{"lens":{"id":"m42","displayName":"M42 (Pentax / Praktica screw mount)","manufacturer":"Various","flangeDistanceMm":45.46,"electronicProtocol":"mechanical-only"},"body":{"id":"l-mount","displayName":"L-Mount","manufacturer":"Leica / Panasonic / Sigma","flangeDistanceMm":20,"electronicProtocol":"L-Mount"},"compat":{"lensMountId":"m42","bodyMountId":"l-mount","feasibility":"mechanical","af":"n/a","is":"n/a","aperture":"manual-ring","infinityFocus":"yes","adapterExamples":["generic mechanical adapter ring (multiple vendors)"],"caveats":["Mechanical adapter only — no electronic communication between M42 (Pentax / Praktica screw mount) lens and L-Mount body."],"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."}}}