{"product_id":"astronomy-plus-energy-rejection-filters-w-metal-cover","title":"Astronomy Plus Energy Rejection Filters W. Metal Cover","description":"\u003ch1\u003eAstronomy Plus Energy Rejection Filters\u003c\/h1\u003e\n\u003cp\u003e\u003cspan style=\"background-color: #ffffff; color: #000000; font-size: 18px; font-family: Poppins, sans-serif;\" data-spm-anchor-id=\"a2g0o.detail.1000023.i3.6a17IxziIxziY9\"\u003eSuitable for Quark with refracting and reflecting telescope to observe and photograph the solar prominence chromosphere\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"background-color: #ffffff; color: #000000; font-size: 18px; font-family: Poppins, sans-serif;\"\u003eUltra-high precision, the lens accuracy is guaranteed to meet the requirements of solar photography and imaging\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"background-color: #ffffff; color: #000000; font-size: 18px; font-family: Poppins, sans-serif;\"\u003eIf you are a demanding professional sun photographer - this product is for you!\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"background-color: #ffffff; color: #009ce0; font-size: 18px; font-family: Poppins, sans-serif;\"\u003e\u003cstrong\u003eWhy use an ERF for solar photography?\u003c\/strong\u003e\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"background-color: #ffffff; color: #000000; font-size: 16px; font-family: Poppins, sans-serif;\"\u003eThe purpose of using an Energy Rejection Filter (ERF) is to prevent as much solar energy as possible from entering the telescope in the first place, thereby avoiding excessive heating of the H-alpha filter etalon.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cspan style=\"background-color: #ffffff; color: #000000; font-size: 16px; font-family: Poppins, sans-serif;\"\u003eThis effect can be effectively achieved by adding an ERF filter to the front of the telescope. At the same time, the air inside the barrel is prevented from heating up - the telescope remains close to ambient temperature and there is no air turbulence inside the barrel due to the temperature difference. If we look at the solar spectrum, we see that this filter mostly blocks visible light. Ideally, it reflects solar energy rather than absorbs it, and doesn't heat itself up in the process - that's why these filters are called Energy Rejection Filters (ERF for short).\u003c\/span\u003e\u003c\/p\u003e\n\u003ch3\u003e\u003cspan style=\"background-color: #ffffff; color: #000000; font-size: 16px; font-family: Poppins, sans-serif;\"\u003eTechnical Specifications\u003c\/span\u003e\u003c\/h3\u003e\n\u003cdiv\u003eEdge chipping: \u0026lt;0.2mm\u003c\/div\u003e\n\u003cdiv\u003eThickness (mm): 12mm\u003c\/div\u003e\n\u003cdiv\u003eSurface shape: λ\/4\u003c\/div\u003e\n\u003cdiv\u003eFinish: 60-40\u003c\/div\u003e\n\u003cdiv\u003eCenter wavelength (nm): 656.28\u003c\/div\u003e\n\u003cdiv\u003eBandwidth (nm): 60\u003c\/div\u003e\n\u003cdiv\u003ePeak transmittance (%): 95%\u003c\/div\u003e\n\u003cdiv\u003eCutoff range (nm): 200nm-1100nm\u003c\/div\u003e\n\u003cdiv data-spm-anchor-id=\"a2g0o.detail.1000023.i4.6a17IxziIxziY9\"\u003eCutoff Depth (OD): OD4\u003c\/div\u003e\n\u003cdiv data-spm-anchor-id=\"a2g0o.detail.1000023.i4.6a17IxziIxziY9\"\u003e\n\u003cp\u003e \u003c\/p\u003e\n\u003ch2\u003e\u003cspan style=\"background-color: #ffffff; color: #000000; font-size: 16px; font-family: Poppins, sans-serif;\"\u003eAvailable diameters:\u003c\/span\u003e\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\u003cspan style=\"background-color: #ffffff; color: #000000; font-size: 16px; font-family: Poppins, sans-serif;\"\u003e100mm\u003cimg src=\"https:\/\/admin.shopify.com\/store\/lirelanature\/products\/new\"\u003e\u003c\/span\u003e\u003c\/li\u003e\n\u003cli\u003e\u003cspan style=\"background-color: #ffffff; color: #000000; font-size: 16px; font-family: Poppins, sans-serif;\"\u003e130mm\u003c\/span\u003e\u003c\/li\u003e\n\u003cli\u003e\u003cspan style=\"background-color: #ffffff; color: #000000; font-size: 16px; font-family: Poppins, sans-serif;\"\u003e150mm\u003c\/span\u003e\u003c\/li\u003e\n\u003cli\u003e\u003cspan style=\"background-color: #ffffff; color: #000000; font-size: 16px; font-family: Poppins, sans-serif;\"\u003e200mm\u003c\/span\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2 data-spm-anchor-id=\"a2g0o.detail.1000023.i4.6a17IxziIxziY9\"\u003eMetal Cover Version:\u003c\/h2\u003e\n\u003cdiv data-spm-anchor-id=\"a2g0o.detail.1000023.i4.6a17IxziIxziY9\"\u003e\n\u003cdiv\u003eMetal cover material: aluminum alloy (#6061)\u003c\/div\u003e\n\u003cdiv data-spm-anchor-id=\"a2g0o.detail.1000023.i5.6a17IxziIxziY9\"\u003eShell wall thickness: 4mm\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cp\u003e\u003c\/p\u003e\n\u003ch2\u003eAvailable metal Cover inner diameters:\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e148mm for 100mm filter\u003c\/li\u003e\n\u003cli\u003e178mm for 130mm filter\u003c\/li\u003e\n\u003cli\u003e230mm for 150mm filter\u003c\/li\u003e\n\u003cli\u003e248mm for 200mm filter\u003c\/li\u003e\n\u003cli\u003e330mm for 200mm filter\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eIn the Box\u003c\/h3\u003e\n\u003cp\u003e-Astronomy Plus Energy Rejection Filters with Metal Cover\u003c\/p\u003e\n\u003ch3\u003eManuals \u0026amp; Warranty\u003c\/h3\u003e\n\u003cp\u003e\u003ca rel=\"noopener\" href=\"https:\/\/rsg0f5oot8hl4gc1-65262452965.shopifypreview.com\/pages?preview_key=6fa22e2975bcff9aca13eec9e73a659c\" target=\"_blank\"\u003e1-Year Astronomy Plus Warranty\u003c\/a\u003e\u003c\/p\u003e\n\u003c\/div\u003e","brand":"Astronomy Plus","offers":[{"title":"Astronomy Plus 100mm ERF w. 148mm Metal Cover (ST-ERF100-C148)","offer_id":46806837199077,"sku":"AP-ST-ERF100-C148","price":731.0,"currency_code":"CAD","in_stock":true},{"title":"Astronomy Plus 130mm ERF w. 178mm Metal Cover (ST-ERF100-C178)","offer_id":46806837231845,"sku":"AP-ST-ERF100-C178","price":947.0,"currency_code":"CAD","in_stock":true},{"title":"Astronomy Plus 150mm ERF w. 230mm Metal Cover (ST-ERF150-C230)","offer_id":46806837264613,"sku":"AP-ST-ERF150-C230","price":1179.0,"currency_code":"CAD","in_stock":true},{"title":"Astronomy Plus 200mm ERF w. 248mm Metal Cover (ST-ERF200-C248)","offer_id":46806837297381,"sku":"AP-ST-ERF200-C248","price":1958.0,"currency_code":"CAD","in_stock":true},{"title":"Astronomy Plus 200mm ERF w. 330mm Metal Cover (ST-ERF200-C330)","offer_id":46806837330149,"sku":"AP-ST-ERF200-C330","price":2040.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0652\/6245\/2965\/files\/Screenshot2025-05-31111900.png?v=1779999508","url":"https:\/\/istronomyplus.com\/products\/astronomy-plus-energy-rejection-filters-w-metal-cover","provider":"Astronomy Plus – Telescopes \u0026 Astrophotography Canada","version":"1.0","type":"link"}