{"product_id":"orion-optics-uk-85mm-fixed-adaptor-ring-5mm-bfd","title":"Orion Optics UK 85mm Fixed Adaptor Ring (5mm BFD)","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e85mm Diameter Adaptor Ring\u003c\/li\u003e\n\u003cli\u003eProvides 5mm of Back Focus Distance (BFD)\u003c\/li\u003e\n\u003cli\u003eFixed, Non-Adjustable Spacer Design\u003c\/li\u003e\n\u003cli\u003eEnsures Rigid, Tilt-Free Connections\u003c\/li\u003e\n\u003cli\u003eManufactured by Orion Optics UK\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\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\u003eOrion Optics UK 85mm Fixed Adaptor Ring (5mm BFD)\u003c\/h2\u003e\n      \u003cp\u003eThe Orion Optics UK 85mm Fixed Adaptor Ring adds a precise 5mm of back focus distance to your imaging train, establishing the critical spacing required by field flatteners and coma correctors. With an inner diameter for 85mm-threaded components, this fixed-length ring provides a solid, non-flexing connection essential for long-exposure astrophotography.\u003c\/p\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv class=\"DAV-bg-light\"\u003e\n    \u003cdiv class=\"DAV-section\"\u003e\n      \u003ch3\u003eFixed 5mm Spacer: The Key to Correct Back Focus\u003c\/h3\u003e\n      \u003cp\u003eOptical correctors, such as field flatteners or coma correctors, only work when the camera sensor is placed at an exact distance from their rear lens element. This 5mm fixed ring is a simple, robust solution for closing a small gap in your imaging train to hit that perfect distance. Unlike variable spacers, its fixed 5mm length is absolute, removing any chance of incorrect adjustment or slippage during an imaging run.\u003c\/p\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv class=\"DAV-bg-light\"\u003e\n    \u003cdiv class=\"DAV-section\"\u003e\n      \u003ch3\u003e85mm Threaded Connection for Maximum Rigidity\u003c\/h3\u003e\n      \u003cp\u003eFor elite astrophotography, every component in the optical path must be rigidly secured to prevent tilt, which can elongate stars in the corners of your images. This Orion Optics UK 85mm adaptor provides a solid, threaded connection that maintains perfect alignment between your camera and telescope optics. Its precision-machined build ensures that your sensor remains perfectly perpendicular to the light path, preserving the sharpness your telescope is capable of delivering.\u003c\/p\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n  \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eWhat is the purpose of the Orion Optics UK 85mm Fixed Adaptor Ring?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eThis adaptor ring is a precision spacer designed to add exactly \u003cstrong\u003e5mm of back focus distance\u003c\/strong\u003e to an astrophotography imaging train. It's used to achieve the precise sensor-to-corrector distance required by field flatteners, reducers, or coma correctors for sharp, well-formed stars across the entire image.\u003c\/p\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eWhy should I use the 5mm fixed adaptor instead of an adjustable spacer?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eA fixed spacer like the Orion Optics UK 5mm ring offers superior \u003cstrong\u003erigidity and reliability\u003c\/strong\u003e. Adjustable spacers can sometimes introduce tilt or slip under the weight of a heavy camera. A fixed ring provides a solid, non-moving connection, ensuring perfect optical alignment is maintained throughout your imaging session.\u003c\/p\u003e\n  \u003c\/div\u003e\n    \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eHow do I know if I need this 5mm BFD adaptor for my setup?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eCalculate the total back focus of your current imaging train. Start with the back focus requirement of your corrector (e.g., 55mm), then subtract the back focus provided by your camera, off-axis guider, and filter wheel. If the remaining gap is 5mm, this Orion Optics UK 85mm adaptor is the correct part to achieve perfect spacing.\u003c\/p\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eWill the Orion Optics UK 85mm adaptor introduce any tilt into my imaging train?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eNo. The adaptor is precision-machined by Orion Optics UK to ensure its surfaces are perfectly parallel. When threaded correctly, it maintains the alignment of your optical components and is designed specifically to \u003cstrong\u003eeliminate sources of tilt\u003c\/strong\u003e, not create them.\u003c\/p\u003e\n  \u003c\/div\u003e\n    \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eWill this 85mm adaptor work with my full-frame camera and Orion Optics UK telescope to avoid vignetting?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eThe large 85mm diameter of this adaptor is designed to provide a wide, clear light path, making it suitable for systems using large correctors and full-frame sensors. It helps ensure that the field illumination from the telescope's optics is not constricted, minimizing vignetting on larger camera sensors.\u003c\/p\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eI'm connecting my AGX Newtonian's coma corrector to a filter wheel. How does the 85mm fixed adaptor help?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eThe coma corrector on an Orion Optics UK AGX Newtonian has a strict back focus requirement for optimal performance. This 85mm fixed adaptor ring can be used as part of the spacer combination between the corrector and your filter wheel to precisely make up the required distance, ensuring round stars to the edge of the field with your specific setup.\u003c\/p\u003e\n  \u003c\/div\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n  \u003ctable class=\"DAV-specifications\"\u003e\n    \u003ctbody\u003e\n      \u003ctr\u003e\n\u003ctd\u003eAdaptor Type\u003c\/td\u003e\n\u003ctd\u003eFixed Spacer Ring\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eDiameter\u003c\/td\u003e\n\u003ctd\u003e85mm\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eBack Focus Provided\u003c\/td\u003e\n\u003ctd\u003e5mm\u003c\/td\u003e\n\u003c\/tr\u003e\n      \u003ctr\u003e\n\u003ctd\u003eManufacturer\u003c\/td\u003e\n\u003ctd\u003eOrion Optics UK\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\u003c\/li\u003e\n\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\"\u003e85mm Fixed Adaptor Ring (5mm BFD)\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\n\u003cli\u003e\n\u003ca href=\"https:\/\/davidastro.com\/pages\/orion-optics-uk-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eOrion Optics UK 1-Year Warranty\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Orion Optics UK","offers":[{"title":"Default Title","offer_id":52942457504029,"sku":"OOUK-85MM-FIXED-ADAPTOR-RING-5MM","price":198.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Orion-Optics-UK-Logo_442a8800-b13b-4691-8467-527f6c9f4aa6.jpg?v=1789607641","url":"https:\/\/davidastro.com\/fr\/products\/orion-optics-uk-85mm-fixed-adaptor-ring-5mm-bfd","provider":"David Astro","version":"1.0","type":"link"}