{"product_id":"baader-planetarium-1-25-inch-filter-holder-for-t-2-and-2-inch-filter-threads","title":"Baader Planetarium 1.25\" Filter Holder for T-2 and 2\" Filter Threads","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003eSecurely holds standard 1.25\" filters\u003c\/li\u003e\n\u003cli\u003eIntegrates directly into T-2 (M42x0.75) threaded systems\u003c\/li\u003e\n\u003cli\u003ePrevents accessory tilt common with drop-in filter holders\u003c\/li\u003e\n\u003cli\u003eAdaptable for use in 2\" filter threads with optional ring\u003c\/li\u003e\n\u003cli\u003eLow-profile design minimizes added optical path length\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\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\u003e1.25\" Filter Holder for T-2 and 2\" Filter Threads\u003c\/h2\u003e\n\u003cp\u003eThe Baader 1.25\" Filter Holder provides a rigid, threaded solution for placing standard 1.25\" filters into any T-2 optical train, creating a secure connection that eliminates tilt. When used with optional adapters, it can achieve an optical path length of just 10 mm, and it can also be converted for use in standard 2\" filter threads, ensuring critical stability for heavy cameras, filter wheels, or an Atmospheric Dispersion Corrector (ADC).\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 1.25\" Filter Holder for Tilt-Free T-2 Connections\u003c\/h3\u003e\n\u003cp\u003eThis holder is engineered to solve a critical problem in astrophotography: accessory tilt. Unlike drop-in filter drawers or nosepieces that can introduce slight alignment errors, this unit screws directly into your T-2 threaded setup, forming a solid, flex-free connection. This ensures your filter remains perfectly orthogonal to the light path, which is essential for maintaining sharpness across the field with heavy imaging systems.\u003c\/p\u003e\n\u003cp\u003eBy installing the filter holder in one direction or the other, you can also make minor adjustments to the filter-to-sensor distance. This provides a small degree of spacing flexibility without needing additional extension rings, useful for fine-tuning back focus with specific reducers or correctors.\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\u003eAdapting to 2\" Systems and Managing Vignetting\u003c\/h3\u003e\n\u003cp\u003eWhile designed for T-2 systems, this holder can be adapted for use in any 2\" filter thread with the optional Baader Expanding Ring T-2f \/ M48m. This allows you to use a 1.25\" filter with a 2\" eyepiece or a camera that has a fixed 2\" filter thread and a smaller sensor.\u003c\/p\u003e\n\u003cp\u003eThe primary trade-off when using a 1.25\" filter in a 2\" light path is the potential for vignetting. This configuration is not recommended for wide-angle 2\" eyepieces or cameras with full-frame sensors, but it is a perfectly viable solution for planetary imaging cameras or visual use on-axis where the smaller illuminated field is not a limitation.\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\u003eScrew-In vs. Push-Fit: The #2458106 Alternative\u003c\/h3\u003e\n\u003cp\u003eBaader offers multiple ways to integrate 1.25\" filters, and this holder serves a specific purpose compared to push-fit solutions like the 1.25\" \/ T-2 plug-in adapter (#2458106). Where a push-fit adapter offers convenience for quick visual changes, this screw-in holder offers maximum security.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eSecurity for Imaging:\u003c\/strong\u003e For an imaging train with a heavy camera, ADC, and filter wheel, a fully threaded connection is non-negotiable. This holder guarantees that nothing can sag, tilt, or decenter during a long exposure.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePermanent Installation:\u003c\/strong\u003e You can install a specific filter—like a UV\/IR cut or a light pollution filter—semi-permanently within your optical train, knowing it will remain fixed and protected.\u003c\/li\u003e\n\u003c\/ul\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\"\u003eHow does this 1.25\" Filter Holder prevent tilt in my imaging train?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eBy using \u003cstrong\u003eT-2 (M42x0.75) threads\u003c\/strong\u003e to connect directly to other T-2 accessories, it creates a rigid, metal-on-metal connection. Unlike drop-in holders or nosepieces that rely on pressure screws, this threaded system ensures all components are perfectly aligned and locked in place, eliminating flexure even with heavy equipment like a cooled camera or filter wheel.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eCan I use the Baader 1.25\" Filter Holder with my 2\" eyepieces?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, but with a caveat. You will need the optional \u003cstrong\u003eBaader Expanding Ring T-2f \/ M48m (#2458110)\u003c\/strong\u003e to adapt the T-2 threads to standard 2\" filter threads. Be aware that using a 1.25\" filter with a wide-field 2\" eyepiece will likely cause significant vignetting (darkening at the edges of the view), as the filter is smaller than the eyepiece's field stop.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat is the advantage of this screw-in filter holder over a drop-in filter slide?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe primary advantage is \u003cstrong\u003estability\u003c\/strong\u003e. A screw-in holder becomes a structural part of the optical train, preventing any possibility of tilt or movement. Filter slides are convenient for changing filters quickly but can introduce minute alignment shifts that can affect flat-field calibration and edge-of-field star sharpness in demanding imaging applications.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIf I use this holder with my ZWO ASI533MC camera and T-2 accessories, will it cause vignetting?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eNo. The sensor in the ZWO ASI533MC is a 1-inch square format, which is well within the illumination circle provided by a 1.25\" filter. When used in a native T-2 threaded system, this filter holder will not cause vignetting with that camera.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWill this Baader filter holder work with a Q-Barlow lens?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, the holder accepts accessories with standard 1.25\" filter threads, including the Baader Q-Barlow lens element. However, due to the specific thread length on the Q-Barlow, it will only screw in about a quarter of a turn. This is sufficient to hold it securely for use.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhen imaging Jupiter with my ADC and a heavy camera, why is this Baader T-2 holder a better choice than a standard 1.25\" nosepiece?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eFor planetary imaging, maintaining perfect collimation and alignment through the entire optical train is critical. An ADC and a cooled planetary camera create a long, heavy lever arm. A standard 1.25\" nosepiece held by thumbscrews can easily tilt, throwing off both the ADC's correction and the camera's focus across the sensor. This \u003cstrong\u003eall-threaded T-2 holder\u003c\/strong\u003e prevents that tilt, ensuring the entire imaging system remains rigid and perfectly aligned with the telescope's optical axis.\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\u003eNet weight (kg)\u003c\/td\u003e\n\u003ctd\u003e0.03\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\" style=\"width:100%; text-align:center; font-style:italic;\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eBox contents for this product have not been specified.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"https:\/\/davidastro.com\/pages\/baader-planetarium-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eBaader Planetarium 2-Year Warranty\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Baader Planetarium","offers":[{"title":"Default Title","offer_id":52913178312989,"sku":"BAA-1508031","price":120.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/BaaderPlanetarium-1-Filter-Holder-for-T-2-and-2-Filter-Threads-1_ebe0f88c-3419-4f93-ae2d-d03ff78009f0.jpg?v=1789087318","url":"https:\/\/davidastro.com\/fr-us\/products\/baader-planetarium-1-25-inch-filter-holder-for-t-2-and-2-inch-filter-threads","provider":"David Astro","version":"1.0","type":"link"}