{"product_id":"william-optics-gran-turismo-81-iv-triplet-apo-f-5-9-used-f81gtivrd-u","title":"William Optics Gran Turismo 81 IV Triplet APO f\/5.9 + Reducer - USED (F81GTIVRD-U)","description":"\u003ch1\u003eWilliam Optics Gran Turismo 81 IV Triplet APO f\/5.9 - USED\u003c\/h1\u003e\n\u003ch2\u003e\u003cspan style=\"color: #fc0404;\"\u003e\u003cstrong\u003eThis telescope is in really good condition. Please note that no Dovetail is included. Comes with a diagonal and Flattener, in excellent condition.\u003c\/strong\u003e\u003c\/span\u003e\u003c\/h2\u003e\n\u003cp\u003eThe William Optics Gran Turismo 81 IV Triplet APO f\/5.9 has been designed to deliver excellent color correction and sharpness due to its triplet APO optics. It features an 81 mm aperture, 472 mm focal length, and f\/5.9 F-ratio for enhanced clarity and brightness. This optical system is capable of capturing stunning widefield images that are free from chromatic aberrations.\u003c\/p\u003e\n\u003ch2\u003eWilliam Optics 0.8x Flattener\/Reducer - USED\u003c\/h2\u003e\n\u003cdiv class=\"rte product-single__description\"\u003e\n\u003cdiv class=\"description ui-tabs ui-widget ui-widget-content ui-corner-all\"\u003e\n\u003cdiv class=\"ui-tabs-panel ui-widget-content ui-corner-bottom\"\u003eThis William Optics 0.8x Flattener\/Reducer has been designed to optimize the flat-field imaging performance of William Optics GT71, GT81, Z81 \u0026amp; Z103 refactors. The APO triplet optics of the Field Flattener and Reducer was made with Ohara glass and fully multi-coated to provide good illumination and a beautifully flat field across 97% of full frame sensors.\u003c\/div\u003e\n\u003cdiv class=\"ui-tabs-panel ui-widget-content ui-corner-bottom\"\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003cdiv class=\"ui-tabs-panel ui-widget-content ui-corner-bottom\"\u003eThe reducing factor is 0.8X. Designed with M63 threads on the telescope side, the Field Flattener and Reducer will thread directly into the telescope. Just remove the three screws on the focuser adapter, take off the adapter, and thread the focal reducer\/field flattener on in it's stead. The Field Flattener and Reducer has 2\" threads on the opposite side to accept a 48mm (Wide) T ring for your DSLR. There is even a slot behind the 2\" threads to accept an M48 filter.\u003c\/div\u003e\n\u003cdiv class=\"ui-tabs-panel ui-widget-content ui-corner-bottom\"\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003cdiv class=\"ui-tabs-panel ui-widget-content ui-corner-bottom\"\u003e\n\u003cdiv class=\"rte product-single__description\"\u003e\n\u003cdiv class=\"description ui-tabs ui-widget ui-widget-content ui-corner-all\"\u003e\n\u003cdiv class=\"ui-tabs-panel ui-widget-content ui-corner-bottom\"\u003eThe Field Flattener and Reducer is adjustable to help you achieve the proper back focus. Adjustment distances \u0026amp; back focus, as well as the image circle measurement for each of the telescopes are listed below.\u003c\/div\u003e\n\u003cdiv class=\"ui-tabs-panel ui-widget-content ui-corner-bottom\"\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003cdiv class=\"ui-tabs-panel ui-widget-content ui-corner-bottom\"\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003cdiv class=\"ui-tabs-panel ui-widget-content ui-corner-bottom\"\u003e\n\u003cstrong\u003e\u003c\/strong\u003e\u003cbr\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"ui-tabs-panel ui-widget-content ui-corner-bottom\"\u003e\n\u003cstrong\u003eFull frame size\u003c\/strong\u003e\n\u003cul\u003e\n\u003cli\u003eDesigned with nearly Full frame chip-size DSLR cameras in mind.\u003c\/li\u003e\n\u003cli\u003eFMC tripllet APO design.\u003c\/li\u003e\n\u003cli\u003eProduced entirely with the best Ohara optical glasses.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cstrong\u003eAmazing\u003c\/strong\u003e\n\u003cul\u003e\n\u003cli\u003eReducing factor 0.8X.\u003c\/li\u003e\n\u003cli\u003eAdjustable design, for perfect back focus it can be used with other models of refractor\u003c\/li\u003e\n\u003cli\u003e48mm filter ready.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cstrong\u003eEasy to Use\u003c\/strong\u003e\n\u003cul\u003e\n\u003cli\u003eWill accept any standard 48mm wide T-ring for your camera. Not compatible with smaller 42mm T rings.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cstrong\u003eSuitable for\u003c\/strong\u003e\n\u003cul\u003e\n\u003cli\u003eNewer GT71, GT81, Z81, Z103 scopes that have a female M63 thread. Therefore, check your telescope before ordering.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cstrong\u003eAmount of adjustment:\u003c\/strong\u003e\n\u003cul\u003e\n\u003cli\u003eGT71 - 9.1 mm\u003c\/li\u003e\n\u003cli\u003eGT81 - 7.1 mm\u003c\/li\u003e\n\u003cli\u003eZ103 - 2.5 mm\u003c\/li\u003e\n\u003cli\u003eZ81 - 5.2 mm\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cstrong\u003eBack focus:\u003c\/strong\u003e\n\u003cul\u003e\n\u003cli\u003eGT71 - 64.1 mm\u003c\/li\u003e\n\u003cli\u003eGT81 - 62.1 mm\u003c\/li\u003e\n\u003cli\u003eZ103 - 57.5 mm\u003c\/li\u003e\n\u003cli\u003eZ81 - 60.2 mm\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cstrong\u003eImage Circle:\u003c\/strong\u003e\n\u003cul\u003e\n\u003cli\u003eGT71 - 44.4 mm\u003c\/li\u003e\n\u003cli\u003eGT81 - 44.4 mm\u003c\/li\u003e\n\u003cli\u003eZ103 - 43.1 mm\u003c\/li\u003e\n\u003cli\u003eZ81 - 44.3 mm\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch4\u003ePhotos Taken with the Telescope :\u003c\/h4\u003e\n\u003cp\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0652\/6245\/2965\/files\/M33_TriangulumGalaxy_-2024-09-04-25x300s_2.1h--10CGT81IVASI2600MCLExtr-Astrowizard.jpg?v=1792678944\" alt=\"\"\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0652\/6245\/2965\/files\/M31_AndromedaGalaxy_-2024-09-04-29x300s_2.4h--10C-GT81IVASI2600MC-Astrowizard.jpg?v=1792678941\" alt=\"\"\u003e\u003c\/p\u003e\n\u003cp\u003e \u003c\/p\u003e\n\u003cp\u003e\u003cimg height=\"641\" width=\"641\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0652\/6245\/2965\/files\/1_fe12959c-6db5-4ad5-b727-b889e1b72222.png?v=1707419826\" alt=\"\"\u003e\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003ch3\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0652\/6245\/2965\/files\/2_f3e77618-e752-433d-ab2b-c224b15c0f99.png?v=1707419846\" alt=\"\"\u003e\u003c\/h3\u003e\n\u003ch3\u003e\u003cimg height=\"646\" width=\"646\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0652\/6245\/2965\/files\/3_a2a0d476-0328-4856-8db6-315e9e23810c.png?v=1707419871\" alt=\"\"\u003e\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"value\"\u003e\n\u003ch3\u003eTechnical Specifications\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"value\"\u003e\n\u003ctable style=\"box-sizing: border-box; border-color: #ececec; border-spacing: 0px; margin-bottom: 1em; width: 1050px; color: #777777; font-family: 'Roboto Condensed', sans-serif; font-size: medium; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: #ffffff; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;\"\u003e\n\u003ctbody style=\"box-sizing: border-box;\"\u003e\n\u003ctr style=\"box-sizing: border-box;\"\u003e\n\u003ctd style=\"box-sizing: border-box; border-bottom: 1px solid #ececec; font-size: 0.9em; line-height: 1.3; padding: 0.5em 0.5em 0.5em 0px; text-align: left; color: #666666;\"\u003e\u003cstrong style=\"box-sizing: border-box; font-weight: bolder;\"\u003eAperture\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"box-sizing: border-box; border-bottom: 1px solid #ececec; font-size: 0.9em; line-height: 1.3; padding: 0.5em 0px 0.5em 0.5em; text-align: left; color: #666666;\"\u003e81mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"box-sizing: border-box;\"\u003e\n\u003ctd style=\"box-sizing: border-box; border-bottom: 1px solid #ececec; font-size: 0.9em; line-height: 1.3; padding: 0.5em 0.5em 0.5em 0px; text-align: left; color: #666666;\"\u003e\u003cstrong style=\"box-sizing: border-box; font-weight: bolder;\"\u003eFocal Length\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"box-sizing: border-box; border-bottom: 1px solid #ececec; font-size: 0.9em; line-height: 1.3; padding: 0.5em 0px 0.5em 0.5em; text-align: left; color: #666666;\"\u003e478mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"box-sizing: border-box;\"\u003e\n\u003ctd style=\"box-sizing: border-box; border-bottom: 1px solid #ececec; font-size: 0.9em; line-height: 1.3; padding: 0.5em 0.5em 0.5em 0px; text-align: left; color: #666666;\"\u003e\u003cstrong style=\"box-sizing: border-box; font-weight: bolder;\"\u003eFocal Ratio\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"box-sizing: border-box; border-bottom: 1px solid #ececec; font-size: 0.9em; line-height: 1.3; padding: 0.5em 0px 0.5em 0.5em; text-align: left; color: #666666;\"\u003ef\/5.9\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"box-sizing: border-box;\"\u003e\n\u003ctd style=\"box-sizing: border-box; border-bottom: 1px solid #ececec; font-size: 0.9em; line-height: 1.3; padding: 0.5em 0.5em 0.5em 0px; text-align: left; color: #666666;\"\u003e\u003cstrong style=\"box-sizing: border-box; font-weight: bolder;\"\u003eCamera Format\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"box-sizing: border-box; border-bottom: 1px solid #ececec; font-size: 0.9em; line-height: 1.3; padding: 0.5em 0px 0.5em 0.5em; text-align: left; color: #666666;\"\u003eAPS-C, Full Frame\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"box-sizing: border-box;\"\u003e\n\u003ctd style=\"box-sizing: border-box; border-bottom: 1px solid #ececec; font-size: 0.9em; line-height: 1.3; padding: 0.5em 0.5em 0.5em 0px; text-align: left; color: #666666;\"\u003e\u003cstrong style=\"box-sizing: border-box; font-weight: bolder;\"\u003eFocuser\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"box-sizing: border-box; border-bottom: 1px solid #ececec; font-size: 0.9em; line-height: 1.3; padding: 0.5em 0px 0.5em 0.5em; text-align: left; color: #666666;\"\u003e2.5″ R\u0026amp;P focuser\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"box-sizing: border-box;\"\u003e\n\u003ctd style=\"box-sizing: border-box; border-bottom: 1px solid #ececec; font-size: 0.9em; line-height: 1.3; padding: 0.5em 0.5em 0.5em 0px; text-align: left; color: #666666;\"\u003e\u003cstrong style=\"box-sizing: border-box; font-weight: bolder;\"\u003eImage Circle\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"box-sizing: border-box; border-bottom: 1px solid #ececec; font-size: 0.9em; line-height: 1.3; padding: 0.5em 0px 0.5em 0.5em; text-align: left; color: #666666;\"\u003e\u0026gt;Full Frame\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"box-sizing: border-box;\"\u003e\n\u003ctd style=\"box-sizing: border-box; border-bottom: 1px solid #ececec; font-size: 0.9em; line-height: 1.3; padding: 0.5em 0.5em 0.5em 0px; text-align: left; color: #666666;\"\u003e\u003cstrong style=\"box-sizing: border-box; font-weight: bolder;\"\u003eRecommended Flattener\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"box-sizing: border-box; border-bottom: 1px solid #ececec; font-size: 0.9em; line-height: 1.3; padding: 0.5em 0px 0.5em 0.5em; text-align: left; color: #666666;\"\u003eFLAT6AIII\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"box-sizing: border-box;\"\u003e\n\u003ctd style=\"box-sizing: border-box; border-bottom: 1px solid #ececec; font-size: 0.9em; line-height: 1.3; padding: 0.5em 0.5em 0.5em 0px; text-align: left; color: #666666;\"\u003e\u003cstrong style=\"box-sizing: border-box; font-weight: bolder;\"\u003eTube Length\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"box-sizing: border-box; border-bottom: 1px solid #ececec; font-size: 0.9em; line-height: 1.3; padding: 0.5em 0px 0.5em 0.5em; text-align: left; color: #666666;\"\u003e380mm (Fully Retracted)\n\u003cp style=\"box-sizing: border-box; margin: 0.5em 0px; overflow-wrap: break-word;\"\u003e450mm (Fully Extended)\u003c\/p\u003e\n\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"box-sizing: border-box;\"\u003e\n\u003ctd style=\"box-sizing: border-box; border-bottom: 1px solid #ececec; font-size: 0.9em; line-height: 1.3; padding: 0.5em 0.5em 0.5em 0px; text-align: left; color: #666666;\"\u003e\u003cstrong style=\"box-sizing: border-box; font-weight: bolder;\"\u003eTube Weight\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"box-sizing: border-box; border-bottom: 1px solid #ececec; font-size: 0.9em; line-height: 1.3; padding: 0.5em 0px 0.5em 0.5em; text-align: left; color: #666666;\"\u003e3.95kg\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch2\u003e0.8x Reducer Flattener Specification\u003c\/h2\u003e\n\u003ctable style=\"box-sizing: border-box; border-color: #ececec; border-spacing: 0px; margin-bottom: 1em; width: 1050px; color: #777777; font-family: 'Roboto Condensed', sans-serif; font-size: medium; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: #ffffff; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;\"\u003e\n\u003ctbody style=\"box-sizing: border-box;\"\u003e\n\u003ctr style=\"box-sizing: border-box;\"\u003e\n\u003ctd style=\"box-sizing: border-box; border-bottom: 1px solid #ececec; font-size: 0.9em; line-height: 1.3; padding: 0.5em 0.5em 0.5em 0px; text-align: left; color: #666666;\"\u003e\u003cstrong style=\"box-sizing: border-box; font-weight: bolder;\"\u003eTelescope Side Connection\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"box-sizing: border-box; border-bottom: 1px solid #ececec; font-size: 0.9em; line-height: 1.3; padding: 0.5em 0px 0.5em 0.5em; text-align: left; color: #666666;\"\u003eM63x1 Thread- Male\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"box-sizing: border-box;\"\u003e\n\u003ctd style=\"box-sizing: border-box; border-bottom: 1px solid #ececec; font-size: 0.9em; line-height: 1.3; padding: 0.5em 0.5em 0.5em 0px; text-align: left; color: #666666;\"\u003e\u003cstrong style=\"box-sizing: border-box; font-weight: bolder;\"\u003eCamera Side Connection\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"box-sizing: border-box; border-bottom: 1px solid #ececec; font-size: 0.9em; line-height: 1.3; padding: 0.5em 0px 0.5em 0.5em; text-align: left; color: #666666;\"\u003eM48x0.75 Thread- Male\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"box-sizing: border-box;\"\u003e\n\u003ctd style=\"box-sizing: border-box; border-bottom: 1px solid #ececec; font-size: 0.9em; line-height: 1.3; padding: 0.5em 0.5em 0.5em 0px; text-align: left; color: #666666;\"\u003e\u003cstrong style=\"box-sizing: border-box; font-weight: bolder;\"\u003eBack Focus\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"box-sizing: border-box; border-bottom: 1px solid #ececec; font-size: 0.9em; line-height: 1.3; padding: 0.5em 0px 0.5em 0.5em; text-align: left; color: #666666;\"\u003eGT71: 64.1mm\n\u003cp style=\"box-sizing: border-box; margin: 0.5em 0px; overflow-wrap: break-word;\"\u003eGT81: 62.1mm\u003c\/p\u003e\n\u003cp style=\"box-sizing: border-box; margin: 0.5em 0px; overflow-wrap: break-word;\"\u003eZ81: 60.2mm\u003c\/p\u003e\n\u003cp style=\"box-sizing: border-box; margin: 0.5em 0px; overflow-wrap: break-word;\"\u003eZ103: 57.5mm\u003c\/p\u003e\n\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"box-sizing: border-box;\"\u003e\n\u003ctd style=\"box-sizing: border-box; border-bottom: 1px solid #ececec; font-size: 0.9em; line-height: 1.3; padding: 0.5em 0.5em 0.5em 0px; text-align: left; color: #666666;\"\u003e\u003cstrong style=\"box-sizing: border-box; font-weight: bolder;\"\u003eImage Circle\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"box-sizing: border-box; border-bottom: 1px solid #ececec; font-size: 0.9em; line-height: 1.3; padding: 0.5em 0px 0.5em 0.5em; text-align: left; color: #666666;\"\u003eGT71: 44.4mm\n\u003cp style=\"box-sizing: border-box; margin: 0.5em 0px; overflow-wrap: break-word;\"\u003eGT81: 44.4mm\u003c\/p\u003e\n\u003cp style=\"box-sizing: border-box; margin: 0.5em 0px; overflow-wrap: break-word;\"\u003eZ81: 44.3mm\u003c\/p\u003e\n\u003cp style=\"box-sizing: border-box; margin: 0.5em 0px; overflow-wrap: break-word;\"\u003eZ103: 43.1mm\u003c\/p\u003e\n\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003cp\u003e \u003c\/p\u003e\n\u003ch3\u003e\u003cbr\u003e\u003c\/h3\u003e\n\u003ch3\u003eIn the Box\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eWilliam Optics Gran Turismo 81 IV - USED\u003c\/li\u003e\n\u003cli\u003eBahtinov Mask\u003c\/li\u003e\n\u003cli\u003eRings\u003c\/li\u003e\n\u003cli\u003eSlide-Base Handle\u003c\/li\u003e\n\u003cli\u003e50mm William Optics Guide scope, Uni-guide\u003c\/li\u003e\n\u003cli\u003eSoft Carrying Case with customized foam\u003c\/li\u003e\n\u003cli\u003e2'' William Optics Star diagonal\u003c\/li\u003e\n\u003cli\u003e0.8x Flattener Reducer.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cstrong\u003eNo dovetail included.\u003c\/strong\u003e\u003c\/p\u003e\n\u003ch3\u003eWarranty \u0026amp; Manuals\u003c\/h3\u003e\n\u003cp\u003e\u003ca rel=\"noopener\" href=\"https:\/\/istronomyplus.com\/pages\/william-optics-warranty\" target=\"_blank\"\u003eWilliam Optics 2-Year Warranty\u003c\/a\u003e\u003c\/p\u003e\n\u003cp\u003e\u003ca rel=\"noopener\" href=\"https:\/\/istronomyplus.com\/pages\/william-optics-f-a-q\" target=\"_blank\"\u003eWilliam Optics F.A.Q\u003c\/a\u003e\u003c\/p\u003e\n\u003c\/div\u003e","brand":"William Optics","offers":[{"title":"Default Title","offer_id":46750504845541,"sku":"WO-F81GTIVRD-HAL","price":1000.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0652\/6245\/2965\/files\/IMG_20250510_152936_881.jpg?v=1777043666","url":"https:\/\/istronomyplus.com\/products\/william-optics-gran-turismo-81-iv-triplet-apo-f-5-9-used-f81gtivrd-u","provider":"Astronomy Plus – Telescopes \u0026 Astrophotography Canada","version":"1.0","type":"link"}