{"product_id":"farpoint-clear-bahtinov-focus-mask-150mm-square","title":"Farpoint Clear Bahtinov Focus Mask — 150mm Square","description":"\u003c!--FPSEO|v1|20260518|111111111110000010--\u003e\n\u003cp\u003e\u003cstrong\u003eClear Bahtinov focus mask, 150mm square — fits 150mm filter holder systems.\u003c\/strong\u003e The clear construction lets more light reach your sensor for brighter star images and stronger, more visible diffraction lines. Slides into the holder slot, gives you perfect focus in seconds, and slides out cleanly when you're done. Made in our own shop in the USA — American materials, American machinery, by Americans.\u003c\/p\u003e\n\n\u003cp\u003e\u003cem\u003eWorks with most 150mm filter holder systems — Lee, NiSi, Cokin XL, Haida, Wine Country Camera, and others. Holder and lens-specific adapter ring sold separately.\u003c\/em\u003e\u003c\/p\u003e\n\n\u003ch2\u003eWhy a Farpoint Clear Bahtinov\u003c\/h2\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eClear construction for brighter focus images.\u003c\/strong\u003e Instead of opaque material, the Clear Bahtinov uses a transparent base that lets more light reach your sensor — producing brighter star images with stronger, more visible diffraction lines for easier focus reads.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eDrops into a 150mm holder slot.\u003c\/strong\u003e Slides cleanly into the filter slot — focus check, slide out, shoot. Same workflow as any 150mm filter swap.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eMade in the USA.\u003c\/strong\u003e Designed and manufactured in our own shop with American materials, American machinery, and American workmanship.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e15+ year track record.\u003c\/strong\u003e Farpoint has been making focus masks longer than nearly anyone in the hobby.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eWhat's in the box\u003c\/h2\u003e\n\u003cul\u003e\n  \u003cli\u003e1× Farpoint Clear Bahtinov Focus Mask, 150mm square\u003c\/li\u003e\n  \u003cli\u003eInstructions for use\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eWhat you'll need\u003c\/h2\u003e\n\u003cp\u003eA 150mm filter holder system (Lee, NiSi, Cokin XL, Haida, Wine Country Camera, or similar) mounted on your camera lens via the appropriate lens-specific adapter ring. Both are sold separately at any photography retailer. Once your holder is set up, the Clear Bahtinov slides into the filter slot just like any other 150mm filter.\u003c\/p\u003e\n\n\u003ch2\u003eHow a Bahtinov mask works\u003c\/h2\u003e\n\u003cp\u003eSlide the mask into your 150mm filter holder and aim at a fairly bright star. Take a short exposure. You'll see three diffraction spikes — two angled spikes forming an X, plus a third central spike that's offset to one side or the other when the lens is out of focus. The clear construction lets the diffraction lines show up more strongly than an opaque mask. As you adjust the focus ring, the central spike moves across the X. When it lands perfectly centered and symmetrical, you've hit optimum focus. Slide the mask out and start shooting.\u003c\/p\u003e\n\n\u003cp style=\"text-align: center;\"\u003e\n  \u003ciframe title=\"YouTube video player\" src=\"https:\/\/www.youtube.com\/embed\/bqtRWj1kLgQ\" height=\"315\" width=\"560\" style=\"max-width: 100%;\"\u003e\u003c\/iframe\u003e\n\u003c\/p\u003e\n\n\u003cp style=\"text-align: center;\"\u003e\n  \u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0567\/6639\/8617\/files\/bmaskanimation.gif?v=1778193011\" alt=\"Animated GIF showing a star coming into focus through a Bahtinov mask\" width=\"256\" height=\"256\" style=\"display: block; margin: 0 auto;\"\u003e\n  \u003cbr\u003e\u003cem\u003eA star coming into focus through a Bahtinov mask\u003c\/em\u003e\n\u003c\/p\u003e\n\n\u003ch2\u003eFree software for precise focus measurement\u003c\/h2\u003e\n\u003cp\u003eIf you want machine-precise focus instead of eyeballing the spike pattern, free open-source software can analyze the diffraction image automatically:\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eBahtinov-Collimator\u003c\/strong\u003e — a Windows tool that quantifies focus error directly from your image. \u003ca href=\"https:\/\/github.com\/insertnamehere1\/Bahtinov-Collimator\" rel=\"noopener\" target=\"_blank\"\u003eAvailable on GitHub\u003c\/a\u003e.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eAPT (Astro Photography Tool)\u003c\/strong\u003e — Bahtinov mask analysis is built into APT's image-capture workflow.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp style=\"text-align: center;\"\u003e\n  \u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0567\/6639\/8617\/files\/Collimation.jpg?v=1737820356\" alt=\"Screenshot of Bahtinov-Collimator software analyzing a star image\" width=\"551\" height=\"408\" style=\"display: block; margin: 0 auto; max-width: 100%; height: auto;\"\u003e\n  \u003cbr\u003e\u003cem\u003eBahtinov-Collimator analyzing a star image for precise focus measurement\u003c\/em\u003e\n\u003c\/p\u003e\n\n\u003ch2\u003eNeed a different size?\u003c\/h2\u003e\n\u003cp\u003eThe Clear Bahtinov is also available in 85mm (fits Cokin P holders) and 100mm (fits Cokin Z holders) sizes. We also make opaque ABS Bahtinov masks for Cokin P\/Z holders and round filter threads from 52mm up to 82mm. \u003ca href=\"\/collections\/dslr-camera-focus-masks-focus-masks-telescope-accessories\"\u003eSee all DSLR lens Bahtinov masks →\u003c\/a\u003e\u003c\/p\u003e\n\n\u003ch2\u003eRelated guides\u003c\/h2\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003ca href=\"\/pages\/focus-masks\"\u003eFocus Masks Buyer's Guide\u003c\/a\u003e — material comparison, custom-fit vs adjustable, choosing the right type\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp style=\"text-align: center;\"\u003e\n  \u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0567\/6639\/8617\/files\/DiffSpike.jpg?v=1737826264\" alt=\"Diffraction spike pattern at perfect focus through a Bahtinov mask\" style=\"display: block; margin: 0 auto; max-width: 100%; height: auto;\"\u003e\n  \u003cbr\u003e\u003cem\u003eThe unmistakable diffraction spike pattern at perfect focus\u003c\/em\u003e\n\u003c\/p\u003e","brand":"Farpoint","offers":[{"title":"Default Title","offer_id":40630667706521,"sku":"FPC479","price":44.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0567\/6639\/8617\/products\/FPC479onbrown.jpg?v=1775145695","url":"https:\/\/farpointastro.com\/products\/farpoint-clear-bahtinov-focus-mask-150mm-square","provider":"FarpointAstro","version":"1.0","type":"link"}