{"product_id":"svbony-sv161-1-25-double-helical-focuser","title":"SVBONY SV161 1.25″ Double Helical Focuser (M42 \/ T2)","description":"\u003cp\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/f9173b_20250806175428_5800_20260820163507_4921.webp?v=1791670355\" alt=\"SVBONY SV161 1.25″ double helical focuser\" style=\"max-width:100%;height:auto;\"\u003e\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe SVBONY SV161 is a 1.25″ double helical focuser with M42 x 0.75 (T2) threads on both ends: female on the telescope side, male on the camera side. It provides 10 mm of drawtube travel with 0.05 mm adjustment accuracy, ranging from 43 mm to 53 mm in height, and the drawtube does not rotate as you focus. A clamp screw locks the focus position. It is CNC-machined aerospace aluminium alloy with a frosted anodised finish and weighs 100 g.\u003c\/p\u003e\u003cp\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/f9173b-2_20250806175428_7977.webp?v=1791670355\" alt=\"SVBONY SV161 helical focuser side view\" style=\"max-width:100%;height:auto;\"\u003e\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eWho It's For\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThis is a good match if you are building or upgrading a guide scope, finder or small lens-based imaging setup and want fine, non-rotating focus for a guide camera or eyepiece, or if a telescope or telephoto lens has a coarse focuser that is hard to set precisely.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eKey Features \u0026amp; Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eDouble helical focusing:\u003c\/strong\u003e 10 mm of travel at 0.05 mm adjustment accuracy.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eNon-rotating drawtube:\u003c\/strong\u003e the camera or eyepiece, and the guide star field, keep their orientation while you focus.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eM42 x 0.75 both ends:\u003c\/strong\u003e female telescope side, male camera side, so T2 accessories attach without extra adapters.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eClamp screw:\u003c\/strong\u003e locks focus for long sessions, with an anti-skid brass screw.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCNC aerospace aluminium:\u003c\/strong\u003e frosted, anodised housing.\u003c\/li\u003e\n\u003c\/ul\u003e\u003cp\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/f9173b-3_20250806175428_6211.jpg?v=1791670355\" alt=\"SVBONY SV161 helical focuser thread detail\" style=\"max-width:100%;height:auto;\"\u003e\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eGuide scopes:\u003c\/strong\u003e SVBONY designs it for guide scopes such as its SV165 mini guide scope.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFinder and guide-camera focusing\u003c\/strong\u003e with a non-rotating field.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTelephoto lenses and small telescopes\u003c\/strong\u003e with sluggish focusing, used with a camera adapter.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003e\u003cstrong\u003eCompatibility and Accessory Notes\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eTelescope side:\u003c\/strong\u003e M42 x 0.75 female.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCamera side:\u003c\/strong\u003e M42 x 0.75 male, for T2 camera adapters such as Canon or Nikon T-rings (sold separately).\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e1.25″ inner diameter\u003c\/strong\u003e for 1.25″ accessories.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHeight:\u003c\/strong\u003e 43 mm minimum, 53 mm maximum, which is the figure to add to a backfocus calculation.\u003c\/li\u003e\n\u003c\/ul\u003e\u003cp\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/f9173b-4_20250806175428_7984.jpg?v=1791670355\" alt=\"SVBONY SV161 helical focuser with M3 screws\" style=\"max-width:100%;height:auto;\"\u003e\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eWhat's in the Box\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e1 x 1.25″ double helical focuser with female T2 thread\u003c\/li\u003e\n\u003cli\u003e3 x M3 screws\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003e\u003cstrong\u003eGood to Know Before You Order\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eTravel:\u003c\/strong\u003e 10 mm is designed for fine focusing; the optic needs to be close to focus already.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCamera adapters sold separately.\u003c\/strong\u003e If you are unsure what your setup needs, send us your guide scope and camera and we will work it out with you.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003e\u003cstrong\u003eFrequently Asked Questions\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eIs it difficult to set up?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eNo. It threads onto an M42 telescope or guide-scope connection, and the camera or adapter threads onto the top.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eDoes the camera rotate when I focus?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eNo. The drawtube keeps a fixed orientation.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eCan I lock the focus?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eYes. A clamp screw holds the focus position.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eIn short: a 100 g, M42-threaded double helical focuser with 10 mm of non-rotating travel and 0.05 mm accuracy for guide scopes, finders and small imaging optics.\u003c\/p\u003e","brand":"SvBony","offers":[{"title":"Default Title","offer_id":67722277355631,"sku":"F9173B","price":41.2,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/f9173b_20250806175428_5800_20260820163507_4921.webp?v=1791670355","url":"https:\/\/ontariotelescope.com\/products\/svbony-sv161-1-25-double-helical-focuser","provider":"Ontario Telescope and Accessories","version":"1.0","type":"link"}