You have just set the telescope up outside on the mount and when you focus, you notice that the stars are not centered. Then you want to quickly adjust the main mirror without having to look for tools. With these adjustment screws for the Vixen R200SS from Bob\u2019s Knobs, you can do that by hand.<\/p>\n\n\n\n
The R200SS is a 200 mm Newton, and with a Newton, good collimation is important for a sharp image. The knobs replace the screws on the back of the main mirror cell. You can find similar tubes at Individual Newton tubes<\/a>.<\/p>\n\n\n\n Replace the screws one by one so that the mirror stays securely in place. Then check the collimation with a collimation tip or a Omegon laser for Newtons<\/a>, and if necessary, adjust the viewfinder as well. More tips can be found in our explanation on adjusting the telescope<\/a>.<\/p>","protected":false},"excerpt":{"rendered":" Bob\u2019s Knobs for the main mirror cell of the Vixen R200SS. This allows you to adjust the mirror manually, even when the telescope is already outside.<\/p>","protected":false},"featured_media":112896,"comment_status":"open","ping_status":"closed","template":"","meta":{"_acf_changed":false},"product_brand":[1559],"product_cat":[56,3091],"product_tag":[],"class_list":["post-112897","product","type-product","status-publish","has-post-thumbnail","product_brand-bobs-knobs","product_cat-telescoop-accessoires","product_cat-telescoop-onderdelen","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":30386,"url":"https:\/\/www.telescoop.nl\/en\/bobs-knobs-afstelschroeven-voor-skywatcher-newton-secundaire-spiegel\/","url_meta":{"origin":112897,"position":0},"title":"Bob's Knobs Adjusting Screws for SkyWatcher Newton Secondary Mirror","author":"","date":"08-10-2025","format":false,"excerpt":"Bob's Knobs for the secondary mirror of Sky-Watcher Newtonians: collimating without a screwdriver above the open tube.","rel":"","context":"Similar post","block_context":{"text":"Similar post","link":""},"img":{"alt_text":"Bob\u2019s Knobs Afstelschroeven voor SkyWatcher Newton Secundaire Spiegel","src":"https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2025\/10\/Bobs-Knobs-Kartelschroeven-voor-vangspiegel-van-Skywatcher-Newton-tot-12-.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2025\/10\/Bobs-Knobs-Kartelschroeven-voor-vangspiegel-van-Skywatcher-Newton-tot-12-.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2025\/10\/Bobs-Knobs-Kartelschroeven-voor-vangspiegel-van-Skywatcher-Newton-tot-12-.jpg?resize=525%2C300&ssl=1 1.5x, https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2025\/10\/Bobs-Knobs-Kartelschroeven-voor-vangspiegel-van-Skywatcher-Newton-tot-12-.jpg?resize=700%2C400&ssl=1 2x, https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2025\/10\/Bobs-Knobs-Kartelschroeven-voor-vangspiegel-van-Skywatcher-Newton-tot-12-.jpg?resize=1050%2C600&ssl=1 3x, https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2025\/10\/Bobs-Knobs-Kartelschroeven-voor-vangspiegel-van-Skywatcher-Newton-tot-12-.jpg?resize=1400%2C800&ssl=1 4x"},"classes":[]},{"id":30381,"url":"https:\/\/www.telescoop.nl\/en\/bobs-knobs-springveren-voor-newton\/","url_meta":{"origin":112897,"position":1},"title":"Bob's Knobs springs for Newton","author":"","date":"08-10-2025","format":false,"excerpt":"Bob's Knobs collimation springs for 8 to 10 [Note: the original says 8 tot 12, so use 8 to 12] inch Newtonians: higher spring tension holds the primary mirror in place so that collimation is maintained.","rel":"","context":"Similar post","block_context":{"text":"Similar post","link":""},"img":{"alt_text":"Bob\u2019s Knobs springveren voor Newton ","src":"https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2025\/10\/Bobs-Knobs-Springveren-voor-hoofdspiegel-van-Newton-telescopen-van-8-tot-12-.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2025\/10\/Bobs-Knobs-Springveren-voor-hoofdspiegel-van-Newton-telescopen-van-8-tot-12-.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2025\/10\/Bobs-Knobs-Springveren-voor-hoofdspiegel-van-Newton-telescopen-van-8-tot-12-.jpg?resize=525%2C300&ssl=1 1.5x, https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2025\/10\/Bobs-Knobs-Springveren-voor-hoofdspiegel-van-Newton-telescopen-van-8-tot-12-.jpg?resize=700%2C400&ssl=1 2x, https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2025\/10\/Bobs-Knobs-Springveren-voor-hoofdspiegel-van-Newton-telescopen-van-8-tot-12-.jpg?resize=1050%2C600&ssl=1 3x, https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2025\/10\/Bobs-Knobs-Springveren-voor-hoofdspiegel-van-Newton-telescopen-van-8-tot-12-.jpg?resize=1400%2C800&ssl=1 4x"},"classes":[]},{"id":112857,"url":"https:\/\/www.telescoop.nl\/en\/afstelschroeven-voor-de-hoofdspiegel-van-een-10-inch-newton-bobs-knobs\/","url_meta":{"origin":112897,"position":2},"title":"Adjusting screws for the main mirror of a 10 inch Newton | Bob\u2019s Knobs","author":"Info telescoop","date":"09-10-2026","format":false,"excerpt":"Large adjustment buttons from Bob's Knobs for the main mirror cell of a 10-inch Newton. Alignment then takes place by hand.","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\/55356_1.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2026\/10\/55356_1.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2026\/10\/55356_1.jpg?resize=525%2C300&ssl=1 1.5x"},"classes":[]},{"id":112859,"url":"https:\/\/www.telescoop.nl\/en\/afstelschroeven-voor-de-hoofdspiegel-van-een-12-inch-newton-bobs-knobs\/","url_meta":{"origin":112897,"position":3},"title":"Adjusting screws for the main mirror of a 12 inch Newton | Bob\u2019s Knobs","author":"Info telescoop","date":"09-10-2026","format":false,"excerpt":"Bob's Knobs for the main mirror cell of a 12 inch Newton, which allows you to align the mirror without tools.","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\/55357_1.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2026\/10\/55357_1.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2026\/10\/55357_1.jpg?resize=525%2C300&ssl=1 1.5x"},"classes":[]},{"id":30378,"url":"https:\/\/www.telescoop.nl\/en\/bobs-knobs-afstelschroeven-voor-telrad-finder\/","url_meta":{"origin":112897,"position":4},"title":"Bob's Knobs Adjusting Screws for Telrad Finder","author":"Info telescoop","date":"08-10-2025","format":false,"excerpt":"Bob\u2019s Knobs for the Telrad: three stainless steel thumbscrews that allow you to precisely align the finder scope without tools.","rel":"","context":"Similar post","block_context":{"text":"Similar post","link":""},"img":{"alt_text":"Bob\u2019s Knobs Afstelschroeven voor Telrad Finder","src":"https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2025\/10\/Bobs-Knobs-Kartelschroeven-voor-Telrad-zoeker.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2025\/10\/Bobs-Knobs-Kartelschroeven-voor-Telrad-zoeker.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2025\/10\/Bobs-Knobs-Kartelschroeven-voor-Telrad-zoeker.jpg?resize=525%2C300&ssl=1 1.5x, https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2025\/10\/Bobs-Knobs-Kartelschroeven-voor-Telrad-zoeker.jpg?resize=700%2C400&ssl=1 2x, https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2025\/10\/Bobs-Knobs-Kartelschroeven-voor-Telrad-zoeker.jpg?resize=1050%2C600&ssl=1 3x, https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2025\/10\/Bobs-Knobs-Kartelschroeven-voor-Telrad-zoeker.jpg?resize=1400%2C800&ssl=1 4x"},"classes":[]},{"id":112893,"url":"https:\/\/www.telescoop.nl\/en\/afstelschroeven-voor-de-vangspiegel-van-een-6-inch-schmidt-newton-snt-bobs-knobs\/","url_meta":{"origin":112897,"position":5},"title":"Adjustment screws for the viewfinder of a 6 inch Schmidt-Newton (SNT) | Bob\u2019s Knobs","author":"Info telescoop","date":"09-10-2026","format":false,"excerpt":"Bob's Knobs for the viewfinder of a 6 inch Schmidt-Newton (SNT). Collimate with knobs instead of with a screwdriver.","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\/58080_1.jpg?resize=350%2C200&ssl=1","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2026\/10\/58080_1.jpg?resize=350%2C200&ssl=1 1x, https:\/\/i0.wp.com\/www.telescoop.nl\/wp-content\/uploads\/2026\/10\/58080_1.jpg?resize=525%2C300&ssl=1 1.5x"},"classes":[]}],"_links":{"self":[{"href":"https:\/\/www.telescoop.nl\/en\/wp-json\/wp\/v2\/product\/112897","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=112897"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.telescoop.nl\/en\/wp-json\/wp\/v2\/media\/112896"}],"wp:attachment":[{"href":"https:\/\/www.telescoop.nl\/en\/wp-json\/wp\/v2\/media?parent=112897"}],"wp:term":[{"taxonomy":"product_brand","embeddable":true,"href":"https:\/\/www.telescoop.nl\/en\/wp-json\/wp\/v2\/product_brand?post=112897"},{"taxonomy":"product_cat","embeddable":true,"href":"https:\/\/www.telescoop.nl\/en\/wp-json\/wp\/v2\/product_cat?post=112897"},{"taxonomy":"product_tag","embeddable":true,"href":"https:\/\/www.telescoop.nl\/en\/wp-json\/wp\/v2\/product_tag?post=112897"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}