{"product_id":"william-optics-p-m92ex","title":"William Optics 4\" Extender for FLT Series","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003eAdds 67 mm of optical length to your imaging train\u003c\/li\u003e\n\u003cli\u003eFeatures M92 male and female threads for a secure connection\u003c\/li\u003e\n\u003cli\u003eDesigned for William Optics FLT 110 \u0026amp; FLT 132 refractors\u003c\/li\u003e\n\u003cli\u003eEnables focus with filter wheels, OAGs, and other accessories\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\u003eWilliam Optics 4\" Extender for FLT Series\u003c\/h2\u003e\n\u003cp\u003eThe William Optics 4\" Extender provides a fixed 67 mm of optical length for imaging trains on FLT series telescopes like the FLT 110 and FLT 132. It connects via male and female M92 threads, ensuring a rigid, non-flexing connection between the focuser and your camera or flattener, which is critical for achieving sharp, round stars across the field.\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\u003eM92 Threads and 67mm Extension for FLT 110 \u0026amp; FLT 132\u003c\/h3\u003e\n\u003cp\u003eDesigned specifically for the William Optics FLT 110 and FLT 132 refractors, this 4\" extender adds precisely 67 mm of back focus to your imaging setup. This additional length is often essential to reach focus with complex imaging trains that include accessories like filter wheels, off-axis guiders, and rotators.\u003c\/p\u003e\n\u003cp\u003eThe robust M92 male and female threads provide a secure, direct-threaded connection to the telescope's 4\" focuser. This eliminates the potential for tilt or flex that can occur with less secure slip-fit adapters, ensuring your entire imaging system remains perfectly aligned.\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\"\u003eWill this 4\" Extender help me reach focus with a filter wheel on my William Optics FLT 132?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, this is its primary purpose. The \u003cstrong\u003e67 mm of extension\u003c\/strong\u003e is designed to push the focal point outward, providing the necessary back focus to accommodate accessories like filter wheels and off-axis guiders that would otherwise prevent you from reaching focus.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat are the thread specifications for the William Optics 4\" Extender?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe extender uses \u003cstrong\u003eM92 threads\u003c\/strong\u003e. It features an M92 male thread on the light-in (telescope) side and an M92 female thread on the light-out (camera) side for a direct, secure connection.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIs the William Optics 4\" Extender compatible with telescopes other than the FLT 110 and FLT 132?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eWhile it is specifically engineered for the William Optics FLT 110 and FLT 132, it may work with other telescopes that feature a 4\" focuser with a female M92 thread. You must verify your telescope's specific thread size and back focus requirements before purchasing.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhy is it called a \"4\" Extender\" if it only provides 67 mm of extension?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe \"4\"\" designation refers to the size of the focuser it is designed to mate with, such as the 4\" focusers found on the FLT 110 and FLT 132 telescopes. The actual optical length it adds to the light path is \u003cstrong\u003e67 mm\u003c\/strong\u003e.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eI am trying to do prime focus imaging with a DSLR on my FLT 110 and can't reach focus. Is this extender the solution?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eIt depends on which way you need to move the focuser. If you cannot reach focus because the focuser is racked all the way \u003cstrong\u003eout\u003c\/strong\u003e, this 67 mm extender will provide the additional length needed to achieve a sharp image. If your focuser is racked all the way \u003cstrong\u003ein\u003c\/strong\u003e, you need less back focus, and this extender will not help.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eDoes the William Optics 4\" Extender have any optical elements?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eNo, this is a purely mechanical extender. It is a hollow tube designed only to increase the distance between the focuser and the camera. It contains no lenses and does not alter the focal length or focal ratio of your telescope.\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\u003eOptical Length\u003c\/td\u003e\n\u003ctd\u003e67 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTelescope Side Connection\u003c\/td\u003e\n\u003ctd\u003eM92 (male)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCamera Side Connection\u003c\/td\u003e\n\u003ctd\u003eM92 (female)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCompatibility\u003c\/td\u003e\n\u003ctd\u003eWilliam Optics FLT 110, FLT 132\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\"\u003e4\" Extender (M92, 67mm)\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\u003ca href=\"https:\/\/davidastro.com\/pages\/william-optics-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eWilliam Optics 2-Year Warranty\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"William Optics","offers":[{"title":"Default Title","offer_id":52853692039453,"sku":"WO-P-M92EX","price":68.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/WilliamOptics-4-Extender-1_f87949a8-1fb4-404a-b71a-b798be7c12da.jpg?v=1788457936","url":"https:\/\/davidastro.com\/en-us\/products\/william-optics-p-m92ex","provider":"David Astro","version":"1.0","type":"link"}