{"id":33986,"date":"2025-11-16T11:53:49","date_gmt":"2025-11-16T10:53:49","guid":{"rendered":"https:\/\/www.telescoop.nl\/?post_type=product&#038;p=33986"},"modified":"2026-08-25T15:11:36","modified_gmt":"2026-08-25T13:11:36","slug":"william-optics-4-extension-piece-for-flat-gt","status":"publish","type":"product","link":"https:\/\/www.telescoop.nl\/en\/william-optics-4-verlengstuk-voor-flat-gt\/","title":{"rendered":"William Optics 4 Extension for Flat GT"},"content":{"rendered":"<h2 class=\"wp-block-heading has-text-align-center\"><strong>William Optics 4 Extension Tube for Flat GT: Custom backfocus for your Flat GT train<\/strong><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">This William Optics extension tube brings your camera train to the correct length when working with the Flat GT and lacking backfocus. With 67 mm (2.6 inches) of optical length and M92 threads on both sides, everything is fully screwed together, without play or tilt.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">In photography, a geared tripod head is the only route to repeatable sharpness: your camera stays level, your framing holds firm, and corner stars remain round.<\/p>\n\n\n\n<figure class=\"wp-block-gallery has-nested-images columns-3 is-cropped wp-block-gallery-1 is-layout-flex wp-block-gallery-is-layout-flex\"><figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/www.telescoop.nl\/wp-content\/uploads\/2025\/11\/William-Optics-4-Verlengstuk-voor-Flat-GT-1.jpg\" alt=\"William Optics 67 mm extension tube M92 for Flat GT\" title=\"\"><\/figure><figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/www.telescoop.nl\/wp-content\/uploads\/2025\/11\/William-Optics-4-Verlengstuk-voor-Flat-GT-2.jpg\" alt=\"William Optics 67 mm extension tube M92 for Flat GT\" title=\"\"><\/figure><\/figure>\n\n\n\n<h3 class=\"wp-block-heading\">Features<\/h3>\n\n\n\n<ul class=\"wp-block-list\"><li>67 mm (2.6 inch) optical length<\/li><li>M92 thread on both sides, completely tilt-free<\/li><li>For achieving the correct backfocus in Flat GT setups<\/li><li>Rigid, durable construction<\/li><\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Compatibility<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">For camera trains with M92 connections around the William Optics Flat GT. Measure your required backfocus before ordering.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Specifications<\/h3>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><tbody><tr><td><strong>Optical length<\/strong><\/td><td>67 mm (2.6 inches)<\/td><\/tr><tr><td><strong>Thread<\/strong><\/td><td>M92 on both sides<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">You can find more accessories for this brand at the <a href=\"\/en\/brands\/william-optics\/\">William Optics brand page<\/a>.<\/p>","protected":false},"excerpt":{"rendered":"<p>William Optics Extension Tube for Flat GT: 67 mm optical length with M92 thread on both sides, for achieving correct back focus.<\/p>","protected":false},"featured_media":97444,"comment_status":"open","ping_status":"closed","template":"","meta":{"_acf_changed":false},"product_brand":[643],"product_cat":[56,499],"product_tag":[],"class_list":["post-33986","product","type-product","status-publish","has-post-thumbnail","product_brand-william-optics","product_cat-telescoop-accessoires","product_cat-adapters","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":[34224],"acf":[],"jetpack_sharing_enabled":true,"jetpack-related-posts":[{"id":34224,"url":"https:\/\/www.telescoop.nl\/en\/william-optics-flat-gt-flattener-gran-turismo-refractor-2-inch\/","url_meta":{"origin":33986,"position":0},"title":"William Optics Flat GT Flattener for GranTurismo Refractor","author":"","date":"17-11-2025","format":false,"excerpt":"William Optics Flat GT flattener for the GranTurismo 71 and 81: M63 telescope side, M48 camera side with filter thread, full-frame correction, and only 22 mm long.","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-Flat-GT-1.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":33986,"position":1},"title":"William Optics GranTurismo 81\/478 APO IV OTA Red","author":"","date":"15-11-2025","format":false,"excerpt":"Apochromatische refractor (losse buis) van 81 mm met 478 mm brandpunt (f\/5,9): een triplet-objectief met FPL-53-glas, buis ongeveer 3,9 kg. Waarvoor: visueel kijken en astrofotografie; met APS-C 2,8 bij 1,9 graad, met de 0,8x reducer 3,5 bij 2,3 graad.Montering: zwaluwstaart met Vixen- en Arca-Swiss-profiel; reken fotografisch op 8 kg draagvermogen,\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-OTAWilliam-Optics-AP-81478-81-Apochromatische-refractor-Gran-Turismo-IV-OTA-2.jpg?resize=350%2C200&ssl=1","width":350,"height":200},"classes":[]},{"id":34298,"url":"https:\/\/www.telescoop.nl\/en\/william-optics-flat68iii-flattener\/","url_meta":{"origin":33986,"position":2},"title":"William Optics Flat68III Flattener","author":"","date":"17-11-2025","format":false,"excerpt":"William Optics Flat68III flattener: Ohara glass with full FMC coating, adjustable back focus with locking ring, M92 telescope side, T2 camera side, and integrated M48 filter thread.","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-Flat68III-Flattener-1.jpg?resize=350%2C200&ssl=1","width":350,"height":200},"classes":[]},{"id":33971,"url":"https:\/\/www.telescoop.nl\/en\/william-optics-6a-adapters-voor-flattener\/","url_meta":{"origin":33986,"position":3},"title":"William Optics 6A Adapters for Flattener\u00a0","author":"","date":"15-11-2025","format":false,"excerpt":"William Optics 6A adapter from M92 to M63: threaded, tilt-free coupling for the Flat6A and Flat6A III flatteners.","rel":"","context":"Similar post","block_context":{"text":"Similar post","link":""},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":34170,"url":"https:\/\/www.telescoop.nl\/en\/william-optics-m92-rotator\/","url_meta":{"origin":33986,"position":4},"title":"William Optics M92 Rotator\u00a0","author":"","date":"17-11-2025","format":false,"excerpt":"William Optics M92 rotator for 3-inch focusers: 360-degree camera rotation with M92 and M83 threads. Frame without losing focus or alignment.","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-Rotator-M92-2.jpg?resize=350%2C200&ssl=1","width":350,"height":200},"classes":[]},{"id":34222,"url":"https:\/\/www.telescoop.nl\/en\/william-optics-flat7a-adjustable-flattener-reducer\/","url_meta":{"origin":33986,"position":5},"title":"William Optics Flat7A Adjustable Flattener Reducer","author":"","date":"17-11-2025","format":false,"excerpt":"William Optics Flat7A adjustable 0.8x flattener-reducer: Ohara triplet with FMC coating, M92 telescope side, T2 camera side and M48 filter thread. For f\/5 to f\/7 refractors.","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-Flat7A-Adjustable-Flattener-Reducer-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\/33986","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=33986"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.telescoop.nl\/en\/wp-json\/wp\/v2\/media\/97444"}],"wp:attachment":[{"href":"https:\/\/www.telescoop.nl\/en\/wp-json\/wp\/v2\/media?parent=33986"}],"wp:term":[{"taxonomy":"product_brand","embeddable":true,"href":"https:\/\/www.telescoop.nl\/en\/wp-json\/wp\/v2\/product_brand?post=33986"},{"taxonomy":"product_cat","embeddable":true,"href":"https:\/\/www.telescoop.nl\/en\/wp-json\/wp\/v2\/product_cat?post=33986"},{"taxonomy":"product_tag","embeddable":true,"href":"https:\/\/www.telescoop.nl\/en\/wp-json\/wp\/v2\/product_tag?post=33986"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}