{"id":112752,"date":"2026-10-09T16:52:07","date_gmt":"2026-10-09T14:52:07","guid":{"rendered":"https:\/\/www.telescoop.nl\/?post_type=product&p=112752"},"modified":"2026-10-09T20:30:49","modified_gmt":"2026-10-09T18:30:49","slug":"extension-tube-for-astrophotography-m54-m54-16-to-20-mm-askar","status":"publish","type":"product","link":"https:\/\/www.telescoop.nl\/en\/verlengbus-voor-astrofotografie-m54-m54-16-tot-20-mm-askar\/","title":{"rendered":"Extension tube for astrophotography, M54\/M54 16 to 20 mm | Askar"},"content":{"rendered":"

Your flattener or reducer only works properly if the camera sensor is at the correct distance. If the backfocus isn\u2019t correct, you\u2019ll see that in the corners of your footage. Therefore, when using an extension bus, pay attention to the length and the threaded connection, such as M54 or M48.<\/p>\n\n\n\n

This extension bus from Askar has M54 threaded connections and a length range of 16 to 20 mm. It belongs in the image chain between a flattener for astrophotography<\/a> or a reducer and your camera. If a part comes with T2 or M48 afterwards, then you might have an adapter between T2 and M48<\/a> needed.<\/p>\n\n\n\n

Calculate the entire image chain in advance: the backfocus that requires flattening or reduction, minus the length of the camera, filter holder, and other intermediate parts. This way you can see if this bus fills the gap that remains. Also check on each side which wire is inside and whether it is the inner or outer wire.<\/p>\n\n\n\n

If you want to be able to rotate your camera without having to unscrew anything, check out the camera rotator with M54 connection<\/a>.<\/p>","protected":false},"excerpt":{"rendered":"

Askar extension rod with M54 thread and a length range of 16 to 20 mm. To achieve the correct backfocus behind your flattener or reducer.<\/p>","protected":false},"featured_media":112749,"comment_status":"open","ping_status":"closed","template":"","meta":{"_acf_changed":false},"product_brand":[1542],"product_cat":[499,56],"product_tag":[],"class_list":["post-112752","product","type-product","status-publish","has-post-thumbnail","product_brand-askar","product_cat-adapters","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":112755,"url":"https:\/\/www.telescoop.nl\/en\/camerarotator-voor-astrofotografie-m54-m54-16-tot-20-mm-askar\/","url_meta":{"origin":112752,"position":0},"title":"Camera rotator for astrophotography, M54\/M54 16 to 20 mm | Askar","author":"Info telescoop","date":"09-10-2026","format":false,"excerpt":"Askar Rotator with M54 connection on both sides and a length of 16 to 20 mm. Rotate your camera around the optical axis without unscrewing anything.","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\/80946_1.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2026\/10\/80946_1.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2026\/10\/80946_1.jpg?resize=525%2C300&ssl=1 1.5x"},"classes":[]},{"id":112743,"url":"https:\/\/www.telescoop.nl\/en\/adapter-t2-m48-voor-cameras-en-accessoires-bij-astrofotografie-askar\/","url_meta":{"origin":112752,"position":1},"title":"Adapter T2\/M48 for cameras and accessories in astrophotography | Askar","author":"Info telescoop","date":"09-10-2026","format":false,"excerpt":"Askar coupling between T2 and M48 threaded connection. This way you can combine a camera, filter holder, flattener and reducer that don't fit together on their own.","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\/77140_3.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2026\/10\/77140_3.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2026\/10\/77140_3.jpg?resize=525%2C300&ssl=1 1.5x"},"classes":[]},{"id":112739,"url":"https:\/\/www.telescoop.nl\/en\/filterlade-voor-het-wisselen-van-filters-bij-astrofotografie-askar\/","url_meta":{"origin":112752,"position":2},"title":"Filter drawer for changing filters when photographing the night sky | Askar","author":"Info telescoop","date":"09-10-2026","format":false,"excerpt":"Replace filters without removing your camera: With this drawer from Askar, the orientation of your image remains consistent between shots.","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\/77055_1.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2026\/10\/77055_1.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2026\/10\/77055_1.jpg?resize=525%2C300&ssl=1 1.5x"},"classes":[]},{"id":94031,"url":"https:\/\/www.telescoop.nl\/en\/omegon-crayford-focuser-voor-newton-telescopen-2-inch\/","url_meta":{"origin":112752,"position":3},"title":"Omegon Crayford Focuser for Newton Telescopes 2 inch","author":"","date":"13-01-2026","format":false,"excerpt":"2-inch Crayford focuser for Newtonian telescopes, with metal housing, T2 and M54 threads, adjustable friction, and 2.5 kg payload capacity.","rel":"","context":"Similar 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