{"title":"Starfield Focus Masks","description":"\u003cp\u003eStarfield Bahtinov focusing masks in 80mm through 250mm, plus a dedicated mask for the Celestron C11. Drop one over the aperture, focus on a bright star until the centre spike is centred, then lift it off and shoot.\u003c\/p\u003e\u003cp\u003eGoods ship factory-sealed. Sizes are by tube outside diameter — tell us your telescope and we'll confirm which one fits.\u003c\/p\u003e","products":[{"product_id":"starfield-80-mm-focus-mask","title":"Starfield 80 mm Focus Mask","description":"\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003eThe \u003cspan class=\"x-el x-el-span c2-6p c2-6q c2-ab c2-j c2-2i c2-ac c2-3 x-d-ux\" style=\"box-sizing: inherit; font-weight: 700; letter-spacing: inherit; text-transform: inherit; line-height: inherit; font-size: inherit !important;\"\u003eBahtinov mask\u003c\/span\u003e is used focus small telescopes accurately. Although \u003cspan class=\"x-el x-el-span c2-6p c2-6q c2-ab c2-j c2-2i c2-ac c2-3 x-d-ux\" style=\"box-sizing: inherit; font-weight: 700; letter-spacing: inherit; text-transform: inherit; line-height: inherit; font-size: inherit !important;\"\u003emasks\u003c\/span\u003e have long been used as focusing aids, the distinctive pattern was invented by Russian amateur astrophotographer Pavel \u003cspan class=\"x-el x-el-span c2-6p c2-6q c2-ab c2-j c2-2i c2-ac c2-3 x-d-ux\" style=\"box-sizing: inherit; font-weight: 700; letter-spacing: inherit; text-transform: inherit; line-height: inherit; font-size: inherit !important;\"\u003eBahtinov.   \u003c\/span\u003e\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003e\u003cbr style=\"box-sizing: inherit; clear: both;\"\u003e\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003eSimply place the mast in front of the main optic of your telescope and take a picture.  Look at the diffraction spike pattern and continue until the spikes are even.   Using a Bahtinov mask is the easiest way to get into focus.\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003e\u003cbr\u003e\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003eThis 80mm mask is great for small scopes.\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003e\u003cbr\u003e\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003e\u003cspan style=\"font-weight: 700;\"\u003eFits dew shields with an outside diameter of 87-105mm\u003c\/span\u003e\u003c\/span\u003e\u003c\/p\u003e","brand":"Starfield","offers":[{"title":"Default Title","offer_id":44013582811247,"sku":"FM-80","price":28.99,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/focus_252520mask__16402.1682640526.1280.1280.jpg?v=1766556946"},{"product_id":"starfield-100-mm-focus-mask","title":"Starfield 100 mm Focus Mask","description":"\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003eThe \u003cspan class=\"x-el x-el-span c2-6p c2-6q c2-ab c2-j c2-2i c2-ac c2-3 x-d-ux\" style=\"box-sizing: inherit; font-weight: 700; letter-spacing: inherit; text-transform: inherit; line-height: inherit; font-size: inherit !important;\"\u003eBahtinov mask\u003c\/span\u003e is used focus small telescopes accurately. Although \u003cspan class=\"x-el x-el-span c2-6p c2-6q c2-ab c2-j c2-2i c2-ac c2-3 x-d-ux\" style=\"box-sizing: inherit; font-weight: 700; letter-spacing: inherit; text-transform: inherit; line-height: inherit; font-size: inherit !important;\"\u003emasks\u003c\/span\u003e have long been used as focusing aids, the distinctive pattern was invented by Russian amateur astrophotographer Pavel \u003cspan class=\"x-el x-el-span c2-6p c2-6q c2-ab c2-j c2-2i c2-ac c2-3 x-d-ux\" style=\"box-sizing: inherit; font-weight: 700; letter-spacing: inherit; text-transform: inherit; line-height: inherit; font-size: inherit !important;\"\u003eBahtinov.   \u003c\/span\u003e\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003e\u003cbr style=\"box-sizing: inherit; clear: both;\"\u003e\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003eSimply place the mast in front of the main optic of your telescope and take a picture.  Look at the diffraction spike pattern and continue until the spikes are even.   Using a Bahtinov mask is the easiest way to get into focus.\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003e\u003cbr\u003e\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003eThis 100mm mask is great for 90 - 105mm class telescopes.\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003e\u003cbr\u003e\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003e\u003cspan style=\"font-weight: 700;\"\u003eFits dew shields with an outside diameter of 109-145mm\u003c\/span\u003e\u003c\/span\u003e\u003c\/p\u003e","brand":"Starfield","offers":[{"title":"Default Title","offer_id":44013582942319,"sku":"FM-100","price":29.99,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/focus_252520mask__12688.1682640527.1280.1280.jpg?v=1766556951"},{"product_id":"starfield-120-mm-focus-mask","title":"Starfield 120 mm Focus Mask","description":"\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003eThe \u003cspan class=\"x-el x-el-span c2-6p c2-6q c2-ab c2-j c2-2i c2-ac c2-3 x-d-ux\" style=\"box-sizing: inherit; font-weight: 700; letter-spacing: inherit; text-transform: inherit; line-height: inherit; font-size: inherit !important;\"\u003eBahtinov mask\u003c\/span\u003e is used focus small telescopes accurately. Although \u003cspan class=\"x-el x-el-span c2-6p c2-6q c2-ab c2-j c2-2i c2-ac c2-3 x-d-ux\" style=\"box-sizing: inherit; font-weight: 700; letter-spacing: inherit; text-transform: inherit; line-height: inherit; font-size: inherit !important;\"\u003emasks\u003c\/span\u003e have long been used as focusing aids, the distinctive pattern was invented by Russian amateur astrophotographer Pavel \u003cspan class=\"x-el x-el-span c2-6p c2-6q c2-ab c2-j c2-2i c2-ac c2-3 x-d-ux\" style=\"box-sizing: inherit; font-weight: 700; letter-spacing: inherit; text-transform: inherit; line-height: inherit; font-size: inherit !important;\"\u003eBahtinov.   \u003c\/span\u003e\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003e\u003cbr style=\"box-sizing: inherit; clear: both;\"\u003e\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003eSimply place the mast in front of the main optic of your telescope and take a picture.  Look at the diffraction spike pattern and continue until the spikes are even.   Using a Bahtinov mask is the easiest way to get into focus.\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003e\u003cbr\u003e\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003eThis 120mm mask is great for 105 - 125mm class telescopes,\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003e\u003cbr\u003e\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003e\u003cspan style=\"font-weight: 700;\"\u003eFits dew shields with an outside diameter of 120-152mm\u003c\/span\u003e\u003c\/span\u003e\u003c\/p\u003e","brand":"Starfield","offers":[{"title":"Default Title","offer_id":44013583073391,"sku":"FM-120","price":34.99,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/focus_252520mask__82659.1682640527.1280.1280.jpg?v=1766556956"},{"product_id":"starfield-140-mm-focus-mask","title":"Starfield 140 mm Focus Mask","description":"\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003eThe \u003cspan class=\"x-el x-el-span c2-6p c2-6q c2-ab c2-j c2-2i c2-ac c2-3 x-d-ux\" style=\"box-sizing: inherit; font-weight: 700; letter-spacing: inherit; text-transform: inherit; line-height: inherit; font-size: inherit !important;\"\u003eBahtinov mask\u003c\/span\u003e is used focus small telescopes accurately. Although \u003cspan class=\"x-el x-el-span c2-6p c2-6q c2-ab c2-j c2-2i c2-ac c2-3 x-d-ux\" style=\"box-sizing: inherit; font-weight: 700; letter-spacing: inherit; text-transform: inherit; line-height: inherit; font-size: inherit !important;\"\u003emasks\u003c\/span\u003e have long been used as focusing aids, the distinctive pattern was invented by Russian amateur astrophotographer Pavel \u003cspan class=\"x-el x-el-span c2-6p c2-6q c2-ab c2-j c2-2i c2-ac c2-3 x-d-ux\" style=\"box-sizing: inherit; font-weight: 700; letter-spacing: inherit; text-transform: inherit; line-height: inherit; font-size: inherit !important;\"\u003eBahtinov.   \u003c\/span\u003e\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003e\u003cbr style=\"box-sizing: inherit; clear: both;\"\u003e\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003eSimply place the mast in front of the main optic of your telescope and take a picture.  Look at the diffraction spike pattern and continue until the spikes are even.   Using a Bahtinov mask is the easiest way to get into focus.\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003e\u003cbr\u003e\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003eThis 140mm mask is great for 125mm - 130mm class telescopes\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003e\u003cbr\u003e\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003e\u003cspan style=\"font-weight: 700;\"\u003eFits dew shields with an outside diameter of 153-192mm\u003c\/span\u003e\u003c\/span\u003e\u003c\/p\u003e","brand":"Starfield","offers":[{"title":"Default Title","offer_id":44013583171695,"sku":"FM-140","price":46.99,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/focus_252520mask__00503.1682640528.1280.1280.jpg?v=1766556963"},{"product_id":"starfield-160-mm-focus-mask","title":"Starfield 160 mm Focus Mask","description":"\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003eThe \u003cspan class=\"x-el x-el-span c2-6p c2-6q c2-ab c2-j c2-2i c2-ac c2-3 x-d-ux\" style=\"box-sizing: inherit; font-weight: 700; letter-spacing: inherit; text-transform: inherit; line-height: inherit; font-size: inherit !important;\"\u003eBahtinov mask\u003c\/span\u003e is used focus small telescopes accurately. Although \u003cspan class=\"x-el x-el-span c2-6p c2-6q c2-ab c2-j c2-2i c2-ac c2-3 x-d-ux\" style=\"box-sizing: inherit; font-weight: 700; letter-spacing: inherit; text-transform: inherit; line-height: inherit; font-size: inherit !important;\"\u003emasks\u003c\/span\u003e have long been used as focusing aids, the distinctive pattern was invented by Russian amateur astrophotographer Pavel \u003cspan class=\"x-el x-el-span c2-6p c2-6q c2-ab c2-j c2-2i c2-ac c2-3 x-d-ux\" style=\"box-sizing: inherit; font-weight: 700; letter-spacing: inherit; text-transform: inherit; line-height: inherit; font-size: inherit !important;\"\u003eBahtinov.   \u003c\/span\u003e\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003e\u003cbr style=\"box-sizing: inherit; clear: both;\"\u003e\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003eSimply place the mast in front of the main optic of your telescope and take a picture.  Look at the diffraction spike pattern and continue until the spikes are even.   Using a Bahtinov mask is the easiest way to get into focus.\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003e\u003cbr\u003e\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003eThis 160mm mask is great for 140 - 150mm class telescopes\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003e\u003cbr\u003e\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003e\u003cspan style=\"font-weight: 700;\"\u003eFits dew shields with an outside diameter of 175-212mm\u003c\/span\u003e\u003c\/span\u003e\u003c\/p\u003e","brand":"Starfield","offers":[{"title":"Default Title","offer_id":44013583302767,"sku":"FM-160","price":49.99,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/focus_252520mask__17837.1682640528.1280.1280.jpg?v=1766556966"},{"product_id":"starfield-180-mm-focus-mask","title":"Starfield 180 mm Focus Mask","description":"\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003eThe \u003cspan class=\"x-el x-el-span c2-6p c2-6q c2-ab c2-j c2-2i c2-ac c2-3 x-d-ux\" style=\"box-sizing: inherit; font-weight: 700; letter-spacing: inherit; text-transform: inherit; line-height: inherit; font-size: inherit !important;\"\u003eBahtinov mask\u003c\/span\u003e is used focus small telescopes accurately. Although \u003cspan class=\"x-el x-el-span c2-6p c2-6q c2-ab c2-j c2-2i c2-ac c2-3 x-d-ux\" style=\"box-sizing: inherit; font-weight: 700; letter-spacing: inherit; text-transform: inherit; line-height: inherit; font-size: inherit !important;\"\u003emasks\u003c\/span\u003e have long been used as focusing aids, the distinctive pattern was invented by Russian amateur astrophotographer Pavel \u003cspan class=\"x-el x-el-span c2-6p c2-6q c2-ab c2-j c2-2i c2-ac c2-3 x-d-ux\" style=\"box-sizing: inherit; font-weight: 700; letter-spacing: inherit; text-transform: inherit; line-height: inherit; font-size: inherit !important;\"\u003eBahtinov.   \u003c\/span\u003e\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003e\u003cbr style=\"box-sizing: inherit; clear: both;\"\u003e\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003eSimply place the mast in front of the main optic of your telescope and take a picture.  Look at the diffraction spike pattern and continue until the spikes are even.   Using a Bahtinov mask is the easiest way to get into focus.\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003e\u003cbr\u003e\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003eThis 180mm mask is great for 150 - 165mm class telescopes\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003e\u003cbr\u003e\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003e\u003cspan style=\"font-weight: 700;\"\u003eFits dew shields with an outside diameter of 185-210mm\u003c\/span\u003e\u003c\/span\u003e\u003c\/p\u003e","brand":"Starfield","offers":[{"title":"Default Title","offer_id":44013583335535,"sku":"FM-180","price":54.99,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/focus_252520mask__06806.1682640529.1280.1280.jpg?v=1766556971"},{"product_id":"starfield-200-mm-focus-mask","title":"Starfield 200 mm Focus Mask","description":"\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003eThe \u003cspan class=\"x-el x-el-span c2-6p c2-6q c2-ab c2-j c2-2i c2-ac c2-3 x-d-ux\" style=\"box-sizing: inherit; font-weight: 700; letter-spacing: inherit; text-transform: inherit; line-height: inherit; font-size: inherit !important;\"\u003eBahtinov mask\u003c\/span\u003e is used focus small telescopes accurately. Although \u003cspan class=\"x-el x-el-span c2-6p c2-6q c2-ab c2-j c2-2i c2-ac c2-3 x-d-ux\" style=\"box-sizing: inherit; font-weight: 700; letter-spacing: inherit; text-transform: inherit; line-height: inherit; font-size: inherit !important;\"\u003emasks\u003c\/span\u003e have long been used as focusing aids, the distinctive pattern was invented by Russian amateur astrophotographer Pavel \u003cspan class=\"x-el x-el-span c2-6p c2-6q c2-ab c2-j c2-2i c2-ac c2-3 x-d-ux\" style=\"box-sizing: inherit; font-weight: 700; letter-spacing: inherit; text-transform: inherit; line-height: inherit; font-size: inherit !important;\"\u003eBahtinov.   \u003c\/span\u003e\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003e\u003cbr style=\"box-sizing: inherit; clear: both;\"\u003e\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003eSimply place the mast in front of the main optic of your telescope and take a picture.  Look at the diffraction spike pattern and continue until the spikes are even.   Using a Bahtinov mask is the easiest way to get into focus.\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003e\u003cbr\u003e\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003eThis 200mm mask is great 8\" SCT or RC telescopes\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003e\u003cbr\u003e\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003e\u003cspan style=\"font-weight: 700;\"\u003eFits dew shields with an outside diameter of 212-252mm\u003c\/span\u003e\u003c\/span\u003e\u003c\/p\u003e","brand":"Starfield","offers":[{"title":"Default Title","offer_id":44013583466607,"sku":"FM-200","price":64.99,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/focus_252520mask__69116.1682635521.1280.1280.jpg?v=1766556976"},{"product_id":"starfield-250mm-focus-mask","title":"Starfield 250mm Focus Mask","description":"\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003eThe \u003cspan class=\"x-el x-el-span c2-6p c2-6q c2-ab c2-j c2-2i c2-ac c2-3 x-d-ux\" style=\"box-sizing: inherit; font-weight: 700; letter-spacing: inherit; text-transform: inherit; line-height: inherit; font-size: inherit !important;\"\u003eBahtinov mask\u003c\/span\u003e is used focus small telescopes accurately. Although \u003cspan class=\"x-el x-el-span c2-6p c2-6q c2-ab c2-j c2-2i c2-ac c2-3 x-d-ux\" style=\"box-sizing: inherit; font-weight: 700; letter-spacing: inherit; text-transform: inherit; line-height: inherit; font-size: inherit !important;\"\u003emasks\u003c\/span\u003e have long been used as focusing aids, the distinctive pattern was invented by Russian amateur astrophotographer Pavel \u003cspan class=\"x-el x-el-span c2-6p c2-6q c2-ab c2-j c2-2i c2-ac c2-3 x-d-ux\" style=\"box-sizing: inherit; font-weight: 700; letter-spacing: inherit; text-transform: inherit; line-height: inherit; font-size: inherit !important;\"\u003eBahtinov.   \u003c\/span\u003e\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003e\u003cbr style=\"box-sizing: inherit; clear: both;\"\u003e\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003eSimply place the mast in front of the main optic of your telescope and take a picture.  Look at the diffraction spike pattern and continue until the spikes are even.   Using a Bahtinov mask is the easiest way to get into focus.\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003e\u003cbr\u003e\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003eThis 250mm mask is great 10\" SCT or RC telescopes\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003e\u003cbr\u003e\u003c\/span\u003e\u003c\/p\u003e\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);\"\u003e\u003cbr\u003e\u003c\/p\u003e","brand":"Starfield","offers":[{"title":"Default Title","offer_id":44013699563631,"sku":"FM-250","price":65.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/focus_252520mask__87121.1682640838.1280.1280.jpg?v=1766560154"},{"product_id":"starfield-c11-focus-mask","title":"Starfield C11 Focus Mask","description":"\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: #ffffff;\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003eThe \u003cspan class=\"x-el x-el-span c2-6p c2-6q c2-ab c2-j c2-2i c2-ac c2-3 x-d-ux\" style=\"box-sizing: inherit; font-weight: bold; letter-spacing: inherit; text-transform: inherit; line-height: inherit; font-size: inherit !important;\"\u003eBahtinov mask\u003c\/span\u003e is used focus small telescopes accurately. Although \u003cspan class=\"x-el x-el-span c2-6p c2-6q c2-ab c2-j c2-2i c2-ac c2-3 x-d-ux\" style=\"box-sizing: inherit; font-weight: bold; letter-spacing: inherit; text-transform: inherit; line-height: inherit; font-size: inherit !important;\"\u003emasks\u003c\/span\u003e have long been used as focusing aids, the distinctive pattern was invented by Russian amateur astrophotographer Pavel \u003cspan class=\"x-el x-el-span c2-6p c2-6q c2-ab c2-j c2-2i c2-ac c2-3 x-d-ux\" style=\"box-sizing: inherit; font-weight: bold; letter-spacing: inherit; text-transform: inherit; line-height: inherit; font-size: inherit !important;\"\u003eBahtinov. \u003c\/span\u003e\u003c\/span\u003e\u003c\/p\u003e\n\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: #ffffff;\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003e \u003c\/span\u003e\u003c\/p\u003e\n\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: #ffffff;\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003eSimply place the mast in front of the main optic of your telescope and take a picture. Look at the diffraction spike pattern and continue until the spikes are even. Using a Bahtinov mask is the easiest way to get into focus.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: #ffffff;\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003e \u003c\/span\u003e\u003c\/p\u003e\n\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: #ffffff;\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003eThis mask is meant to fit a C11SCT or EdgeHD\u003c\/span\u003e\u003c\/p\u003e\n\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: #ffffff;\"\u003e\u003cspan style=\"box-sizing: inherit;\"\u003e \u003c\/span\u003e\u003c\/p\u003e\n\u003cp style=\"box-sizing: inherit; margin: 0px; font-family: Helvetica, arial, sans-serif; font-size: 16px; background-color: #ffffff;\"\u003e \u003c\/p\u003e","brand":"Starfield","offers":[{"title":"Default Title","offer_id":44014073610351,"sku":"FM-C11","price":79.99,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/focus_2525252520mask__87121.1682640838.1280.1280__37720.1707938398.1280.1280.jpg?v=1766569577"}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/collections\/apiuxlytu__49594.jpg?v=1767588172","url":"https:\/\/ontariotelescope.com\/collections\/starfield-focus-masks.oembed","provider":"Ontario Telescope and Accessories","version":"1.0","type":"link"}