obtaining a focus position of the object with {HEAD ~ respect} to {TAIL ~ the optical system} based on the evaluation function calculation values 
to
obtaining a focus position of the object with { HEAD ~ respect } to { TAIL ~ the optical system } based on the evaluation function calculation values
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH