{"product_id":"artesky-filtro-erf-130mm-con-cella-in-metallo-o178mm","title":"Artesky ERF Filter 130mm with Metal Cell Ø178mm","description":"\u003cp\u003e\u003cstrong\u003eThe Artesky ERF 130mm filter\u003c\/strong\u003e is an infrared pre-filter \u003cstrong\u003ealready mounted in an aluminum cell\u003c\/strong\u003e (Ø178mm), ready to use in front of the telescope objective: essential for H-alpha solar observation with Daystar or Solar Spectrum filters.\u003c\/p\u003e\n\n\u003ch2\u003eWhat the ERF is for\u003c\/h2\u003e\n\u003cp\u003eAn ERF (Energy Rejection Filter) reflects most of the solar energy before it enters the optical tube, preventing overheating of the H-alpha etalon and the telescope optics. Unlike bare glass, the Artesky version with cell is ready to mount, with no need for 3D-printed or custom cells.\u003c\/p\u003e\n\n\u003ch2\u003eHomogeneous high-transparency glass\u003c\/h2\u003e\n\u003cp\u003eThe glass substrate is not the traditional coloured absorptive type, but highly transparent and homogeneous, polished to objective-lens quality, with a high-performance reflective coating on one side.\u003c\/p\u003e\n\n\u003ch2\u003eExclusive dielectric coating\u003c\/h2\u003e\n\u003cp\u003eThe Artesky coating reflects the unwanted spectrum from 200 to 1100nm, letting through only a 60nm window centred on H-alpha (656.28nm), with 95% peak transmittance and OD4 blocking depth.\u003c\/p\u003e\n\n\u003ch2\u003eTechnical specifications\u003c\/h2\u003e\n\u003ctable\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\u003ctd\u003eGlass diameter\u003c\/td\u003e\u003ctd\u003e130 mm\u003c\/td\u003e\u003c\/tr\u003e\n\u003ctr\u003e\u003ctd\u003eGlass thickness\u003c\/td\u003e\u003ctd\u003e12 mm\u003c\/td\u003e\u003c\/tr\u003e\n\u003ctr\u003e\u003ctd\u003eSurface flatness\u003c\/td\u003e\u003ctd\u003eλ\/4\u003c\/td\u003e\u003c\/tr\u003e\n\u003ctr\u003e\u003ctd\u003eCentre wavelength\u003c\/td\u003e\u003ctd\u003e656.28 nm\u003c\/td\u003e\u003c\/tr\u003e\n\u003ctr\u003e\u003ctd\u003eBandwidth (FWHM)\u003c\/td\u003e\u003ctd\u003e60 nm\u003c\/td\u003e\u003c\/tr\u003e\n\u003ctr\u003e\u003ctd\u003ePeak transmittance\u003c\/td\u003e\u003ctd\u003e95%\u003c\/td\u003e\u003c\/tr\u003e\n\u003ctr\u003e\u003ctd\u003eBlocking range\u003c\/td\u003e\u003ctd\u003e200-1100 nm (OD4)\u003c\/td\u003e\u003c\/tr\u003e\n\u003ctr\u003e\u003ctd\u003eCell\u003c\/td\u003e\u003ctd\u003eAluminum 6061, internal Ø178mm \/ external Ø184mm\u003c\/td\u003e\u003c\/tr\u003e\n\u003ctr\u003e\u003ctd\u003eSupplied as\u003c\/td\u003e\u003ctd\u003eGlass already mounted in cell\u003c\/td\u003e\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003ch2\u003eFrequently asked questions\u003c\/h2\u003e\n\u003cp\u003e\u003cstrong\u003eDoes the ERF replace the H-alpha filter?\u003c\/strong\u003e No, it's a pre-filter: it must always be used together with an H-alpha filter (Daystar or Solar Spectrum), never alone.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eIs it ready to mount?\u003c\/strong\u003e Yes, unlike filters sold as glass only, this version already includes the aluminium cell.\u003c\/p\u003e\n\n\u003ch2\u003e⚠️ Safety warning\u003c\/h2\u003e\n\u003cp\u003eThe ERF filter must \u003cstrong\u003ealways be mounted in front of\u003c\/strong\u003e the telescope aperture, with the coated side facing the Sun, and used \u003cstrong\u003eexclusively together with an H-alpha filter\u003c\/strong\u003e. Improper use in direct visual observation can cause severe, permanent eye damage.\u003c\/p\u003e","brand":"Artesky","offers":[{"title":"Default Title","offer_id":57940850934091,"sku":"AKERF-130-MC178","price":999.0,"currency_code":"EUR","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0886\/1981\/1147\/files\/filtro-di-rigetto-erf-130mm-con-cella-in-metallo.jpg?v=1784962606","url":"https:\/\/adriasky.it\/en\/products\/artesky-erf-filter-130mm-cell-178mm","provider":"Adriasky","version":"1.0","type":"link"}