{"lens":{"id":"canon-ef-s","displayName":"Canon EF-S","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-s","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-S lens and Canon FD body.","Lens has no aperture ring; choose an adapter with a built-in aperture-control wheel."],"formatNote":{"match":"lens-smaller-than-body","lensFormat":"APS-C","bodyFormat":"full-frame","cropFactor":null,"message":"Lens image circle (APS-C) is smaller than body sensor (full-frame) — expect heavy vignetting or black corners. Many bodies auto-crop to the smaller format and drop resolution accordingly."}}}