{"id":33849,"date":"2025-11-15T13:05:18","date_gmt":"2025-11-15T12:05:18","guid":{"rendered":"https:\/\/www.telescoop.nl\/?post_type=product&#038;p=33849"},"modified":"2026-10-13T11:15:20","modified_gmt":"2026-10-13T09:15:20","slug":"william-optics-granturismo-81-478-apo-wifd-ota","status":"publish","type":"product","link":"https:\/\/www.telescoop.nl\/en\/william-optics-granturismo-81-478-apo-wifd-ota\/","title":{"rendered":"William Optics GranTurismo 81\/478 APO WIFD OTA"},"content":{"rendered":"<h2 class=\"wp-block-heading has-text-align-center\"><strong>GT81 WIFD: triplet with internal focuser and built-in rotator<\/strong><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">The <strong>William Optics GranTurismo 81 WIFD<\/strong> is the most advanced GT81: the apochromatic triplet combined with the internal WIFD focuser and a built-in field rotator. Sharp stars, high color purity, and complete control over your composition, without disconnecting the imaging train.<\/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=\"33850\" src=\"https:\/\/www.telescoop.nl\/wp-content\/uploads\/2025\/11\/William-Optics-AP-81-478-81-Apochromatische-refractor-GranTurismo-WIFD-OTA-1.jpg\" alt=\"William Optics GranTurismo 81 WIFD apochromatic triplet refractor, full view\" class=\"wp-image-33850\" 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-81-478-81-Apochromatische-refractor-GranTurismo-WIFD-OTA-6.jpg\" alt=\"The GranTurismo 81 WIFD with internal focuser and rotator\" class=\"wp-image-33855\" 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\">Remaining balance<\/h4>\n\n\n\n<p class=\"wp-block-paragraph\">The internal WIFD focuser does not shift any weight outside the tube: the balance on the mount remains constant, even with a heavy camera. The built-in rotator adjusts the composition precisely without affecting the focus. With a 478 mm brand focal length at f\/5.9, you can photograph nebulae and star fields quickly and consistently; the Bahtinov mask ensures precise focusing.<\/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 GranTurismo 81\/478 with WIFD focuser<\/li>\n\n\n\n<li>Built-in field rotator<\/li>\n\n\n\n<li>Vixen-Style dovetail<\/li>\n\n\n\n<li>Handle<\/li>\n\n\n\n<li>Bahtinov mask<\/li>\n\n\n\n<li>Soft carrier 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\">The <a href=\"https:\/\/www.telescoop.nl\/en\/telescope-accessories\/astro-photography\/other-astrophotography-accessories\/\">William Optics Flat GT flattener<\/a> (329 euro) flattens the field to full-frame; the UniGuide 32 mm guidescope (159 euro) enables long exposures.<\/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: demanding astrophotographers who want the GT81 triplet with internal focuser and rotator as a complete imaging tube. Not: those buying mainly on a budget; the standard GT81 IV delivers the same triplet optics with an external focuser for 400 euros less.<\/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, FPL-53 triplet<\/td><\/tr><tr><td>Opening<\/td><td>81 millimeters<\/td><\/tr><tr><td>Focal length<\/td><td>478 mm<\/td><\/tr><tr><td>Opening ratio<\/td><td>f\/5,9<\/td><\/tr><tr><td>Focuser<\/td><td>WIFD (intern)<\/td><\/tr><tr><td>Rotator<\/td><td>Built-in<\/td><\/tr><tr><td>Focus assist<\/td><td>Bahtinov mask<\/td><\/tr><tr><td>Attachment<\/td><td>Vixen-style dovetail with handle<\/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><strong>This is just the tube (OTA), without mounting and tripod.<\/strong> You can choose the appropriate mounting and the accessories that come with it below.<\/p>\n<p>William Optics GranTurismo 81 WIFD: FPL-53 triplet apochromat 81\/478 f\/5.9 with internal WIFD focuser and built-in field rotator. Supplied with Vixen dovetail, handle, Bahtinov mask, and carrying case.<\/p>","protected":false},"featured_media":97342,"comment_status":"open","ping_status":"closed","template":"","meta":{"_acf_changed":false},"product_brand":[643],"product_cat":[51,428,3175,567],"product_tag":[3352,3353],"class_list":["post-33849","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","product_tag-sterrenkijker","product_tag-sterrenkijkers","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":[90626,27732,32949,34220,15860,34224,34101,34033,33941,33946,34082],"acf":[],"jetpack_sharing_enabled":true,"jetpack-related-posts":[{"id":33843,"url":"https:\/\/www.telescoop.nl\/en\/william-optics-granturismo-81-478-apo-iv-ota-grey\/","url_meta":{"origin":33849,"position":0},"title":"William Optics GranTurismo 81\/478 APO IV OTA","author":"","date":"15-11-2025","format":false,"excerpt":"This is just the tube (OTA), without the mounting and tripod. You can choose the appropriate mounting and the accessories that come with it below. William Optics GranTurismo 81 IV: FPL-53 triplet apochromatic 81\/478 f\/5.9, the same optics and scope as the Gold and Red versions for the best price. With dovetail mount, handle, Bahtinov mask and\u2026","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-81-478-81-Apochromatische-refractor-Gran-Turismo-IV-OTA-3-1.jpg?resize=350%2C200&ssl=1","width":350,"height":200},"classes":[]},{"id":33829,"url":"https:\/\/www.telescoop.nl\/en\/william-optics-granturismo-81-478-apo-iv-gold-ota\/","url_meta":{"origin":33849,"position":1},"title":"William Optics GranTurismo 81\/478 APO IV Gold OTA","author":"","date":"15-11-2025","format":false,"excerpt":"This is just the tube (OTA), without the mounting and tripod. You can choose the appropriate mounting and the accessories that come with it below. William Optics GranTurismo 81 IV Gold: FPL-53 triplet apochromatic 81\/478 f\/5.9 in gold finish. Supplied with Vixen falcon-tail, handle, Bahtinov mask, adapter 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-81-478-81-Apochromatische-refractor-Gran-Turismo-IV-OTA-3.jpg?resize=350%2C200&ssl=1","width":350,"height":200},"classes":[]},{"id":33836,"url":"https:\/\/www.telescoop.nl\/en\/william-optics-granturismo-81-478-apo-iv-ota-rood\/","url_meta":{"origin":33849,"position":2},"title":"William Optics GranTurismo 81\/478 APO IV OTA Red","author":"","date":"15-11-2025","format":false,"excerpt":"This is just the tube (OTA), without the mounting and tripod. You can choose the appropriate mounting and the accessories that come with it below. William Optics GranTurismo 81 IV Red: FPL-53 triplet apochromatic 81\/478 f\/5.9 in red version. Supplied with Vixen eagle-tailed mount, handle, Bahtinov mask, adapter 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-81-478-81-Apochromatische-refractor-Gran-Turismo-IV-OTAWilliam-Optics-AP-81478-81-Apochromatische-refractor-Gran-Turismo-IV-OTA-2.jpg?resize=350%2C200&ssl=1","width":350,"height":200},"classes":[]},{"id":33717,"url":"https:\/\/www.telescoop.nl\/en\/william-optics-blackcat-91-448-apo-wifd-ota\/","url_meta":{"origin":33849,"position":3},"title":"William Optics BlackCat 91\/448 APO WIFD OTA","author":"","date":"14-11-2025","format":false,"excerpt":"This is just the tube (OTA), without the mounting and tripod. You can choose the appropriate mounting and the accessories that come with it below. William Optics BlackCat 91 WIFD: Petzval achromatic lens 91\/448 f\/4.9 with rotator, tilt lens and M48\/M54 adapters. Color purity, flat image up to full-frame. Supplied with dovetail rod, 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":33639,"url":"https:\/\/www.telescoop.nl\/en\/william-optics-ap-108-518-apochromatische-refractor-ultracat-wifd\/","url_meta":{"origin":33849,"position":4},"title":"William Optics AP 108\/518 Apochromatic Refractor UltraCat WIFD OTA","author":"","date":"14-11-2025","format":false,"excerpt":"This is just the tube (OTA), without the mount and tripod. You can choose the appropriate mount and the accessories that come with it below. William Optics UltraCat 108 WIFD: full-frame flagship 108\/518 f\/4.8 with integrated Petzval corrector, rotator, tilt lens and internal focuser. Supplied with Bahtinov mask and Vixen owl tail.","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-Apochromatische-refractor-AP-108-518-UltraCat-WIFD.jpg?resize=350%2C200&ssl=1","width":350,"height":200},"classes":[]},{"id":33886,"url":"https:\/\/www.telescoop.nl\/en\/william-optics-zenithstar-81-559-apo-wifd-goud-ota\/","url_meta":{"origin":33849,"position":5},"title":"William Optics ZenithStar 81\/559 APO WIFD Gold OTA","author":"","date":"15-11-2025","format":false,"excerpt":"This is the tube (OTA) only, without mounting and tripod. A suitable mounting and the accessories that come with it can be selected below. William Optics ZenithStar 81 WIFD Gold: FPL-53 achromatic 81\/559 f\/6.9 with internal focus. Supplied with tube rings, Arca\/Vixen dovetail, handle, Bahtinov mask, adapters 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-81-559-81-Apochromatische-refractor-ZenithStar-WIFD-Goud-OTA-1.jpg?resize=350%2C200&ssl=1","width":350,"height":200},"classes":[]}],"_links":{"self":[{"href":"https:\/\/www.telescoop.nl\/en\/wp-json\/wp\/v2\/product\/33849","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=33849"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.telescoop.nl\/en\/wp-json\/wp\/v2\/media\/97342"}],"wp:attachment":[{"href":"https:\/\/www.telescoop.nl\/en\/wp-json\/wp\/v2\/media?parent=33849"}],"wp:term":[{"taxonomy":"product_brand","embeddable":true,"href":"https:\/\/www.telescoop.nl\/en\/wp-json\/wp\/v2\/product_brand?post=33849"},{"taxonomy":"product_cat","embeddable":true,"href":"https:\/\/www.telescoop.nl\/en\/wp-json\/wp\/v2\/product_cat?post=33849"},{"taxonomy":"product_tag","embeddable":true,"href":"https:\/\/www.telescoop.nl\/en\/wp-json\/wp\/v2\/product_tag?post=33849"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}