{"product_id":"tele-vue-2-4-inch-accessory-tube-0-25-inch-6-4mm","title":"Tele Vue 2.4\" Accessory Tube - 0.25\" (6.4mm)","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003eComponent Type: Fixed Extension Tube\u003c\/li\u003e\n\u003cli\u003eSystem Format: Tele Vue 2.4\" Imaging System\u003c\/li\u003e\n\u003cli\u003eOptical Length: 0.25\" (6.4mm)\u003c\/li\u003e\n\u003cli\u003eConnection Side 1: M61x1 Male Thread\u003c\/li\u003e\n\u003cli\u003eConnection Side 2: M61x1 Female Thread\u003c\/li\u003e\n\u003cli\u003eMaterial: Black Anodized Aluminum\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c!-- more --\u003e\n\u003cul class=\"tabs\"\u003e\n\u003cli class=\"active\"\u003eDescription\u003c\/li\u003e\n\u003cli\u003eFAQ\u003c\/li\u003e\n\u003cli\u003eSpecifications\u003c\/li\u003e\n\u003cli\u003eIn the Box\u003c\/li\u003e\n\u003cli\u003eDownloads\u003c\/li\u003e\n\u003cli\u003eWarranty\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cul class=\"tabs-content\"\u003e\n\u003cli class=\"active\"\u003e\n\u003cdiv\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section-center\"\u003e\n\u003ch2\u003eDial In Perfect Back Focus with the Tele Vue 2.4\" Accessory Tube\u003c\/h2\u003e\n\u003cp\u003eThe Tele Vue 2.4\" Accessory Tube TLA-0250 is a precision-machined 6.4mm (0.25\") spacer for the Tele Vue imaging system, designed to help astrophotographers achieve the exact back focus required by their specific camera and reducer or flattener combination. This component is not merely an extension; it is a critical part of maintaining the geometric precision of your optical train, ensuring every connection is rigid, square, and internally dark. For imagers using Tele Vue's large-format refractors like the NP127is and NP101is, these tubes are the fundamental building blocks for creating a flat field with sharp stars from corner to corner.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eThe Foundation of a Rigid Imaging Train: The 2.4\" Format\u003c\/h3\u003e\n\u003cp\u003eModern astrophotography demands an optical train that is completely free of flexure and tilt, especially when using large, heavy cameras. The Tele Vue 2.4\" accessory ecosystem was engineered specifically to meet this demand. This 0.25\" extension tube shares that same large-diameter format, preventing the vignetting and mechanical instability that can occur when adapting down to smaller 2\" components. The result is a solid, wide-aperture light path from the focuser to the camera sensor, preserving the full performance of your Tele Vue refractor.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eAchieving Precise Back Focus with a 6.4mm Extension\u003c\/h3\u003e\n\u003cp\u003eEvery reducer, flattener, and corrector has an optimal distance at which it must be placed from the camera sensor to produce a perfectly flat field. The TLA-0250 provides a fixed, repeatable 6.4mm of spacing, allowing you to methodically build out your optical train to match that requirement. Using fixed tubes like this one eliminates the potential for drift or error associated with variable-length adapters, providing a set-and-forget solution for your dedicated imaging setup. It's the right choice when you know the exact spacing you need and demand absolute consistency night after night.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eSecure and Square M61 Threaded Connections\u003c\/h3\u003e\n\u003cp\u003eThe integrity of your imaging train depends on its connections. The TLA-0250 uses Tele Vue's M61x1 threading on both male and female ends, ensuring a direct, metal-to-metal contact that is far more secure than compression rings or set screws. This threaded design locks the components together, maintaining perfect optical alignment and preventing any possibility of tilt as the telescope moves across the sky. This rigidity is what translates the theoretical performance of your optics into a reality on your sensor, producing consistently round stars across the entire frame.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eMaximizing Contrast with Anti-Reflection Interior\u003c\/h3\u003e\n\u003cp\u003eIn a high-performance imaging system, controlling stray light is paramount for achieving high-contrast results. Every internal surface of the TLA-0250 accessory tube is machined with micro-baffles and finished in a deep, matte black to absorb off-axis reflections. This attention to detail ensures that the only light reaching your sensor is the focused image from your telescope, not scattered light bouncing within the adapter. This maximizes the signal-to-noise ratio, allowing the faintest wisps of nebulosity and delicate galaxy details to stand out against a dark sky background.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eBuilding Your Perfect Imaging Train with Tele Vue Spacers\u003c\/h3\u003e\n\u003cp\u003eThis 6.4mm tube is one of several fixed-length spacers in the Tele Vue 2.4\" family. Astrophotographers often combine multiple tubes to precisely hit their target back focus. For example, if your setup requires 15.9mm of spacing, you could combine this 6.4mm tube (TLA-0250) with the 9.5mm tube (TLB-0375). This modular approach provides a robust and reliable alternative to single, often less-rigid, adjustable spacers. The primary limitation of this component is its specificity; it is designed exclusively for the Tele Vue 2.4\" ecosystem and is not compatible with standard 2\" focusers or accessories.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eThe Final Millimeters to a Perfect Image\u003c\/h3\u003e\n\u003cp\u003eThe experience of using a precision spacer isn't about the component itself, but the image it makes possible. Imagine processing your data and finding that the stars in the corners of your full-frame sensor are just as tight and round as the ones in the center. That is the direct visual consequence of achieving correct back focus. This 6.4mm accessory tube is often the final, critical piece of the puzzle that turns a good image with slight star elongation at the edges into a flawless, professional-quality astrophoto ready for publication.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat is this Tele Vue accessory tube used for?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThis is a precision 6.4mm (0.25\") spacer used to set the correct back focus distance between a field flattener or reducer and a camera sensor. It is designed specifically for Tele Vue's 2.4\" imaging systems, such as those on the NP101is and NP127is telescopes.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWill this Tele Vue tube work with my standard 2-inch focuser?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eNo. This accessory tube is part of the larger Tele Vue 2.4\" ecosystem and uses M61x1 threads. It is not compatible with standard 2\" focusers that use compression rings or M48 threads.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow do I know which spacer length I need?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eConsult the documentation for your specific field flattener or reducer, which will state the required back focus in millimeters (typically 55mm). You then subtract your camera's sensor depth and any other adapters to find the remaining distance you need to fill with spacers like this one.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan I stack multiple Tele Vue 2.4\" tubes together?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, these tubes are designed to be stacked. Combining different lengths (e.g., this 6.4mm tube with a 9.5mm or 12.7mm tube) is the standard method for achieving a precise, custom back focus distance with maximum rigidity.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIs a fixed spacer better than an adjustable one?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eFor a dedicated imaging setup, a stack of fixed spacers like this one is generally considered more rigid and less prone to tilt than a helical or sliding adjustable spacer. If your back focus requirement is constant, fixed tubes provide superior mechanical stability.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eProduct Name\u003c\/td\u003e\n\u003ctd\u003eTele Vue 2.4\" Accessory Tube - 0.25\"\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePart Number\u003c\/td\u003e\n\u003ctd\u003eTLA-0250\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOptical Length \/ Spacing\u003c\/td\u003e\n\u003ctd\u003e0.25\" (6.4mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSystem Interface\u003c\/td\u003e\n\u003ctd\u003eTele Vue 2.4\" Imaging System\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eThread Type (Both Sides)\u003c\/td\u003e\n\u003ctd\u003eM61 x 1.0\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOuter Diameter\u003c\/td\u003e\n\u003ctd\u003e~2.6\" (66mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eClear Aperture\u003c\/td\u003e\n\u003ctd\u003e~2.3\" (58mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMaterial\u003c\/td\u003e\n\u003ctd\u003eBlack Anodized Aluminum\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eWeight\u003c\/td\u003e\n\u003ctd\u003e1.2 oz (34g)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eTele Vue 2.4\" Accessory Tube - 0.25\" (6.4mm)\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Tele_Vue_Tubes_and_Spacers_Set_2.4-inch_Manual.pdf\" target=\"_blank\"\u003e\u003csvg class=\"DAV-img-box\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"\u003e\u003cpath d=\"M0 64C0 28.7 28.7 0 64 0L224 0l0 128c0 17.7 14.3 32 32 32l128 0 0 144-208 0c-35.3 0-64 28.7-64 64l0 144-48 0c-35.3 0-64-28.7-64-64L0 64zm384 64l-128 0L256 0 384 128zM176 352l32 0c30.9 0 56 25.1 56 56s-25.1 56-56 56l-16 0 0 32c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-48 0-80c0-8.8 7.2-16 16-16zm32 80c13.3 0 24-10.7 24-24s-10.7-24-24-24l-16 0 0 48 16 0zm96-80l32 0c26.5 0 48 21.5 48 48l0 64c0 26.5-21.5 48-48 48l-32 0c-8.8 0-16-7.2-16-16l0-128c0-8.8 7.2-16 16-16zm32 128c8.8 0 16-7.2 16-16l0-64c0-8.8-7.2-16-16-16l-16 0 0 96 16 0zm80-112c0-8.8 7.2-16 16-16l48 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 32 32 0c8.8 0 16 7.2 16 16s-7.2 16-16 16l-32 0 0 48c0 8.8-7.2 16-16 16s-16-7.2-16-16l0-64 0-64z\" fill=\"#0047a7\"\u003e\u003c\/path\u003e\u003c\/svg\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eDownload Manual\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"https:\/\/davidastro.com\/pages\/tele-vue-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eTele Vue 5-Year Limited Warranty\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"TeleVue","offers":[{"title":"Default Title","offer_id":51223884235037,"sku":"TV-TLA-0250","price":55.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Tele_Vue_2.4in_Accessory_Tube_0.25in_1.jpg?v=1777515016","url":"https:\/\/davidastro.com\/fr\/products\/tele-vue-2-4-inch-accessory-tube-0-25-inch-6-4mm","provider":"David Astro","version":"1.0","type":"link"}