{HEAD ~ a focus detection unit} configured to performing {TAIL ~ focus detection} on the basis of the phase difference detection signal 
{ HEAD ~ a focus detection unit } configured to performing { TAIL ~ focus detection } on the basis of the phase difference detection signal
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH