ABSTRACT
Prosumer cameras usually have mini-jack unbalanced inputs. Because they are unbalanced, long mic cables will be prone to noise pickup. Cameras that could shoot 16 mm film with optical soundtracks were being sold in the 1930s and used for newsreel and event filmmaking. Canon builds electronic XLR adapters that mount on the top or back of specific cameras. Instead of a transformer, they use op-amps to balance the mic inputs. The circuits are powered from a special jack on the camera, or by contacts on the adapter's hot shoe mount. The medieval microphones dealt with in the 1960s and 70s were driven by sound power. Just about every mic used on a film set runs on either batteries or phantom and has power to spare. Cameras and recorders have input impedances ranging from 500 to 2 k, and mic outputs can be as low as 100.
