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It would be VERY difficult to synchronize focus of two advanced cameras with narrow DOF. You'd be better off with two humble fixed-focus "Flip" type videocameras. You must experiment by placing the cameras at various distances from eachother on your two-head tripod or board. For distant objects there will be no stereo effect of note unless the cameras are perhaps a meter or more apart. For close objects, the optimum distance might be 10cm. For insects, maybe only 1cm.