In accomplishing the object, according to one aspect of the present invention, there is provided {TAIL ~ a focus position} detecting {HEAD ~ method} comprising steps of: 
In accomplishing the object , according to one aspect of the present invention , there is provided { TAIL ~ a focus position } detecting { HEAD ~ method } comprising steps of :
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH