The GS-250AR is a 50 mm guide telescope with a focal brandlength of 250 mm (f\/5). The lens consists of three lenses with one ED element and a built-in field flattener. This ensures that stars remain sharp and round even to the edge of a 1-inch sensor, even with an IMX533.<\/p>\n
The AR version has a tooth-shaped focus that can support more weight. This allows you to mount a small camera like the AE676C on it to take wide-angle photos, or use it as a viewfinder. If you only want to guide, the lighter AC version is intended. Visually they are identical.<\/p>\n
As a rule of thumb: choose a guide scope with a focal brandlength between one-third and half of your main telescope. For a 750 mm telescope, 250 mm is a good fit.<\/p>\n
Hello<\/strong> who uses a refractor or Newton telescope with a focal brandlength of about 800 mm.<\/p>\n Not<\/strong> Anyone working with a long focal brandlength; then an off-axis guide such as the OAG-L is more accurate.<\/p>\n 50 mm guide scope with 250 mm focal length (f\/5). Triplet lens with ED elements and a flat field of view, suitable for guiding and for shooting with a small camera.<\/p>","protected":false},"featured_media":114507,"comment_status":"open","ping_status":"closed","template":"","meta":{"_acf_changed":false},"product_brand":[3365],"product_cat":[469,3064,3104,56],"product_tag":[],"class_list":["post-114510","product","type-product","status-publish","has-post-thumbnail","product_brand-touptek","product_cat-astro-fotografie","product_cat-guidescopes","product_cat-overige-astrofotografie-accessoires","product_cat-telescoop-accessoires","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":111636,"url":"https:\/\/www.telescoop.nl\/en\/zwo-seestar-s50-pro\/","url_meta":{"origin":114510,"position":0},"title":"ZWO Seestar S50 Pro","author":"Info telescoop","date":"25-08-2026","format":false,"excerpt":"The ZWO Seestar S50 Pro is the successor to the Seestar S50: 50 mm quadruplet APO (260 mm, f\/5.2), two 8.3 MP 4K sensors, a 63-degree wide-angle camera for the Milky Way up to 8K, three built-in filters, a 10,000 mAh battery (up to 9 hours), and 128 GB of storage. Four capture modes for...","rel":"","context":"With 5 comments","block_context":{"text":"With 5 comments","link":"https:\/\/www.telescoop.nl\/en\/zwo-seestar-s50-pro\/#comments"},"img":{"alt_text":"ZWO Seestar S50 Pro hero","src":"https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2026\/08\/zwo-seestar-s50-pro.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2026\/08\/zwo-seestar-s50-pro.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2026\/08\/zwo-seestar-s50-pro.jpg?resize=525%2C300&ssl=1 1.5x, https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2026\/08\/zwo-seestar-s50-pro.jpg?resize=700%2C400&ssl=1 2x"},"classes":[]}],"_links":{"self":[{"href":"https:\/\/www.telescoop.nl\/en\/wp-json\/wp\/v2\/product\/114510","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.telescoop.nl\/en\/wp-json\/wp\/v2\/product"}],"about":[{"href":"https:\/\/www.telescoop.nl\/en\/wp-json\/wp\/v2\/types\/product"}],"replies":[{"embeddable":true,"href":"https:\/\/www.telescoop.nl\/en\/wp-json\/wp\/v2\/comments?post=114510"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.telescoop.nl\/en\/wp-json\/wp\/v2\/media\/114507"}],"wp:attachment":[{"href":"https:\/\/www.telescoop.nl\/en\/wp-json\/wp\/v2\/media?parent=114510"}],"wp:term":[{"taxonomy":"product_brand","embeddable":true,"href":"https:\/\/www.telescoop.nl\/en\/wp-json\/wp\/v2\/product_brand?post=114510"},{"taxonomy":"product_cat","embeddable":true,"href":"https:\/\/www.telescoop.nl\/en\/wp-json\/wp\/v2\/product_cat?post=114510"},{"taxonomy":"product_tag","embeddable":true,"href":"https:\/\/www.telescoop.nl\/en\/wp-json\/wp\/v2\/product_tag?post=114510"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}Featured accessories<\/h3>\n
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Specifications<\/h3>\n
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\n Opening<\/strong><\/td>\n 50 mm<\/td>\n<\/tr>\n \n Focal length<\/strong><\/td>\n 250 mm<\/td>\n<\/tr>\n \n Opening ratio<\/strong><\/td>\n f\/5<\/td>\n<\/tr>\n \n Optics<\/strong><\/td>\n Three-sided with ED element and field surface marker<\/td>\n<\/tr>\n \n Corrected field of view<\/strong><\/td>\n 1 inch sensor<\/td>\n<\/tr>\n \n Camera connection<\/strong><\/td>\n 1.25 inch and M42x0.75<\/td>\n<\/tr>\n \n Focus<\/strong><\/td>\n dental bracket (AR)<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/figure>","protected":false},"excerpt":{"rendered":"