{"product_id":"antares-m48-variable-camera-adapter-19-23mm","title":"Antares M48 Small Variable Camera Adapter (19-23)","description":"\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eThe Antares TEXT-48 is a variable-length M48 spacer for imaging trains. It carries M48 x 0.75 threads — male on one end, female on the other — and adjusts continuously through a \u003cstrong\u003e19-23 mm\u003c\/strong\u003e range of optical length. A locking ring secures the setting once it is dialled in, and the threading accepts 2″ filters.\u003c\/p\u003e\n\u003cp\u003eFocal reducers, field flatteners and Barlows each specify a backfocus distance from their rear surface to the sensor. Fixed spacers get you to that figure in discrete steps; this one covers an 18 mm span continuously, so the exact published number — or the number your own star tests settle on — is reachable without stacking shims.\u003c\/p\u003e\n\u003ch3\u003e\u003cstrong\u003eWho It’s For\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eThis is a good match if you:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eImage through a focal reducer, field flattener or corrector that calls for a specific backfocus and your current spacer stack lands beside it rather than on it.\u003c\/li\u003e\n\u003cli\u003eAre assembling an M48 imaging train and want the spacing to be adjustable rather than fixed at build time.\u003c\/li\u003e\n\u003cli\u003eSwap cameras, filter drawers or off-axis guiders between sessions and need to re-establish the same total optical length each time.\u003c\/li\u003e\n\u003cli\u003ePrefer to dial spacing in empirically, watching corner stars across a few test frames, instead of ordering a new fixed spacer for each attempt.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003e\u003cstrong\u003eKey Features \u0026amp; Design\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e19-23 mm continuous adjustment:\u003c\/strong\u003e an 18 mm span of optical length, set anywhere within the range rather than in fixed increments.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eM48 x 0.75 male and female:\u003c\/strong\u003e threads at both ends, so it drops into an existing M48 train in place of a fixed spacer without adding a thread change.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eLocking ring included:\u003c\/strong\u003e clamps the chosen length so the setting survives handling, transport and re-mounting.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMechanical only:\u003c\/strong\u003e no optical elements, no electrical connection — it sets separation and nothing else, and adds no aberrations of its own.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHybridisable with the TEXT-42:\u003c\/strong\u003e Antares publishes that the TEXT-48 and TEXT-42 can be combined to change the input or output thread of the assembly.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eSetting the published backfocus of a focal reducer or field flattener ahead of a cooled or DSLR camera.\u003c\/li\u003e\n\u003cli\u003eFine-tuning corner star shape by walking spacing across a few millimetres between test exposures.\u003c\/li\u003e\n\u003cli\u003eRe-establishing a known total optical length after swapping cameras or filter hardware in the same train.\u003c\/li\u003e\n\u003cli\u003eReplacing a stack of fixed M48 spacers and shims with one adjustable component.\u003c\/li\u003e\n\u003cli\u003eAdding a 2″ filter position to an M48 imaging train.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003e\u003cstrong\u003eCompatibility and Accessory Notes\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eThread standard:\u003c\/strong\u003e M48 x 0.75 on both ends — male one side, female the other.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWhere it sits:\u003c\/strong\u003e anywhere in an M48 train that needs its length set — typically between a reducer or flattener and the camera, filter drawer or off-axis guider.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eThread changes:\u003c\/strong\u003e Antares publishes that it can be hybridised with the \u003ca href=\"\/products\/adapter-camera-m42-variable\"\u003eTEXT-42 variable M42 adapter\u003c\/a\u003e to change the input or output thread of the combination. If you need an M48-to-M42 transition inside a variable spacer, that is the route Antares describes.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWorking out your total:\u003c\/strong\u003e backfocus is the sum of every component between the corrector and the sensor — this spacer, any filter drawer, the camera’s own sensor-to-flange distance, and filter glass thickness. Send us your camera, corrector and filter setup and we will work the total out with you.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003e\u003cstrong\u003eGood to Know Before You Order\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eIt is a spacer, not a corrector.\u003c\/strong\u003e There are no optical elements inside. It sets separation; the field correction comes from whatever reducer or flattener sits ahead of it.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eIt has no eyepiece holder.\u003c\/strong\u003e With M48 threads at both ends it belongs in a camera train — there is no 1.25″ or 2″ receptacle for visual use.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eThe range starts at 31 mm.\u003c\/strong\u003e If your train needs less than 31 mm of spacing at this point, a fixed low-profile spacer is the component for that job — get in touch and we will point you at the right one.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAntares does not publish a weight or outside diameter for this part.\u003c\/strong\u003e If either figure matters for your focuser load or a tight dew shield, get in touch and we will measure the one on the shelf.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003e\u003cstrong\u003eFrequently Asked Questions\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eIs it difficult to set up?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eNo. It threads into the train like any other M48 spacer, you extend or retract it to the length you want, and the locking ring holds it there. The work is in knowing your target backfocus figure — and if you tell us your corrector, camera and filters, we will calculate that number for you before you order.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat backfocus range does it cover?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e19-23 mm, continuously adjustable across that span rather than in fixed steps.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWill it fit my reducer or flattener?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eIf the corrector has an M48 x 0.75 output and your camera side is M48, yes. Correctors with M42\/T2 or M54 outputs need a thread change — Antares publishes that this adapter can be hybridised with the TEXT-42 to alter the input or output thread, and we can confirm what else the transition needs.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eCan I use it for visual observing?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eIt has M48 threads on both ends and no eyepiece receptacle, so it is built for a camera train. For visual spacing, a 1.25″ or 2″ extension tube is the right part.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eHow is this different from a set of fixed spacers?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eA fixed spacer gives one length; reaching a different figure means buying or re-stacking. This one covers 31–49 mm in a single component, which matters most while you are still finding the spacing that gives clean corners.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eDoes it need anything else to work?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eNo — the locking ring is included. What it needs is a train with M48 x 0.75 on both sides of it.\u003c\/p\u003e\n\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003eIn short: an M48 x 0.75 variable spacer covering 19-23 mm with a locking ring, for setting the backfocus a reducer or flattener asks for without stacking fixed shims. If you want the spacing total worked out before you order, send us your corrector, camera and filter details and we will do the arithmetic with you.\u003c\/p\u003e","brand":"Antares","offers":[{"title":"Default Title","offer_id":54290235981935,"sku":"TEXT-48S","price":44.99,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/173bb239-a760-4941-96f0-4fb00e0a496a.png?v=1789410947","url":"https:\/\/ontariotelescope.com\/products\/antares-m48-variable-camera-adapter-19-23mm","provider":"Ontario Telescope and Accessories","version":"1.0","type":"link"}