{"title":"William Optics Focus Masks","description":"\u003cp\u003eWilliam Optics Bahtinov focusing masks, sized by dew shield diameter from 75mm up to 308mm, plus the patented mask cover for the Takahashi FSQ-106. A Bahtinov mask clips over the front of the telescope and turns a bright star into a diffraction pattern — centre the middle spike and you are in focus.\u003c\/p\u003e\u003cp\u003eGoods ship factory-sealed. Measure the outside diameter of your dew shield before ordering, or tell us your telescope and we'll confirm the size.\u003c\/p\u003e","products":[{"product_id":"diffraction-spikes-bahtinov-focusing-mask-for-telescopes-dew-shield-diameter-from-105mm-148mm","title":"Diffraction Spikes Bahtinov Focusing Mask for Telescopes Dew Shield Diameter From 105mm -148mm","description":"\u003cspan style=\"margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(51, 51, 51); font-family: \" open sans neue helvetica arial sans-serif rgb background-color:=\"\"\u003eThe new Optical acrylic sheet offers 92% of light transmission that gave you the highest and brightest diffraction Spikes for Focusing !\u003c\/span\u003e\u003cbr style=\"margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(51, 51, 51); font-family: \" open sans neue helvetica arial sans-serif rgb font-size:=\"\" background-color:=\"\"\u003e\u003cspan style=\"margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(51, 51, 51); font-family: \" open sans neue helvetica arial sans-serif rgb background-color:=\"\"\u003eIt’s about 3 times brighter than traditional metal type.\u003c\/span\u003e","brand":"William Optics","offers":[{"title":"Default Title","offer_id":44013398786159,"sku":"BM-DS-GR55","price":94.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/img_1187__23933.png?v=1766552983"},{"product_id":"diffraction-spikes-bahtinov-focusing-mask-for-telescopes-dew-shield-diameter-from-75mm-110mm","title":"Diffraction Spikes Bahtinov Focusing Mask for Telescopes Dew Shield Diameter From 75mm -110mm","description":"\u003cspan style=\"margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(51, 51, 51); font-family: \" open sans neue helvetica arial sans-serif rgb background-color:=\"\"\u003eThe new Optical acrylic sheet offers 92% of light transmission that gave you the highest and brightest diffraction Spikes for Focusing !\u003c\/span\u003e\u003cbr style=\"margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(51, 51, 51); font-family: \" open sans neue helvetica arial sans-serif rgb font-size:=\"\" background-color:=\"\"\u003e\u003cspan style=\"margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(51, 51, 51); font-family: \" open sans neue helvetica arial sans-serif rgb background-color:=\"\"\u003eIt’s about 3 times brighter than traditional metal type.\u003c\/span\u003e   \u003cdiv\u003e\u003cspan style=\"margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(51, 51, 51); font-family: \" open sans neue helvetica arial sans-serif background-color: rgb\u003e\u003cbr\u003e\u003c\/span\u003e\u003c\/div\u003e\u003cdiv\u003e\u003cspan style=\"margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(51, 51, 51); font-family: \" open sans neue helvetica arial sans-serif background-color: rgb\u003eFor dewshields 75 - 110mm in diameter\u003c\/span\u003e\u003c\/div\u003e","brand":"William Optics","offers":[{"title":"Default Title","offer_id":44013399277679,"sku":"BM-DS-GR45","price":81.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/img_1450__03447.png?v=1766553068"},{"product_id":"diffraction-spikes-bahtinov-focusing-mask-for-telescopes-dew-shield-diameter-from-172mm-235mm","title":"Diffraction Spikes Bahtinov Focusing Mask for Telescopes Dew Shield Diameter From 172mm -235mm","description":"\u003cspan style=\"margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(51, 51, 51); font-family: \" open sans neue helvetica arial sans-serif rgb background-color:=\"\"\u003eThe new Optical acrylic sheet offers 92% of light transmission that gave you the highest and brightest diffraction Spikes for Focusing !\u003c\/span\u003e\u003cbr style=\"margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(51, 51, 51); font-family: \" open sans neue helvetica arial sans-serif rgb font-size:=\"\" background-color:=\"\"\u003e\u003cspan style=\"margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(51, 51, 51); font-family: \" open sans neue helvetica arial sans-serif rgb background-color:=\"\"\u003eIt’s about 3 times brighter than traditional metal type.\u003c\/span\u003e   \u003cdiv\u003e\u003cspan style=\"margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(51, 51, 51); font-family: \" open sans neue helvetica arial sans-serif background-color: rgb\u003e\u003cbr\u003e\u003c\/span\u003e\u003c\/div\u003e\u003cdiv\u003e\u003cspan style=\"margin: 0px; padding: 0px; box-sizing: border-box; color: rgb(51, 51, 51); font-family: \" open sans neue helvetica arial sans-serif background-color: rgb\u003eFor dewshields 172mm -235mm\u003c\/span\u003e\u003c\/div\u003e","brand":"William Optics","offers":[{"title":"Default Title","offer_id":44013399310447,"sku":"BM-DS-GR90","price":121.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/img_1448__51554.png?v=1766553076"},{"product_id":"bahtinov-mask-cover-patented-for-takahashi-fsq106-telescopes","title":"Bahtinov Mask Cover (Patented) for Takahashi FSQ106 Telescopes","description":"\u003cp style=\"margin: 0px 0px 1rem; padding: 0px; color: rgb(51, 51, 51); font-family: Roboto, Arial, \" helvetica neue sans-serif rgb font-size:=\"\" background-color:=\"\"\u003eNew Innovative Bahtinov Mask Cover (Patented) for Takahashi FSQ106 Telescopes\u003c\/p\u003e\u003cimg src=\"https:\/\/williamoptics.com\/pub\/media\/wysiwyg\/Product\/CPBM-TH106\/IMG_9113.png\" alt=\"\" style=\"margin: 0px; padding: 0px; border: 0px; height: auto; max-width: 100%; vertical-align: top; color: rgb(51, 51, 51); font-family: Roboto, Arial, \" helvetica neue sans-serif rgb font-size:=\"\" background-color:=\"\"\u003e","brand":"William Optics","offers":[{"title":"Default Title","offer_id":44013465960559,"sku":"CPBM-TH106-BL","price":219.99,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/img_1907__12321.png?v=1766553784"},{"product_id":"bahtinov-focusing-mask-from-243mm-308mm","title":"Bahtinov Focusing Mask From 243mm -308mm","description":"\u003cspan style=\"font-family: Arial;\"\u003eDiffraction Spikes Bahtinov Focusing Mask for Telescopes Dew Shield Diameter From 243mm -308mm\u003c\/span\u003e","brand":"William Optics","offers":[{"title":"Default Title","offer_id":44013508329583,"sku":"BM-DS-GR150","price":149.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/img_2544__82944.png?v=1766554520"}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/collections\/api1bqiz3__09347.jpg?v=1767588175","url":"https:\/\/ontariotelescope.com\/collections\/william-optics-focus-masks.oembed","provider":"Ontario Telescope and Accessories","version":"1.0","type":"link"}