{"id":34079,"date":"2025-11-16T16:13:59","date_gmt":"2025-11-16T15:13:59","guid":{"rendered":"https:\/\/www.telescoop.nl\/?post_type=product&p=34079"},"modified":"2026-03-04T16:44:00","modified_gmt":"2026-03-04T15:44:00","slug":"william-optics-243-308mm-bahtinov-focus-mask","status":"publish","type":"product","link":"https:\/\/staging.telescoop.nl\/en\/william-optics-243-308mm-bahtinov-focusmasker\/","title":{"rendered":"William Optics 243-308 mm Bahtinov Focus Mask"},"content":{"rendered":"

Focusing without fuss<\/strong><\/h3>\n\n\n\n

The William Optics 243-308mm focus mask helps you focus quickly and precisely. It is made of optical acrylic glass with 92% light transmission. This keeps your image clear and sharp even with faint stars.<\/p>\n\n\n\n

\n
\"William<\/figure>\n<\/figure>\n\n\n\n

Clear bending pattern<\/strong><\/h3>\n\n\n\n

The mask has a pattern that bends three times stronger than classic metal masks. You can see the lines clearly and find the perfect focus faster.<\/p>\n\n\n\n

Easy to use<\/strong><\/h3>\n\n\n\n

The mask fits telescopes from 243 to 308 mm in diameter. You simply place it over your telescope and you are ready to focus. The acrylic glass provides a clear, high-contrast image.<\/p>\n\n\n\n

\n
\"William<\/figure>\n<\/figure>\n\n\n\n

Specifications<\/strong><\/h3>\n\n\n\n

General<\/strong><\/h4>\n\n\n\n
Feature<\/th>Description<\/th><\/tr><\/thead>
Color<\/td>Transparent<\/td><\/tr>
Material<\/td>Acrylic<\/td><\/tr>
Diameter (mm)<\/td>243-308<\/td><\/tr>
Type<\/td>Mask<\/td><\/tr>
Design<\/td>Focus Mask<\/td><\/tr><\/tbody><\/table><\/figure>","protected":false},"excerpt":{"rendered":"

William Optics 243-308mm comes as a high-quality focus mask made of optical acrylic glass with a light transmittance of 92%, providing an approx. three times brighter diffraction image than classic metal masks. \u00a0<\/p>","protected":false},"featured_media":97506,"comment_status":"open","ping_status":"closed","template":"","meta":{"_acf_changed":false},"product_brand":[643],"product_cat":[51,428],"product_tag":[],"class_list":["post-34079","product","type-product","status-publish","has-post-thumbnail","product_brand-william-optics","product_cat-telescopen","product_cat-telescopen-voor-astrofotografie","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":[],"acf":[],"jetpack_sharing_enabled":true,"jetpack-related-posts":[{"id":34082,"url":"https:\/\/staging.telescoop.nl\/en\/william-optics-75-110mm-bahtinov-mask\/","url_meta":{"origin":34079,"position":0},"title":"William Optics 75-110mm Bahtinov Mask","author":"","date":"16-11-2025","format":false,"excerpt":"William Optics 75-110mm Focus mask Bahtinov comes as a high quality focus mask made of optical acrylic glass with 92% light transmission, providing an approx. three times brighter diffraction image than classic metal masks. \u00a0","rel":"","context":"Similar post","block_context":{"text":"Similar post","link":""},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/staging.telescoop.nl\/wp-content\/uploads\/2025\/11\/William-Optics-75-110mm-Focus-masker-Bahtinov-2.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/staging.telescoop.nl\/wp-content\/uploads\/2025\/11\/William-Optics-75-110mm-Focus-masker-Bahtinov-2.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/staging.telescoop.nl\/wp-content\/uploads\/2025\/11\/William-Optics-75-110mm-Focus-masker-Bahtinov-2.jpg?resize=525%2C300&ssl=1 1.5x, https:\/\/i0.wp.com\/staging.telescoop.nl\/wp-content\/uploads\/2025\/11\/William-Optics-75-110mm-Focus-masker-Bahtinov-2.jpg?resize=700%2C400&ssl=1 2x"},"classes":[]},{"id":34075,"url":"https:\/\/staging.telescoop.nl\/en\/william-optics-172-235mm-bahtinov-focusmasker\/","url_meta":{"origin":34079,"position":1},"title":"William Optics 172-235mm Bahtinov Focus Mask","author":"","date":"16-11-2025","format":false,"excerpt":"William Optics 172-235mm Focus mask Bahtinov comes with adjustable mounting pins for telescopes from 172 to 235mm diameter. \u00a0","rel":"","context":"Similar post","block_context":{"text":"Similar post","link":""},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/staging.telescoop.nl\/wp-content\/uploads\/2025\/11\/William-Optics-172-235mm-Focus-masker-Bahtinov-1.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/staging.telescoop.nl\/wp-content\/uploads\/2025\/11\/William-Optics-172-235mm-Focus-masker-Bahtinov-1.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/staging.telescoop.nl\/wp-content\/uploads\/2025\/11\/William-Optics-172-235mm-Focus-masker-Bahtinov-1.jpg?resize=525%2C300&ssl=1 1.5x, https:\/\/i0.wp.com\/staging.telescoop.nl\/wp-content\/uploads\/2025\/11\/William-Optics-172-235mm-Focus-masker-Bahtinov-1.jpg?resize=700%2C400&ssl=1 2x"},"classes":[]},{"id":34072,"url":"https:\/\/staging.telescoop.nl\/en\/william-optics-105-148mm-bahtinov-focusmasker\/","url_meta":{"origin":34079,"position":2},"title":"William Optics 105-148mm Bahtinov Focus Mask","author":"","date":"16-11-2025","format":false,"excerpt":"William Optics 105-148mm Focus mask Bahtinov comes with adjustable mounting pins for telescopes from 105 to 148mm diameter. \u00a0","rel":"","context":"Similar post","block_context":{"text":"Similar post","link":""},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/staging.telescoop.nl\/wp-content\/uploads\/2025\/11\/William-Optics-105-148mm-Focus-masker-Bahtinov-1.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/staging.telescoop.nl\/wp-content\/uploads\/2025\/11\/William-Optics-105-148mm-Focus-masker-Bahtinov-1.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/staging.telescoop.nl\/wp-content\/uploads\/2025\/11\/William-Optics-105-148mm-Focus-masker-Bahtinov-1.jpg?resize=525%2C300&ssl=1 1.5x, https:\/\/i0.wp.com\/staging.telescoop.nl\/wp-content\/uploads\/2025\/11\/William-Optics-105-148mm-Focus-masker-Bahtinov-1.jpg?resize=700%2C400&ssl=1 2x"},"classes":[]},{"id":33751,"url":"https:\/\/staging.telescoop.nl\/en\/william-optics-fluorostar-132-925-refractor-apo-red-ota\/","url_meta":{"origin":34079,"position":3},"title":"William Optics Fluorostar 132\/925 Refractor APO Red OTA","author":"","date":"14-11-2025","format":false,"excerpt":"William Optics AP 132\/925 comes with Bahtinov focus mask, 3.7\" rotary focuser with 1:10 fine adjustment, Losmandy swallowtail, handle and padded transport bag - a top-of-the-line FPL-53 triplet for razor-sharp astrophotos and visual deep-sky observations. \u00a0","rel":"","context":"Similar post","block_context":{"text":"Similar post","link":""},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/staging.telescoop.nl\/wp-content\/uploads\/2025\/11\/William-Optics-AP-132-925-Apochromatische-refractor-FluoroStar-Red-OTA-1.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/staging.telescoop.nl\/wp-content\/uploads\/2025\/11\/William-Optics-AP-132-925-Apochromatische-refractor-FluoroStar-Red-OTA-1.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/staging.telescoop.nl\/wp-content\/uploads\/2025\/11\/William-Optics-AP-132-925-Apochromatische-refractor-FluoroStar-Red-OTA-1.jpg?resize=525%2C300&ssl=1 1.5x, https:\/\/i0.wp.com\/staging.telescoop.nl\/wp-content\/uploads\/2025\/11\/William-Optics-AP-132-925-Apochromatische-refractor-FluoroStar-Red-OTA-1.jpg?resize=700%2C400&ssl=1 2x"},"classes":[]},{"id":33917,"url":"https:\/\/staging.telescoop.nl\/en\/william-optics-pleiades-68-260-apo-astrograph-ota\/","url_meta":{"origin":34079,"position":4},"title":"William Optics Pleiades 68\/260 APO Astrograph OTA","author":"","date":"15-11-2025","format":false,"excerpt":"William Optics 68 AP 68\/260 comes with an integrated 7-element corrector, WIDF internal focuser, Bahtinov mask, transport bag, Vixen-style dovetail, handle and M48 and M54 camera adapters. \u00a0","rel":"","context":"Similar post","block_context":{"text":"Similar post","link":""},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/staging.telescoop.nl\/wp-content\/uploads\/2025\/11\/William-Optics-68-AP-68-260-Apochromatische-refractor-Pleiades-Astrograph-OTA-6.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/staging.telescoop.nl\/wp-content\/uploads\/2025\/11\/William-Optics-68-AP-68-260-Apochromatische-refractor-Pleiades-Astrograph-OTA-6.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/staging.telescoop.nl\/wp-content\/uploads\/2025\/11\/William-Optics-68-AP-68-260-Apochromatische-refractor-Pleiades-Astrograph-OTA-6.jpg?resize=525%2C300&ssl=1 1.5x, https:\/\/i0.wp.com\/staging.telescoop.nl\/wp-content\/uploads\/2025\/11\/William-Optics-68-AP-68-260-Apochromatische-refractor-Pleiades-Astrograph-OTA-6.jpg?resize=700%2C400&ssl=1 2x"},"classes":[]},{"id":33903,"url":"https:\/\/staging.telescoop.nl\/en\/william-optics-pleiades-111-528-apo-septuplet-astrograph-ota\/","url_meta":{"origin":34079,"position":5},"title":"William Optics Pleiades 111\/528 APO Septuplet Astrograph OTA","author":"","date":"15-11-2025","format":false,"excerpt":"William Optics 111 AP 111\/528 wordt geleverd met een ge\u00efntegreerde 7-lens corrector, WIDF interne focuser, Vixen-Style zwaluwstaart, handvat, Bahtinov-masker, M54 & M48 camera adapters en een zachte draagtas. \u00a0","rel":"","context":"Similar post","block_context":{"text":"Similar post","link":""},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/staging.telescoop.nl\/wp-content\/uploads\/2025\/11\/William-Optics-111-AP-111-528-Apochromatische-refractor-Pleiades-Astrograph-OTA-2.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/staging.telescoop.nl\/wp-content\/uploads\/2025\/11\/William-Optics-111-AP-111-528-Apochromatische-refractor-Pleiades-Astrograph-OTA-2.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/staging.telescoop.nl\/wp-content\/uploads\/2025\/11\/William-Optics-111-AP-111-528-Apochromatische-refractor-Pleiades-Astrograph-OTA-2.jpg?resize=525%2C300&ssl=1 1.5x, https:\/\/i0.wp.com\/staging.telescoop.nl\/wp-content\/uploads\/2025\/11\/William-Optics-111-AP-111-528-Apochromatische-refractor-Pleiades-Astrograph-OTA-2.jpg?resize=700%2C400&ssl=1 2x"},"classes":[]}],"_links":{"self":[{"href":"https:\/\/staging.telescoop.nl\/en\/wp-json\/wp\/v2\/product\/34079","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/staging.telescoop.nl\/en\/wp-json\/wp\/v2\/product"}],"about":[{"href":"https:\/\/staging.telescoop.nl\/en\/wp-json\/wp\/v2\/types\/product"}],"replies":[{"embeddable":true,"href":"https:\/\/staging.telescoop.nl\/en\/wp-json\/wp\/v2\/comments?post=34079"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/staging.telescoop.nl\/en\/wp-json\/wp\/v2\/media\/97506"}],"wp:attachment":[{"href":"https:\/\/staging.telescoop.nl\/en\/wp-json\/wp\/v2\/media?parent=34079"}],"wp:term":[{"taxonomy":"product_brand","embeddable":true,"href":"https:\/\/staging.telescoop.nl\/en\/wp-json\/wp\/v2\/product_brand?post=34079"},{"taxonomy":"product_cat","embeddable":true,"href":"https:\/\/staging.telescoop.nl\/en\/wp-json\/wp\/v2\/product_cat?post=34079"},{"taxonomy":"product_tag","embeddable":true,"href":"https:\/\/staging.telescoop.nl\/en\/wp-json\/wp\/v2\/product_tag?post=34079"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}