{"id":113160,"date":"2026-10-09T16:54:08","date_gmt":"2026-10-09T14:54:08","guid":{"rendered":"https:\/\/www.telescoop.nl\/?post_type=product&p=113160"},"modified":"2026-10-13T11:14:24","modified_gmt":"2026-10-13T09:14:24","slug":"e-140n100-legacy-prefilter-for-h-alpha-solar-warning-daystar","status":"publish","type":"product","link":"https:\/\/www.telescoop.nl\/en\/erf-voorfilter-e-140n100-voor-h-alpha-zonnewaarneming-daystar\/","title":{"rendered":"ERF pre-filter E-140N100 for H-alpha solar monitoring | DayStar"},"content":{"rendered":"

An H-alpha filter at the back of your telescope can be vulnerable to the heat of a full beam of sunlight. Therefore, an H-alpha setup starts at a larger aperture with an energy rejection filter such as the DayStar ERF E-140N100. It blocks ultraviolet and infrared light and a large portion of visible light, allowing the red light around the H-alpha wavelength to pass through.<\/p>\n\n\n\n

You place the filter in front of the opening, on the tube or on a dew cap from your telescope<\/a>. In the rear it works together with an H-alpha filter, such as a DayStar Quark or a H-alpha filter from the Quantum series<\/a>.<\/p>\n\n\n\n

First check the outer diameter of your tube or dew cap, as the fitting should fit snugly and securely, with no gaps where unfiltered sunlight can pass through. A common mistake is to think that an ERF is itself a solar filter. That is not so: use it exclusively in conjunction with a suitable H-alpha filter. You can read more about the different types in our explanation about sunscreens<\/a>.<\/p>","protected":false},"excerpt":{"rendered":"

Size E-140N100 pre-filter for opening your telescope. It limits the heat on your H-alpha filter during observing the Sun.<\/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-113160","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":113159,"url":"https:\/\/www.telescoop.nl\/en\/erf-voorfilter-e-130n100-voor-h-alpha-zonnewaarneming-daystar\/","url_meta":{"origin":113160,"position":0},"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 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":113160,"position":1},"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":113156,"url":"https:\/\/www.telescoop.nl\/en\/erf-voorfilter-e-110n75-voor-h-alpha-zonnewaarneming-daystar\/","url_meta":{"origin":113160,"position":2},"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":113157,"url":"https:\/\/www.telescoop.nl\/en\/erf-voorfilter-e-120n80-voor-h-alpha-zonnewaarneming-daystar\/","url_meta":{"origin":113160,"position":3},"title":"ERF-prefilter E-120N80 for H-alpha solar monitoring | DayStar","author":"Info telescoop","date":"09-10-2026","format":false,"excerpt":"DayStar's E-120N80 pre-filter for H-alpha solar observation, which prevents 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