{"id":33729,"date":"2025-11-14T14:36:19","date_gmt":"2025-11-14T13:36:19","guid":{"rendered":"https:\/\/www.telescoop.nl\/?post_type=product&#038;p=33729"},"modified":"2026-09-10T14:38:41","modified_gmt":"2026-09-10T12:38:41","slug":"william-optics-redcat-91-448-apo-wifd-red-ota","status":"publish","type":"product","link":"https:\/\/www.telescoop.nl\/en\/william-optics-redcat-91-448-apo-wifd-red-ota\/","title":{"rendered":"William Optics RedCat 91\/448 APO WIFD Red OTA"},"content":{"rendered":"<h2 class=\"wp-block-heading has-text-align-center\"><strong>RedCat 91: the classic red version of the Cat 91<\/strong><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">The <strong>William Optics RedCat 91 WIFD<\/strong> brings the Cat 91 optics in the classic red RedCat version. The Petzval design with FPL53 and FPL51 glass provides a color-pure, sharp image across the entire field, up to full-frame size. Suitable for astrophotography and nature photography.<\/p>\n\n\n\n<figure class=\"wp-block-gallery has-nested-images columns-default is-cropped wp-block-gallery-1 is-layout-flex wp-block-gallery-is-layout-flex\">\n<figure class=\"wp-block-image size-large\"><img decoding=\"async\" data-id=\"33730\" src=\"https:\/\/www.telescoop.nl\/wp-content\/uploads\/2025\/11\/William-Optics-AP-91-448-91-Apochromatische-refractor-RedCat-WIFD-OTA-4.jpg\" alt=\"William Optics RedCat 91 WIFD Apochromatic Astrograph, Full Frame\" class=\"wp-image-33730\" title=\"\"><\/figure>\n<\/figure>\n\n\n\n<div class=\"wp-block-columns is-layout-flex wp-container-core-columns-is-layout-8d39b2df wp-block-columns-is-layout-flex\">\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" src=\"https:\/\/www.telescoop.nl\/wp-content\/uploads\/2025\/11\/William-Optics-AP-91-448-91-Apochromatische-refractor-RedCat-WIFD-OTA-1.jpg\" alt=\"The RedCat 91 WIFD with M48 and M54 adapters\" class=\"wp-image-33733\" title=\"\"><\/figure>\n<\/div>\n\n\n\n<div class=\"wp-block-column is-layout-flow wp-block-column-is-layout-flow\">\n<h4 class=\"wp-block-heading\">Fast optics, solid base<\/h4>\n\n\n\n<p class=\"wp-block-paragraph\">With f\/4.9 and a 448mm focal length, you capture a lot of light: short exposures, less noise, and more detail in medium-sized nebulae and galaxies. The M48 and M54 camera adapters directly connect common camera trains, and the internal WIFD focuser maintains constant balance. The Bahtinov mask is located in the lens cap.<\/p>\n<\/div>\n<\/div>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>In the box<\/strong><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Optical tube Cat 91\/448 with WIFD focuser<\/li>\n\n\n\n<li>M48 and M54 Camera Adapters<\/li>\n\n\n\n<li>Dovetail pliers<\/li>\n\n\n\n<li>Integrated Bahtinov mask in the lens cap<\/li>\n\n\n\n<li>Nylon tote bag<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>Featured accessories<\/strong><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">A <a href=\"https:\/\/www.telescoop.nl\/en\/telescope-accessories\/astro-photography\/other-astrophotography-accessories\/\">William Optics UniGuide 50mm Guidescope<\/a> (from 189 euros) is the fitting guide for this class. The M48 and M54 connectors directly accept common William Optics camera adapters.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">For whom yes, for whom no<\/h4>\n\n\n\n<p class=\"wp-block-paragraph\">For: astrophotographers who want the Cat 91 optics in the recognizable red finish, with a complete basic setup. Not for: those who want a rotator and tilt adapter as standard; the BlackCat 91 WIFD includes those for the same price.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>Specifications<\/strong><\/h3>\n\n\n\n<figure class=\"wp-block-table\"><table><tbody><tr><td>Optical design<\/td><td>Apochromat, Petzval (FPL53 and FPL51)<\/td><\/tr><tr><td>Opening<\/td><td>91 millimeters<\/td><\/tr><tr><td>Focal length<\/td><td>448 mm<\/td><\/tr><tr><td>Opening ratio<\/td><td>f\/4,9<\/td><\/tr><tr><td>Focuser<\/td><td>WIFD (intern)<\/td><\/tr><tr><td>Camera connection<\/td><td>M48 and M54<\/td><\/tr><tr><td>Field of view<\/td><td>Flat to full-frame<\/td><\/tr><tr><td>Execution<\/td><td>OTA (loose tube)<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">Unsure about the right tube for your camera and mount? The <a href=\"https:\/\/www.telescoop.nl\/en\/telescope-selection-aid\/\">telescope selection aid<\/a> helps you choose. Also view all <a href=\"https:\/\/www.telescoop.nl\/en\/telescopes\/refracting-telescopes\/\">Refracting telescopes<\/a> and the full range of <a href=\"https:\/\/www.telescoop.nl\/en\/brands\/william-optics\/\">William Optics<\/a>.<\/p>","protected":false},"excerpt":{"rendered":"<p>William Optics RedCat 91 WIFD: Petzval apochromat 91\/448 f\/4.9 in the red finish, with M48\/M54 adapters and internal focuser. Supplied with dovetail bar, Bahtinov mask, and carrying case.<\/p>","protected":false},"featured_media":97260,"comment_status":"open","ping_status":"closed","template":"","meta":{"_acf_changed":false},"product_brand":[643],"product_cat":[51,428,3175,567],"product_tag":[],"class_list":["post-33729","product","type-product","status-publish","has-post-thumbnail","product_brand-william-optics","product_cat-telescopen","product_cat-telescopen-voor-astrofotografie","product_cat-refractor-ota","product_cat-refractor-telescopen","first","instock","taxable","shipping-taxable","purchasable","product-type-simple"],"bundled_by":[],"bundle_stock_status":"instock","bundle_stock_quantity":null,"bundle_virtual":false,"bundle_layout":"","bundle_add_to_cart_form_location":"","bundle_editable_in_cart":false,"bundle_sold_individually_context":"","bundle_item_grouping":"","bundle_min_size":"","bundle_max_size":"","bundle_price":[],"bundled_items":[],"bundle_sell_ids":[34033,33941,33946,34082],"acf":[],"jetpack_sharing_enabled":true,"jetpack-related-posts":[{"id":33717,"url":"https:\/\/www.telescoop.nl\/en\/william-optics-blackcat-91-448-apo-wifd-ota\/","url_meta":{"origin":33729,"position":0},"title":"William Optics BlackCat 91\/448 APO WIFD OTA","author":"","date":"14-11-2025","format":false,"excerpt":"William Optics BlackCat 91 WIFD: Petzval apochromat 91\/448 f\/4.9 with rotator, tilt flange, and M48\/M54 adapters. Color-pure, flat image up to full-frame. Supplied with dovetail bar, Bahtinov mask, and carrying case.","rel":"","context":"Similar post","block_context":{"text":"Similar post","link":""},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2025\/11\/William-Optics-AP-91-448-91-Apochromatische-refractor-BlackCat-WIFD-OTA-10.jpg?resize=350%2C200&ssl=1","width":350,"height":200},"classes":[]},{"id":33664,"url":"https:\/\/www.telescoop.nl\/en\/william-optics-ap-51-250-apochromatische-refractor-spacecat-wifd-ota\/","url_meta":{"origin":33729,"position":1},"title":"William Optics AP 51\/250 Apochromatic Refractor SpaceCat WIFD OTA","author":"","date":"14-11-2025","format":false,"excerpt":"William Optics SpaceCat 51 WIFD: the same f\/4.9 Petzval optics as the RedCat 51 in the SpaceCat version, featuring an internal focuser. Supplied with a Bahtinov mask, dovetail bar, and carrying case.","rel":"","context":"Similar post","block_context":{"text":"Similar post","link":""},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2025\/11\/William-Optics-AP-51250-Apochromatische-refractor-SpaceCat-WIFD-OTA-1.jpg?resize=350%2C200&ssl=1","width":350,"height":200},"classes":[]},{"id":33659,"url":"https:\/\/www.telescoop.nl\/en\/william-optics-ap-51-250-apochromatische-refractor-redcat-wifd\/","url_meta":{"origin":33729,"position":2},"title":"William Optics AP 51\/250 Apochromatic Refractor RedCat WIFD OTA","author":"","date":"14-11-2025","format":false,"excerpt":"William Optics RedCat 51 WIFD: the most famous compact astrograph with a four-element Petzval optical design (FPL53\/FPL51) and internal focuser. Flat, color-corrected image up to full-frame. Delivered with Bahtinov mask, prism rail, and carrying bag.","rel":"","context":"Similar post","block_context":{"text":"Similar post","link":""},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2025\/11\/William-Optics-AP-51250-Apochromatische-refractor-RedCat-WIFD-4.jpg?resize=350%2C200&ssl=1","width":350,"height":200},"classes":[]},{"id":33652,"url":"https:\/\/www.telescoop.nl\/en\/william-optics-ap-51-178-apochromatische-refractor-minicat-wifd-ota\/","url_meta":{"origin":33729,"position":3},"title":"William Optics AP 51\/178 Apochromatic refractor MiniCat WIFD OTA","author":"","date":"14-11-2025","format":false,"excerpt":"William Optics MiniCat 51\/178 WIFD: ultra-compact f\/3.5 apochromat with internal focuser for wide-field astrophotography. Supplied with Bahtinov mask, dew shield, Arca\/Vixen dovetail, and carrying case.","rel":"","context":"Similar post","block_context":{"text":"Similar post","link":""},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2025\/11\/William-Optics-AP-51178-Apochromatische-refractor-MiniCat-WIFD-OTA-1.jpg?resize=350%2C200&ssl=1","width":350,"height":200},"classes":[]},{"id":33684,"url":"https:\/\/www.telescoop.nl\/en\/william-optics-ap-71-350-71-apochromatische-refractor-redcat-ota\/","url_meta":{"origin":33729,"position":4},"title":"William Optics AP 71\/350 71 Apochromatic Refractor RedCat OTA","author":"","date":"14-11-2025","format":false,"excerpt":"William Optics RedCat 71: Petzval apochromat 71\/350 f\/4.9 with a flat field up to full-frame. Includes Bahtinov mask in the lens cap, Vixen\/Arca dovetail, and carrying bag.","rel":"","context":"Similar post","block_context":{"text":"Similar post","link":""},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2025\/11\/William-Optics-AP-71-350-71-Apochromatische-refractor-RedCat-OTA-14.jpg?resize=350%2C200&ssl=1","width":350,"height":200},"classes":[]},{"id":33699,"url":"https:\/\/www.telescoop.nl\/en\/william-optics-ap-71-350-71-apochromatische-refractor-redcat-wifd\/","url_meta":{"origin":33729,"position":5},"title":"William Optics AP 71\/350 71 Apochromatic Refractor RedCat WIFD OTA","author":"","date":"14-11-2025","format":false,"excerpt":"William Optics RedCat 71 WIFD: Petzval apochromat 71\/350 f\/4.9 with internal WIFD focuser. Flat, color-pure image up to full-frame. Delivered with Bahtinov mask, Arca\/Vixen dovetail, and carrying case.","rel":"","context":"Similar post","block_context":{"text":"Similar post","link":""},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2025\/11\/William-Optics-AP-71-350-71-Apochromatische-refractor-RedCat-WIFD-9.jpg?resize=350%2C200&ssl=1","width":350,"height":200},"classes":[]}],"_links":{"self":[{"href":"https:\/\/www.telescoop.nl\/en\/wp-json\/wp\/v2\/product\/33729","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.telescoop.nl\/en\/wp-json\/wp\/v2\/product"}],"about":[{"href":"https:\/\/www.telescoop.nl\/en\/wp-json\/wp\/v2\/types\/product"}],"replies":[{"embeddable":true,"href":"https:\/\/www.telescoop.nl\/en\/wp-json\/wp\/v2\/comments?post=33729"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.telescoop.nl\/en\/wp-json\/wp\/v2\/media\/97260"}],"wp:attachment":[{"href":"https:\/\/www.telescoop.nl\/en\/wp-json\/wp\/v2\/media?parent=33729"}],"wp:term":[{"taxonomy":"product_brand","embeddable":true,"href":"https:\/\/www.telescoop.nl\/en\/wp-json\/wp\/v2\/product_brand?post=33729"},{"taxonomy":"product_cat","embeddable":true,"href":"https:\/\/www.telescoop.nl\/en\/wp-json\/wp\/v2\/product_cat?post=33729"},{"taxonomy":"product_tag","embeddable":true,"href":"https:\/\/www.telescoop.nl\/en\/wp-json\/wp\/v2\/product_tag?post=33729"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}