{"product_id":"rb-focus-aperture-ring-for-newtonian-telescopes","title":"RB Focus Aperture Ring for Newtonian Telescopes","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003eDesigned for 150 mm, 200 mm, and 250 mm Newtonians\u003c\/li\u003e\n\u003cli\u003eRemoves the helix-shaped reflections caused by mirror clips\u003c\/li\u003e\n\u003cli\u003eMasks Primary Mirror Retaining Clips\u003c\/li\u003e\n\u003cli\u003eSimple Installation\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c!-- more --\u003e\n\u003cul class=\"tabs\"\u003e\n\u003cli class=\"active\"\u003eDescription\u003c\/li\u003e\n\u003cli\u003eFAQ\u003c\/li\u003e\n\u003cli\u003eSpecifications\u003c\/li\u003e\n\u003cli\u003eIn the Box\u003c\/li\u003e\n\u003cli\u003eWarranty\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cul class=\"tabs-content\"\u003e\n\u003cli class=\"active\"\u003e\n\u003cdiv\u003e\n  \u003cdiv class=\"DAV-bg-light\"\u003e\n    \u003cdiv class=\"DAV-section-center\"\u003e\n      \u003ch2\u003eRB Focus Aperture Ring for Newtonian Telescopes\u003c\/h2\u003e\n      \u003cp\u003eThe RB Focus Aperture Ring for Newtonian Telescopes is made for 150 mm, 200 mm and 250 mm reflectors. It covers the clips that hold the primary mirror in its cell, which RB Focus identifies as the cause of the helix-shaped reflections that appear around stars in addition to the diffraction spikes.\u003c\/p\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv class=\"DAV-bg-light\"\u003e\n    \u003cdiv class=\"DAV-section\"\u003e\n      \u003ch3\u003eClean Diffraction Patterns on 150, 200, and 250 mm Newtonians\u003c\/h3\u003e\n      \u003cp\u003eIf you have seen helix-shaped reflections around stars, separate from the diffraction spikes, RB Focus explains that they come from the clips that hold the mirror to its cell.\u003c\/p\u003e\n      \u003cp\u003eThe aperture ring covers the clips and, as RB Focus states, solves the problem completely. RB Focus describes it as very simple to install.\u003c\/p\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n  \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eWhat causes the extra reflections the RB Focus Aperture Ring fixes?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eThe strange, helix-shaped reflections are caused by the small metal clips that hold the primary mirror in its cell. These clips protrude slightly into the telescope's light path, creating their own unique diffraction artifacts. The \u003cstrong\u003eRB Focus Aperture Ring\u003c\/strong\u003e masks these clips, eliminating the unwanted reflections and leaving only the clean diffraction spikes from the secondary mirror's spider vanes.\u003c\/p\u003e\n  \u003c\/div\u003e\n    \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eHow do I install the RB Focus Aperture Ring?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eRB Focus describes it as very simple to install: the ring covers the primary mirror clips. RB Focus gives no further installation details.\u003c\/p\u003e\n\u003c\/div\u003e\n                \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eDo I need a specific RB Focus Aperture Ring for my telescope's aperture?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes. Choose the size that matches your telescope's aperture: 150 mm, 200 mm or 250 mm.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n    \u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003ePurpose\u003c\/td\u003e\n\u003ctd\u003eCovers the primary mirror clips\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSizes\u003c\/td\u003e\n\u003ctd\u003eFor 150, 200 and 250 mm aperture reflectors\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n  \u003c\/table\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eAperture ring\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003cli\u003e\u003ca href=\"https:\/\/davidastro.com\/pages\/rb-focus-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eRB Focus 2-Year Warranty\u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"RB Focus","offers":[{"title":"150 mm","offer_id":67881972072733,"sku":"RB-APRING-150","price":41.0,"currency_code":"CAD","in_stock":true},{"title":"200 mm","offer_id":67881972105501,"sku":"RB-APRING-200","price":41.0,"currency_code":"CAD","in_stock":true},{"title":"250 mm","offer_id":67881972138269,"sku":"RB-APRING-250","price":58.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/78d234_96012f5e51c148ae9bf9f520f3853a8e_mv2.jpg?v=1793070918","url":"https:\/\/davidastro.com\/fr\/products\/rb-focus-aperture-ring-for-newtonian-telescopes","provider":"David Astro","version":"1.0","type":"link"}