What is the purpose of the Orion Optics UK 85mm Fixed Adaptor Ring?
This adaptor ring serves one critical function: to add exactly 10mm of spacing into an 85mm-threaded optical train. This is most often required to achieve the precise back focus distance specified by a coma corrector or field flattener to ensure a flat, sharp field of view for astrophotography.
How do I know if I need the 10mm BFD adaptor ring for my setup?
You need this 10mm ring if the total back focus requirement of your corrector (e.g., 55mm) minus the back focus of your camera and other accessories (like a filter wheel or off-axis guider) leaves a 10mm gap. Always calculate the total spacing of your existing components first to determine the exact extension length you need.
What is the advantage of a fixed 10mm ring over a variable spacer?
A fixed ring like this Orion Optics UK 85mm adaptor offers superior rigidity and stability. Variable spacers can introduce flex or tilt into the imaging train, which can ruin an image by causing elongated stars in the corners. A fixed, solid ring ensures all components are held perfectly parallel, which is crucial for high-resolution imaging.
Will the 85mm fixed adaptor ring introduce tilt in my imaging train?
No, the primary benefit of a high-quality fixed adaptor is its ability to prevent tilt. It is machined to tight tolerances to ensure flat, parallel faces. This provides a much more secure and orthogonal connection between optical components than adjustable or multi-part solutions, preserving the alignment of your imaging system.
I'm using an Orion Optics UK ODK telescope. Is the 10mm BFD ring the right part to achieve focus with my camera?
It depends entirely on your specific corrector and camera combination. Orion Optics UK systems have precise back focus requirements. You must consult the documentation for your specific corrector (e.g., the Optimized Dall-Kirkham's corrector) to find its required back focus distance, then measure the back focus of your camera and any other accessories. This 10mm ring is the correct choice only if your calculation reveals a 10mm spacing deficit.
Is this 85mm adaptor ring compatible with accessories from other brands?
While designed by Orion Optics UK, this adaptor should be compatible with any component that uses a standard 85mm thread. However, it is crucial to verify the thread pitch and type (e.g., M85x1) of your existing components to ensure a proper fit. Compatibility is based on matching mechanical dimensions, not brand names.
