{"lens":{"id":"canon-ef","displayName":"Canon EF","manufacturer":"Canon","flangeDistanceMm":44,"electronicProtocol":"Canon EF"},"body":{"id":"canon-fd","displayName":"Canon FD","manufacturer":"Canon","flangeDistanceMm":42,"electronicProtocol":"mechanical-only"},"compat":{"lensMountId":"canon-ef","bodyMountId":"canon-fd","feasibility":"mechanical","af":"manual-only","is":"lens-only","aperture":"adapter-wheel","infinityFocus":"yes","adapterExamples":["generic mechanical adapter ring (multiple vendors)"],"caveats":["Mechanical adapter only — no electronic communication between Canon EF lens and Canon FD body.","Lens has no aperture ring; choose an adapter with a built-in aperture-control wheel."],"formatNote":{"match":"match","lensFormat":"full-frame","bodyFormat":"full-frame","cropFactor":null,"message":"Lens image circle (full-frame) matches body sensor (full-frame) — no crop or vignetting concern."}}}