{"id":113157,"date":"2026-10-09T16:54:01","date_gmt":"2026-10-09T14:54:01","guid":{"rendered":"https:\/\/www.telescoop.nl\/?post_type=product&#038;p=113157"},"modified":"2026-10-13T11:14:24","modified_gmt":"2026-10-13T09:14:24","slug":"legacy-prefilter-e-120n80-for-h-alpha-solar-warning-daystar","status":"publish","type":"product","link":"https:\/\/www.telescoop.nl\/en\/erf-voorfilter-e-120n80-voor-h-alpha-zonnewaarneming-daystar\/","title":{"rendered":"ERF-prefilter E-120N80 for H-alpha solar monitoring | DayStar"},"content":{"rendered":"<p class=\"wp-block-paragraph\">An H-alpha setup does not start at the filter at the back of the telescope, but at the front of the telescope. An energy rejection filter like the DayStar ERF E-120N80 sits in front of the opening and blocks ultraviolet and infrared light and a large portion of visible light, while the red light around the H-alpha wavelength passes through.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">This keeps the heat in your telescope and on the H-alpha filter limited. The pre-filter works together with a narrowband H-alpha filter at the rear, for example <a href=\"https:\/\/www.telescoop.nl\/en\/h-alpha-filter-quantum-pe-05-a-for-the-chromosphere-of-the-sun-daystar\/\">a DayStar Quantum PE<\/a>.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Choose the ERF based on your telescope: the mount must fit snugly and securely on your tube or dovetail ring, without gaps where unfiltered sunlight can pass through. Therefore, first measure the outer diameter. Never look directly at the sun through an ERF alone and use it exclusively in conjunction with an appropriate H-alpha filter, as intended. Background can be found in <a href=\"https:\/\/www.telescoop.nl\/en\/the-sun-through-a-telescope\/\">view our guide on the sun<\/a>.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Other sizes are also available, such as <a href=\"https:\/\/www.telescoop.nl\/en\/legacy-pre-filter-e-120n100-for-h-alpha-solar-warning-daystar\/\">the ERF E-120N100<\/a>.<\/p>","protected":false},"excerpt":{"rendered":"<p>DayStar's E-120N80 pre-filter for H-alpha solar observation, which prevents heat, UV and infrared from entering your telescope before it opens.<\/p>","protected":false},"featured_media":113155,"comment_status":"open","ping_status":"closed","template":"","meta":{"_acf_changed":false},"product_brand":[3282],"product_cat":[56,3178],"product_tag":[],"class_list":["post-113157","product","type-product","status-publish","has-post-thumbnail","product_brand-daystar","product_cat-telescoop-accessoires","product_cat-zonnefilters","first","instock","taxable","shipping-taxable","purchasable","product-type-simple"],"bundled_by":[],"bundle_stock_status":"instock","bundle_stock_quantity":null,"bundle_virtual":false,"bundle_layout":"","bundle_add_to_cart_form_location":"","bundle_editable_in_cart":false,"bundle_sold_individually_context":"","bundle_item_grouping":"","bundle_min_size":"","bundle_max_size":"","bundle_price":[],"bundled_items":[],"bundle_sell_ids":[],"acf":[],"jetpack_sharing_enabled":true,"jetpack-related-posts":[{"id":113156,"url":"https:\/\/www.telescoop.nl\/en\/erf-voorfilter-e-110n75-voor-h-alpha-zonnewaarneming-daystar\/","url_meta":{"origin":113157,"position":0},"title":"ERF pre-filter E-110N75 for H-alpha solar monitoring | DayStar","author":"Info telescoop","date":"09-10-2026","format":false,"excerpt":"Energy rejection pre-filter E-110N75 from DayStar for opening your telescope, which prevents UV and infrared radiation during H-alpha observations.","rel":"","context":"Similar post","block_context":{"text":"Similar post","link":""},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2026\/10\/12827_1.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2026\/10\/12827_1.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2026\/10\/12827_1.jpg?resize=525%2C300&ssl=1 1.5x"},"classes":[]},{"id":113160,"url":"https:\/\/www.telescoop.nl\/en\/erf-voorfilter-e-140n100-voor-h-alpha-zonnewaarneming-daystar\/","url_meta":{"origin":113157,"position":1},"title":"ERF pre-filter E-140N100 for H-alpha solar monitoring | DayStar","author":"Info telescoop","date":"09-10-2026","format":false,"excerpt":"Size E-140N100 pre-filter for opening your telescope. It limits the heat on your H-alpha filter during observing the Sun.","rel":"","context":"Similar post","block_context":{"text":"Similar post","link":""},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2026\/10\/12827_1.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2026\/10\/12827_1.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2026\/10\/12827_1.jpg?resize=525%2C300&ssl=1 1.5x"},"classes":[]},{"id":113166,"url":"https:\/\/www.telescoop.nl\/en\/erf-voorfilter-e-325f90-voor-h-alpha-zonnewaarneming-daystar\/","url_meta":{"origin":113157,"position":2},"title":"ERF pre-filter E-325F90 for H-alpha solar monitoring | DayStar","author":"Info telescoop","date":"09-10-2026","format":false,"excerpt":"DayStar ERF pre-filter in size E-325F90 for opening your telescope, which keeps heat, UV and infrared out of your H-alpha setup.","rel":"","context":"Similar post","block_context":{"text":"Similar post","link":""},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2026\/10\/12827_1.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2026\/10\/12827_1.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2026\/10\/12827_1.jpg?resize=525%2C300&ssl=1 1.5x"},"classes":[]},{"id":113158,"url":"https:\/\/www.telescoop.nl\/en\/erf-voorfilter-e-120n100-voor-h-alpha-zonnewaarneming-daystar\/","url_meta":{"origin":113157,"position":3},"title":"ERF pre-filter E-120N100 for H-alpha solar monitoring | DayStar","author":"Info telescoop","date":"09-10-2026","format":false,"excerpt":"Energy rejection pre-filter E-120N100 from DayStar that protects your H-alpha filter and telescope from the heat, UV and infrared of the sun.","rel":"","context":"Similar 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post","link":""},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2026\/10\/12827_1.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2026\/10\/12827_1.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2026\/10\/12827_1.jpg?resize=525%2C300&ssl=1 1.5x"},"classes":[]},{"id":113159,"url":"https:\/\/www.telescoop.nl\/en\/erf-voorfilter-e-130n100-voor-h-alpha-zonnewaarneming-daystar\/","url_meta":{"origin":113157,"position":5},"title":"ERF pre-filter E-130N100 for H-alpha solar monitoring | DayStar","author":"Info telescoop","date":"09-10-2026","format":false,"excerpt":"ERF pre-filter in size E-130N100 that comes before your telescope and prevents heat, UV and infrared in an H-alpha configuration.","rel":"","context":"Similar post","block_context":{"text":"Similar 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