{"product_id":"used-william-optics-cat-91","title":"Used William Optics Cat 91","description":"\u003cp\u003eThis is a used WO Cat 91 in excellent condition. The optics are very clean and the body is unmarked. Includes the original bag, cap, screws, and certificate. We can ship this item!\u003cstrong\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cbr\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cimg style=\"border-radius: 20px;\" alt=\"\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/1979\/5379\/files\/redcat-91-wifd-hero.webp?v=1765566029\"\u003e\u003c\/p\u003e\n\u003ch1 class=\"h3\" style=\"text-align: center;\"\u003eThe cat with medium-format soul\u003c\/h1\u003e\n\u003cdiv\u003e\n\u003cp\u003eAn advanced apochromatic refractor tailored for full-frame and medium-format cameras. This latest addition to the RedCat series combines portability with superior optical performance, making it a versatile tool for capturing breathtaking detail in deep-sky objects.\u003c\/p\u003e\n\u003cp\u003e \u003c\/p\u003e\n\u003c\/div\u003e\n\u003ctable style=\"border-radius: 20px;\" width=\"100%\" bgcolor=\"black\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003e \u003cimg alt=\"\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/1979\/5379\/files\/cat-91-Spec-icon__1.avif?v=1765047847\" style=\"display: block; margin-left: auto; margin-right: auto;\"\u003e\n\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003cp\u003e \u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003eStep up your astrophotography game with the William Optics RedCat 91, an advanced apochromatic refractor tailored for full-frame and medium-format cameras. This latest addition to the RedCat series combines portability with superior optical performance, making it a versatile tool for capturing breathtaking detail in deep-sky objects.\u003c\/span\u003e\u003c\/p\u003e\n\u003ch3\u003e\u003cspan\u003eHighlights:\u003cbr\u003e\u003c\/span\u003e\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003ePetzval Design, No Backfocus Hassles\u003cbr\u003e\u003c\/strong\u003eThe 5-element Petzval design eliminates the need for backfocus adjustments, providing sharp, edge-to-edge images with pinpoint stars—ideal for wide-field and detailed astrophotography alike.\u003cbr\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eFull-Frame \u0026amp; Medium-Format Ready, No Extra Flattener Needed\u003cbr\u003e\u003c\/strong\u003eWith a large 55mm image circle, the RedCat 91 is perfect for both full-frame and medium-format cameras. Its advanced optics achieve flat-field images without requiring an additional flattener, giving astrophotographers the freedom to capture expansive views with unparalleled clarity.\u003cbr\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eFast f\/4.9 Focal Ratio\u003cbr\u003e\u003c\/strong\u003eThe RedCat 91's fast f\/4.9 focal ratio is designed for bright, vivid captures of galaxies, nebulae, and beyond, ensuring excellent light-gathering power and sharp detail even on faint celestial objects.\u003cbr\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eSeamless WIFD Focusing\u003cbr\u003e\u003c\/strong\u003eEquipped with William Optics' WIFD focuser, the RedCat 91 provides precise, stable focusing without additional adjustments, enhancing the ease of use for both seasoned astrophotographers and beginners.\u003cbr\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003eThe RedCat 91 blends the trusted RedCat heritage with William Optics’ innovative design, making it the ultimate choice for those ready to elevate their night-sky explorations.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/1979\/5379\/files\/Cat-91-WIFD-whatsinbox_1.webp?v=1765566033\" alt=\"\"\u003e\u003c\/span\u003e\u003c\/p\u003e\n\u003ctable class=\"notion-collection-table\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003e\n\u003cdiv class=\"notion-collection-column-title\"\u003e\n\u003cdiv class=\"notion-collection-column-title-body\"\u003eLens Type\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/td\u003e\n\u003ctd\u003e\u003cspan class=\"notion-property notion-property-text\"\u003e5 Elements Advanced Petzval Design\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\n\u003cdiv class=\"notion-collection-column-title\"\u003e\n\u003cdiv class=\"notion-collection-column-title-body\"\u003eFocal Length\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/td\u003e\n\u003ctd\u003e\u003cspan class=\"notion-property notion-property-text\"\u003e448 mm\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\n\u003cdiv class=\"notion-collection-column-title\"\u003e\n\u003cdiv class=\"notion-collection-column-title-body\"\u003eDiameter\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/td\u003e\n\u003ctd\u003e\u003cspan class=\"notion-property notion-property-text\"\u003e91 mm\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\n\u003cdiv class=\"notion-collection-column-title\"\u003e\n\u003cdiv class=\"notion-collection-column-title-body\"\u003eFocal Ratio\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/td\u003e\n\u003ctd\u003e\u003cspan class=\"notion-property notion-property-text\"\u003ef\/4.9\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\n\u003cdiv class=\"notion-collection-column-title\"\u003e\n\u003cdiv class=\"notion-collection-column-title-body\"\u003eImage Circle\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/td\u003e\n\u003ctd\u003e\u003cspan class=\"notion-property notion-property-text\"\u003e55mm\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\n\u003cdiv class=\"notion-collection-column-title\"\u003e\n\u003cdiv class=\"notion-collection-column-title-body\"\u003eFocuser\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/td\u003e\n\u003ctd\u003e\n\u003cdiv class=\"notion-property-multi_select-item notion-item-purple\"\u003eWIFD R\u0026amp;P Focuser\u003c\/div\u003e\n\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\n\u003cdiv class=\"notion-collection-column-title\"\u003e\n\u003cdiv class=\"notion-collection-column-title-body\"\u003eFocuser Travel Length\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/td\u003e\n\u003ctd\u003e\u003cspan class=\"notion-property notion-property-text\"\u003e0-36 mm (Ruler to 40mm)\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\n\u003cdiv class=\"notion-collection-column-title\"\u003e\n\u003cdiv class=\"notion-collection-column-title-body\"\u003eAdapter Included\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/td\u003e\n\u003ctd\u003e\n\u003cdiv class=\"notion-property-multi_select-item notion-item-green\"\u003eTilt Adjuster\u003c\/div\u003e\n\u003cdiv class=\"notion-property-multi_select-item notion-item-yellow\"\u003eRotator\u003c\/div\u003e\n\u003cdiv class=\"notion-property-multi_select-item notion-item-default\"\u003eM63 → M54 Adapter\u003c\/div\u003e\n\u003cdiv class=\"notion-property-multi_select-item notion-item-default\"\u003eM63 → M48 Adapter\u003c\/div\u003e\n\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\n\u003cdiv class=\"notion-collection-column-title\"\u003e\n\u003cdiv class=\"notion-collection-column-title-body\"\u003eOptional Flattener\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/td\u003e\n\u003ctd\u003e\n\u003cdiv class=\"notion-property-multi_select-item notion-item-default\"\u003eNo Flattener Required\u003c\/div\u003e\n\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\n\u003cdiv class=\"notion-collection-column-title\"\u003e\n\u003cdiv class=\"notion-collection-column-title-body\"\u003eCamera Format\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/td\u003e\n\u003ctd\u003e\n\u003cdiv class=\"notion-property-multi_select-item notion-item-red\"\u003eMedium Format (needs additional adapter)\u003c\/div\u003e\n\u003cdiv class=\"notion-property-multi_select-item notion-item-yellow\"\u003eFull Frame\u003c\/div\u003e\n\u003cdiv class=\"notion-property-multi_select-item notion-item-blue\"\u003eAPS-C\u003c\/div\u003e\n\u003cdiv class=\"notion-property-multi_select-item notion-item-purple\"\u003eM4\/3\u003c\/div\u003e\n\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\n\u003cdiv class=\"notion-collection-column-title\"\u003e\n\u003cdiv class=\"notion-collection-column-title-body\"\u003eTotal Weight\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/td\u003e\n\u003ctd\u003e\u003cspan class=\"notion-property notion-property-text\"\u003e6.3 kg \/ 13.89 lbs\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\n\u003cdiv class=\"notion-collection-column-title\"\u003e\n\u003cdiv class=\"notion-collection-column-title-body\"\u003eOTA Weight\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/td\u003e\n\u003ctd\u003e\u003cspan class=\"notion-property notion-property-text\"\u003e4.72 kg \/ 10.41 lbs\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\n\u003cdiv class=\"notion-collection-column-title\"\u003e\n\u003cdiv class=\"notion-collection-column-title-body\"\u003eTube Length\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/td\u003e\n\u003ctd\u003e\u003cspan class=\"notion-property notion-property-text\"\u003e556 mm\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003cp\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/1979\/5379\/files\/Cat91-inthebox.png?v=1765566237\" alt=\"\"\u003e\u003c\/p\u003e\n\u003ch1 style=\"text-align: center;\"\u003eOptical Performance\u003c\/h1\u003e\n\u003cp\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/1979\/5379\/files\/Diagram_Cat-91_1_1.webp?v=1765824041\" alt=\"\"\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/1979\/5379\/files\/Diagram_Cat-91_1-1_1.webp?v=1765824044\" alt=\"\"\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/1979\/5379\/files\/Diagram_Cat-91_2_1.webp?v=1765824047\" alt=\"\"\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/1979\/5379\/files\/Diagram_Cat-91_3_1.webp?v=1765824093\" alt=\"\"\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/1979\/5379\/files\/Diagram_Cat-91_4_1.webp?v=1765824096\" alt=\"\"\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cbr\u003e\u003cimg alt=\"\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/1979\/5379\/files\/FOV-cat91-C-02_3195c3da-bde1-4c80-9f5d-50737fd7d26b.webp?v=1765566508\"\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/1979\/5379\/files\/Cat-91-Gallery-m45.webp?v=1765050595\" alt=\"\"\u003e\u003c\/p\u003e\n\u003ch4\u003e▲ M45 (Full-Frame)\u003c\/h4\u003e\n\u003cp\u003eCat 91 + ZWO ASI 6200MC Pro\u003cbr\u003eCourtesy of Dear Bear\u003c\/p\u003e\n\u003col\u003e\n\u003cli\u003eStacked ( After Process )\u003c\/li\u003e\n\u003cli\u003eOriginal Single Shot Corner Grid\u003c\/li\u003e\n\u003c\/ol\u003e\n\u003cp\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/1979\/5379\/files\/Cat-91-Gallery-m45-single-grid.webp?v=1765050595\" alt=\"\"\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/1979\/5379\/files\/Cat-91-Gallery-Rosette_final.webp?v=1765050595\" alt=\"\"\u003e\u003c\/p\u003e\n\u003cp\u003eNGC 2237 Rosette by \u003cmeta charset=\"utf-8\"\u003e\u003cspan\u003e\u003ca class=\"link\" href=\"https:\/\/youtu.be\/Ly60EQ8eBfM?si=r8bHy_Mclm0mzfOz\"\u003eReynold Edwards\u003c\/a\u003e\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/1979\/5379\/files\/Cat-91-Gallery-Andromeda_final.webp?v=1765050595\" alt=\"\"\u003e\u003c\/span\u003e\u003cspan\u003eM31 Andromeda by \u003cmeta charset=\"utf-8\"\u003e \u003ca class=\"link\" href=\"https:\/\/youtu.be\/Ly60EQ8eBfM?si=r8bHy_Mclm0mzfOz\"\u003eReynold Edwards\u003c\/a\u003e\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e \u003c\/p\u003e\n\u003cp\u003e\u003ca rel=\"noopener\" href=\"https:\/\/support.williamoptics.com\/products\/cat-91-wifd\" target=\"_blank\"\u003e\u003cspan\u003eOnline Manual\u003c\/span\u003e\u003c\/a\u003e\u003c\/p\u003e\n\u003cp\u003e \u003c\/p\u003e","brand":"William Optics","offers":[{"title":"Default Title","offer_id":48362889478403,"sku":"U2606-MD-T-C-91","price":2200.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1979\/5379\/files\/original-618.jpg?v=1781119968","url":"https:\/\/milehighastro.com\/products\/used-william-optics-cat-91","provider":"Mile High Astronomy","version":"1.0","type":"link"}