"zw-hero-ctas\"\u003e\n\u003ca class=\"zw-link\" href=\"#zw-features\"\u003eExplore the design \u003csvg stroke-linejoin=\"round\" stroke-linecap=\"round\" stroke-width=\"2.2\" stroke=\"currentColor\" fill=\"none\" viewbox=\"0 0 24 24\"\u003e\u003cpolyline points=\"9 6 15 12 9 18\"\u003e\u003c\/polyline\u003e\u003c\/svg\u003e \u003c\/a\u003e \u003ca class=\"zw-link\" href=\"#zw-specs\"\u003eView specifications \u003csvg stroke-linejoin=\"round\" stroke-linecap=\"round\" stroke-width=\"2.2\" stroke=\"currentColor\" fill=\"none\" viewbox=\"0 0 24 24\"\u003e\u003cpolyline points=\"9 6 15 12 9 18\"\u003e\u003c\/polyline\u003e\u003c\/svg\u003e \u003c\/a\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/section\u003e\n\u003csection class=\"zw-section zw-paper\"\u003e\n\u003cdiv class=\"zw-stats\"\u003e\n\u003cdiv class=\"zw-stat\"\u003e\n\u003cdiv class=\"zw-stat-num\"\u003e131 mm\u003c\/div\u003e\n\u003cdiv class=\"zw-stat-lbl\"\u003eaperture\u003c\/div\u003e\n\u003cdiv class=\"zw-stat-cap\"\u003efour-element air-spaced APO\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"zw-stat\"\u003e\n\u003cdiv class=\"zw-stat-num\"\u003e983 mm\u003c\/div\u003e\n\u003cdiv class=\"zw-stat-lbl\"\u003efocal length\u003c\/div\u003e\n\u003cdiv class=\"zw-stat-cap\"\u003ef\/7.5\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"zw-stat\"\u003e\n\u003cdiv class=\"zw-stat-num\"\u003e44 mm\u003c\/div\u003e\n\u003cdiv class=\"zw-stat-lbl\"\u003eimage circle\u003c\/div\u003e\n\u003cdiv class=\"zw-stat-cap\"\u003efull-frame coverage\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"zw-stat\"\u003e\n\u003cdiv class=\"zw-stat-num\"\u003e7.9 kg\u003c\/div\u003e\n\u003cdiv class=\"zw-stat-lbl\"\u003eoptical tube\u003c\/div\u003e\n\u003cdiv class=\"zw-stat-cap\"\u003e9.4 kg with rings and dovetail\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/section\u003e\n\u003csection class=\"zw-cinema zw-on-dark\"\u003e\n\u003cdiv class=\"zw-cinema-cap\"\u003e\n\u003cspan class=\"zw-eyebrow\"\u003eZWO FF Series\u003c\/span\u003e\n\u003ch2 class=\"zw-h2 zw-grad\"\u003eDesigned as an astrograph first.\u003c\/h2\u003e\n\u003cp class=\"zw-body\"\u003eEvery FF series telescope is built around a native flat field, so the optics, focuser and rear interfaces all serve one goal: clean stars across the whole sensor.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cimg loading=\"lazy\" alt=\"ZWO FF131 APO flat-field apochromatic refractor banner\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0609\/6673\/1845\/files\/zwo-ff131-apo-flat-field-banner.webp?v=1781069482\" class=\"zw-cinema-img\"\u003e\u003c\/section\u003e\n\u003csection class=\"zw-section zw-pullquote\"\u003e\n\u003cp\u003eAttach your camera, reach focus, start imaging. \u003cspan class=\"zw-mute\"\u003eNo flattener. No spacing maths.\u003c\/span\u003e\u003c\/p\u003e\n\u003c\/section\u003e\n\u003csection id=\"zw-features\" class=\"zw-section zw-on-dark\"\u003e\n\u003cdiv class=\"zw-bento\"\u003e\n\u003cdiv class=\"zw-bento-card zw-span-3\"\u003e\n\u003cdiv class=\"zw-eyebrow\"\u003eOptics\u003c\/div\u003e\n\u003ch3 class=\"zw-bento-h\"\u003eFour elements, fully air-spaced.\u003c\/h3\u003e\n\u003cp class=\"zw-body\"\u003eThe FF131 APO uses a four-element, fully air-spaced apochromatic design in which all four elements work together to form the image. One ED (extra-low dispersion) glass element reduces chromatic aberration for cleaner colour correction and sharper stars.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"zw-bento-card zw-span-3\"\u003e\n\u003cdiv class=\"zw-eyebrow\"\u003eNative flat field\u003c\/div\u003e\n\u003ch3 class=\"zw-bento-h\"\u003eFlat to the edge. No flattener.\u003c\/h3\u003e\n\u003cp class=\"zw-body\"\u003eThe flat imaging field is generated by the optical design itself, so there is no field flattener to buy and no back focus calculations to get right. Once focus is achieved, you are ready to capture.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"zw-bento-card zw-span-3\"\u003e\n\u003cdiv class=\"zw-eyebrow\"\u003eFull-frame support\u003c\/div\u003e\n\u003ch3 class=\"zw-bento-h\"\u003e44 mm image circle.\u003c\/h3\u003e\n\u003cp class=\"zw-body\"\u003eA 44 mm corrected image circle fully covers full-frame sensors, with sharp star fields and consistent illumination from centre to corner. Smaller APS-C and dedicated astronomy sensors have generous headroom.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"zw-bento-card zw-span-3\"\u003e\n\u003cdiv class=\"zw-eyebrow\"\u003eFocusing\u003c\/div\u003e\n\u003ch3 class=\"zw-bento-h\"\u003e1:10 dual-speed control.\u003c\/h3\u003e\n\u003cp class=\"zw-body\"\u003eA rigid 3″ rack-and-pinion focuser offers precise control, and the 1:10 coarse and fine adjustment makes critical focus easy to hit. A built-in 360° rotator at the rear sets your framing without disturbing focus.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"zw-bento-card zw-span-3\"\u003e\n\u003cdiv class=\"zw-eyebrow\"\u003eBuild\u003c\/div\u003e\n\u003ch3 class=\"zw-bento-h\"\u003eRetractable dew shield.\u003c\/h3\u003e\n\u003cp class=\"zw-body\"\u003eThe dew shield retracts to shorten the tube for packing and travel. Precision CNC machining, a high-quality painted finish and an internal anti-reflection coating keep stray light down and image contrast up.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"zw-bento-card zw-span-3\"\u003e\n\u003cdiv class=\"zw-eyebrow\"\u003eConnectivity\u003c\/div\u003e\n\u003ch3 class=\"zw-bento-h\"\u003eAdapters in the box.\u003c\/h3\u003e\n\u003cp class=\"zw-body\"\u003eA four-section photography extension tube with a 2″ filter thread is included, along with rear adapters in M48×0.75 and M54×0.75 standards. The quick-release mounting rings detach in seconds for fast setup and teardown.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/section\u003e\n\u003csection class=\"zw-section\"\u003e\n\u003cdiv class=\"zw-split\"\u003e\n\u003cdiv class=\"zw-split-text\"\u003e\n\u003cdiv class=\"zw-eyebrow\"\u003eQuadruplet optics\u003c\/div\u003e\n\u003ch2 class=\"zw-h2\"\u003eFour elements. \u003cspan class=\"zw-mute\"\u003eOne flat field.\u003c\/span\u003e\n\u003c\/h2\u003e\n\u003cp class=\"zw-body\"\u003eAll four air-spaced elements work together to form the image, with one ED glass element controlling chromatic aberration for clean colour correction and tight, well-defined stars.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cimg loading=\"lazy\" alt=\"ZWO FF131 APO four-element air-spaced apochromatic optical design\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0609\/6673\/1845\/files\/zwo-ff131-apo-four-element-optical-design.webp?v=1781069482\" class=\"zw-split-img\"\u003e\n\u003c\/div\u003e\n\u003c\/section\u003e\n\u003csection class=\"zw-section zw-split-stack\"\u003e\n\u003cdiv class=\"zw-split\"\u003e\n\u003cimg loading=\"lazy\" alt=\"ZWO FF131 APO optical path diagram showing ED glass element position\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0609\/6673\/1845\/files\/zwo-ff131-apo-optical-path-diagram.webp?v=1781069482\" class=\"zw-split-img\"\u003e\n\u003cdiv class=\"zw-split-text\"\u003e\n\u003cdiv class=\"zw-eyebrow\"\u003eOptical layout\u003c\/div\u003e\n\u003ch2 class=\"zw-h2\"\u003eThe light path, \u003cspan class=\"zw-mute\"\u003eend to end.\u003c\/span\u003e\n\u003c\/h2\u003e\n\u003cp class=\"zw-body\"\u003eThe optical layout delivers a corrected, flat field at the sensor with no additional optics in the imaging train. What leaves the objective arrives at your camera, flat.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/section\u003e\n\u003csection class=\"zw-section zw-split-stack\"\u003e\n\u003cdiv class=\"zw-split\"\u003e\n\u003cdiv class=\"zw-split-text\"\u003e\n\u003cdiv class=\"zw-eyebrow\"\u003eFull-frame ready\u003c\/div\u003e\n\u003ch2 class=\"zw-h2\"\u003e44 mm \u003cspan class=\"zw-mute\"\u003eimage circle.\u003c\/span\u003e\n\u003c\/h2\u003e\n\u003cp class=\"zw-body\"\u003eFull-frame sensors are covered corner to corner with sharp star fields and consistent illumination, and smaller sensors sit comfortably inside the sweet spot.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cimg loading=\"lazy\" alt=\"ZWO FF131 APO 44mm image circle with full-frame camera support\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0609\/6673\/1845\/files\/zwo-ff131-apo-44mm-image-circle.webp?v=1781069482\" class=\"zw-split-img\"\u003e\n\u003c\/div\u003e\n\u003c\/section\u003e\n\u003csection class=\"zw-section zw-split-stack\"\u003e\n\u003cdiv class=\"zw-split\"\u003e\n\u003cimg loading=\"lazy\" alt=\"ZWO FF131 APO coarse and fine focus adjustment\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0609\/6673\/1845\/files\/zwo-ff131-apo-focus-adjustment.webp?v=1781069482\" class=\"zw-split-img\"\u003e\n\u003cdiv class=\"zw-split-text\"\u003e\n\u003cdiv class=\"zw-eyebrow\"\u003eCritical focus\u003c\/div\u003e\n\u003ch2 class=\"zw-h2\"\u003eCoarse and fine, \u003cspan class=\"zw-mute\"\u003e1:10.\u003c\/span\u003e\n\u003c\/h2\u003e\n\u003cp class=\"zw-body\"\u003eThe rigid 3″ rack-and-pinion focuser moves heavy imaging trains smoothly, and the 1:10 fine knob gives you the resolution to land exact focus on a star.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/section\u003e\n\u003csection class=\"zw-section zw-split-stack\"\u003e\n\u003cdiv class=\"zw-split\"\u003e\n\u003cdiv class=\"zw-split-text\"\u003e\n\u003cdiv class=\"zw-eyebrow\"\u003eFraming\u003c\/div\u003e\n\u003ch2 class=\"zw-h2\"\u003e360° \u003cspan class=\"zw-mute\"\u003eof rotation.\u003c\/span\u003e\n\u003c\/h2\u003e\n\u003cp class=\"zw-body\"\u003eA built-in rotator at the rear lets you set the camera angle for perfect framing without unthreading anything or disturbing focus.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cimg loading=\"lazy\" alt=\"ZWO FF131 APO built-in 360 degree camera rotator and 1:10 focuser\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0609\/6673\/1845\/files\/zwo-ff131-apo-camera-rotator.webp?v=1781069483\" class=\"zw-split-img\"\u003e\n\u003c\/div\u003e\n\u003c\/section\u003e\n\u003csection class=\"zw-section zw-split-stack\"\u003e\n\u003cdiv class=\"zw-split\"\u003e\n\u003cimg loading=\"lazy\" alt=\"ZWO FF131 APO quick-release mounting rings and retractable dew shield\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0609\/6673\/1845\/files\/zwo-ff131-apo-rings-dew-shield.webp?v=1781069482\" class=\"zw-split-img\"\u003e\n\u003cdiv class=\"zw-split-text\"\u003e\n\u003cdiv class=\"zw-eyebrow\"\u003eField-ready build\u003c\/div\u003e\n\u003ch2 class=\"zw-h2\"\u003eQuick-release rings. \u003cspan class=\"zw-mute\"\u003eRetractable dew shield.\u003c\/span\u003e\n\u003c\/h2\u003e\n\u003cp class=\"zw-body\"\u003eThe mounting rings detach in seconds for fast setup and teardown, and the dew shield slides back to shorten the tube for transport. CNC machining and an internal anti-reflection coating keep contrast high.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/section\u003e\n\u003csection class=\"zw-section zw-split-stack\"\u003e\n\u003cdiv class=\"zw-split\"\u003e\n\u003cdiv class=\"zw-split-text\"\u003e\n\u003cdiv class=\"zw-eyebrow\"\u003eIn the box\u003c\/div\u003e\n\u003ch2 class=\"zw-h2\"\u003ePhotography \u003cspan class=\"zw-mute\"\u003eextension tube.\u003c\/span\u003e\n\u003c\/h2\u003e\n\u003cp class=\"zw-body\"\u003eA four-section photographic extension tube with a 2″ filter thread is included, plus M48×0.75 and M54×0.75 rear adapters, connecting cameras, filters and accessories cleanly out of the box.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cimg loading=\"lazy\" alt=\"ZWO FF131 APO four-section photography extension tube with 2 inch filter thread\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0609\/6673\/1845\/files\/zwo-ff131-apo-extension-tube.webp?v=1781069483\" class=\"zw-split-img\"\u003e\n\u003c\/div\u003e\n\u003c\/section\u003e\n\u003csection class=\"zw-section zw-split-stack\"\u003e\n\u003cdiv class=\"zw-split\"\u003e\n\u003cimg loading=\"lazy\" alt=\"ZWO FF131 APO 131mm flat-field apochromatic refractor showing objective lens\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0609\/6673\/1845\/files\/zwo-ff131-apo-refractor-front-objective-desc.webp?v=1781069482\" class=\"zw-split-img\"\u003e\n\u003cdiv class=\"zw-split-text\"\u003e\n\u003cdiv class=\"zw-eyebrow\"\u003eAperture and reach\u003c\/div\u003e\n\u003ch2 class=\"zw-h2\"\u003e131 mm of light grasp, \u003cspan class=\"zw-mute\"\u003e983 mm of reach.\u003c\/span\u003e\n\u003c\/h2\u003e\n\u003cp class=\"zw-body\"\u003eThe flagship of the FF series pulls in the most light and resolves the finest detail of the range, and the 983 mm focal length frames smaller targets tightly. The optical tube weighs 7.9 kg, or 9.4 kg with the handle, mounting rings and dovetail plate fitted.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/section\u003e\n\u003csection class=\"zw-cinema zw-on-dark\"\u003e\n\u003cdiv class=\"zw-cinema-cap\"\u003e\n\u003cspan class=\"zw-eyebrow\"\u003eFlexible connectivity\u003c\/span\u003e\n\u003ch2 class=\"zw-h2 zw-grad\"\u003eOne telescope. Three configurations.\u003c\/h2\u003e\n\u003cp class=\"zw-body\"\u003ePair the FF131 APO with ZWO ASI astronomy cameras, attach a DSLR or mirrorless body, or drop in a diagonal and eyepiece for visual observing. Focus is reached within a back focus range of 42–73 mm, measured from the M54–M48 interface shoulder. Visual accessories are available separately.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cimg loading=\"lazy\" alt=\"ZWO FF131 APO configurations for astrophotography cameras, DSLR and mirrorless cameras, and visual observation\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0609\/6673\/1845\/files\/zwo-ff131-apo-connectivity-configurations.webp?v=1781069483\" class=\"zw-cinema-img\"\u003e\u003c\/section\u003e\n\u003csection id=\"zw-highlights\" class=\"zw-section\"\u003e\n\u003cdiv class=\"zw-specs-head\"\u003e\n\u003ch2 class=\"zw-h2\"\u003eEvery detail, \u003cspan class=\"zw-mute\"\u003econsidered.\u003c\/span\u003e\n\u003c\/h2\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"zw-highlights\"\u003e\n\u003cdiv class=\"zw-highlight-item\"\u003e\n\u003csvg stroke-linejoin=\"round\" stroke-linecap=\"round\" stroke-width=\"2.4\" stroke=\"currentColor\" fill=\"none\" viewbox=\"0 0 24 24\" class=\"zw-tick\"\u003e\u003cpolyline points=\"20 6 9 17 4 12\"\u003e\u003c\/polyline\u003e\u003c\/svg\u003e\n\u003cp class=\"zw-body\"\u003eFour-element, fully air-spaced apochromatic design with one ED glass element.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"zw-highlight-item\"\u003e\n\u003csvg stroke-linejoin=\"round\" stroke-linecap=\"round\" stroke-width=\"2.4\" stroke=\"currentColor\" fill=\"none\" viewbox=\"0 0 24 24\" class=\"zw-tick\"\u003e\u003cpolyline points=\"20 6 9 17 4 12\"\u003e\u003c\/polyline\u003e\u003c\/svg\u003e\n\u003cp class=\"zw-body\"\u003eNative flat-field design, no separate field flattener or spacing adjustments required.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"zw-highlight-item\"\u003e\n\u003csvg stroke-linejoin=\"round\" stroke-linecap=\"round\" stroke-width=\"2.4\" stroke=\"currentColor\" fill=\"none\" viewbox=\"0 0 24 24\" class=\"zw-tick\"\u003e\u003cpolyline points=\"20 6 9 17 4 12\"\u003e\u003c\/polyline\u003e\u003c\/svg\u003e\n\u003cp class=\"zw-body\"\u003e44 mm image circle with full-frame sensor support and edge-to-edge sharpness.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"zw-highlight-item\"\u003e\n\u003csvg stroke-linejoin=\"round\" stroke-linecap=\"round\" stroke-width=\"2.4\" stroke=\"currentColor\" fill=\"none\" viewbox=\"0 0 24 24\" class=\"zw-tick\"\u003e\u003cpolyline points=\"20 6 9 17 4 12\"\u003e\u003c\/polyline\u003e\u003c\/svg\u003e\n\u003cp class=\"zw-body\"\u003e3″ rack-and-pinion focuser with 1:10 coarse and fine adjustment.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"zw-highlight-item\"\u003e\n\u003csvg stroke-linejoin=\"round\" stroke-linecap=\"round\" stroke-width=\"2.4\" stroke=\"currentColor\" fill=\"none\" viewbox=\"0 0 24 24\" class=\"zw-tick\"\u003e\u003cpolyline points=\"20 6 9 17 4 12\"\u003e\u003c\/polyline\u003e\u003c\/svg\u003e\n\u003cp class=\"zw-body\"\u003eBuilt-in 360° rotator for precise camera angle adjustment.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"zw-highlight-item\"\u003e\n\u003csvg stroke-linejoin=\"round\" stroke-linecap=\"round\" stroke-width=\"2.4\" stroke=\"currentColor\" fill=\"none\" viewbox=\"0 0 24 24\" class=\"zw-tick\"\u003e\u003cpolyline points=\"20 6 9 17 4 12\"\u003e\u003c\/polyline\u003e\u003c\/svg\u003e\n\u003cp class=\"zw-body\"\u003eRetractable dew shield with internal anti-reflection coating for higher contrast.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"zw-highlight-item\"\u003e\n\u003csvg stroke-linejoin=\"round\" stroke-linecap=\"round\" stroke-width=\"2.4\" stroke=\"currentColor\" fill=\"none\" viewbox=\"0 0 24 24\" class=\"zw-tick\"\u003e\u003cpolyline points=\"20 6 9 17 4 12\"\u003e\u003c\/polyline\u003e\u003c\/svg\u003e\n\u003cp class=\"zw-body\"\u003eQuick-release mounting rings for fast setup and teardown.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"zw-highlight-item\"\u003e\n\u003csvg stroke-linejoin=\"round\" stroke-linecap=\"round\" stroke-width=\"2.4\" stroke=\"currentColor\" fill=\"none\" viewbox=\"0 0 24 24\" class=\"zw-tick\"\u003e\u003cpolyline points=\"20 6 9 17 4 12\"\u003e\u003c\/polyline\u003e\u003c\/svg\u003e\n\u003cp class=\"zw-body\"\u003eFour-section photography extension tube with 2″ filter thread plus M48×0.75 and M54×0.75 rear adapters included.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/section\u003e\n\u003csection id=\"zw-specs\" class=\"zw-section zw-paper\"\u003e\n\u003cdiv class=\"zw-specs-head\"\u003e\n\u003ch2 class=\"zw-h2\"\u003eSpecifications.\u003c\/h2\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"zw-specs\"\u003e\n\u003cdiv class=\"zw-specs-cat\"\u003eOptics\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-row\"\u003e\n\u003cdiv class=\"zw-specs-label\"\u003eEffective aperture\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-value\"\u003e131 mm\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-row\"\u003e\n\u003cdiv class=\"zw-specs-label\"\u003eFocal length\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-value\"\u003e983 mm\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-row\"\u003e\n\u003cdiv class=\"zw-specs-label\"\u003eFocal ratio\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-value\"\u003ef\/7.5\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-row\"\u003e\n\u003cdiv class=\"zw-specs-label\"\u003eObjective type\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-value\"\u003eFour-element air-spaced APO (including one ED element)\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-row\"\u003e\n\u003cdiv class=\"zw-specs-label\"\u003eImage circle\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-value\"\u003e44 mm\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-row\"\u003e\n\u003cdiv class=\"zw-specs-label\"\u003eIntegrated field flattener design\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-value\"\u003eYes\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-cat\"\u003eFocuser and rotation\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-row\"\u003e\n\u003cdiv class=\"zw-specs-label\"\u003eFocuser\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-value\"\u003e3″ rack-and-pinion, 1:10 coarse and fine adjustment\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-row\"\u003e\n\u003cdiv class=\"zw-specs-label\"\u003eCamera rotator\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-value\"\u003eBuilt-in, 360°\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-cat\"\u003eBack focus\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-row\"\u003e\n\u003cdiv class=\"zw-specs-label\"\u003eBack focus range\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-value\"\u003e42–73 mm, measured from the M54–M48 interface shoulder\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-cat\"\u003eMaximum rear connection length (focuser retracted)\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-row\"\u003e\n\u003cdiv class=\"zw-specs-label\"\u003eImaging mode\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-value\"\u003e73 mm (from the M48×0.75 male thread)\u003cbr\u003e91 mm (from the M54×0.75 male thread)\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-row\"\u003e\n\u003cdiv class=\"zw-specs-label\"\u003eObservation mode\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-value\"\u003e131 mm (from the 1.25″ interface)\u003cbr\u003e142 mm (from the 2″ interface)\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-cat\"\u003eMinimum rear connection length (focuser retracted)\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-row\"\u003e\n\u003cdiv class=\"zw-specs-label\"\u003eImaging mode\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-value\"\u003e42 mm (from M48×0.75 male thread)\u003cbr\u003e60 mm (from M54×0.75 male thread)\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-row\"\u003e\n\u003cdiv class=\"zw-specs-label\"\u003eObservation mode\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-value\"\u003e100 mm (from 1.25″ interface)\u003cbr\u003e111 mm (from 2″ interface)\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-cat\"\u003eDimensions and weight\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-row\"\u003e\n\u003cdiv class=\"zw-specs-label\"\u003eOverall length\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-value\"\u003e878 mm (1.25″ interface retracted)\u003cbr\u003e941 mm (photography extension tube retracted)\u003cbr\u003e963 mm (1.25″ interface, dew shield extended)\u003cbr\u003e1026 mm (photography extension tube, dew shield extended)\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-row\"\u003e\n\u003cdiv class=\"zw-specs-label\"\u003eTelescope body weight\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-value\"\u003e7.9 kg\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-row\"\u003e\n\u003cdiv class=\"zw-specs-label\"\u003eStandard configuration weight\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-value\"\u003e9.4 kg (including handle, mounting rings and dovetail plate)\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-cat\"\u003eInterfaces\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-row\"\u003e\n\u003cdiv class=\"zw-specs-label\"\u003eRear interfaces\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-value\"\u003eM78×1 – 55 mm extension adapter\u003cbr\u003eM78×1 – M54×0.75\u003cbr\u003eM54×0.75 – M54×0.75\u003cbr\u003eM54×0.75 – M48×0.75 (built-in M48×0.75 filter thread)\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-cat\"\u003eIn the box\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-row\"\u003e\n\u003cdiv class=\"zw-specs-label\"\u003eFF131 APO optical tube\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-value\"\u003eWith handle, mounting rings and dovetail plate\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-row\"\u003e\n\u003cdiv class=\"zw-specs-label\"\u003ePhotography extension tube\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-value\"\u003eFour-section, with 2″ filter thread, M48×0.75 and M54×0.75 rear adapters\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-row\"\u003e\n\u003cdiv class=\"zw-specs-label\"\u003eDocumentation\u003c\/div\u003e\n\u003cdiv class=\"zw-specs-value\"\u003eUser manual, inspection sheet, warranty card\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/section\u003e\n\u003csection class=\"zw-section zw-paper zw-closing\"\u003e\n\u003ch2 class=\"zw-h2\"\u003eBuilt to last a lifetime.\u003c\/h2\u003e\n\u003cdiv class=\"zw-perks\"\u003e\n\u003cdiv class=\"zw-perk\"\u003e\n\u003cdiv class=\"zw-perk-t\"\u003eAustralian warranty\u003c\/div\u003e\n\u003cdiv class=\"zw-perk-s\"\u003eFull local cover\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"zw-perk\"\u003e\n\u003cdiv class=\"zw-perk-t\"\u003eShips from Sydney\u003c\/div\u003e\n\u003cdiv class=\"zw-perk-s\"\u003eFrom local stock\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"zw-perk\"\u003e\n\u003cdiv class=\"zw-perk-t\"\u003eExpert advice\u003c\/div\u003e\n\u003cdiv class=\"zw-perk-s\"\u003eFrom working astronomers\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"zw-perk\"\u003e\n\u003cdiv class=\"zw-perk-t\"\u003e40+ years\u003c\/div\u003e\n\u003cdiv class=\"zw-perk-s\"\u003eIn Australian astronomy\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/section\u003e\n\u003c\/div\u003e","brand":"ZWO","offers":[{"title":"Default Title","offer_id":45120715653189,"sku":"ZWO FF131-APO","price":3349.0,"currency_code":"AUD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0609\/6673\/1845\/files\/zwo-ff131-apo-refractor-side.webp?v=1781069404","url":"https:\/\/bintel.com.au\/zh\/products\/zwo-ff131-apo-flat-field-131mm-apochromatic-refractor","provider":"The Binocular and Telescope Shop","version":"1.0","type":"link"}