1. A panoramic image preparing method comprising a step of setting a measurement range so as to include objects to be measured, a step of dividing said measurement range as required and setting two or more sections and a step of synthesizing partial images photographed for each of said sections and preparing a panoramic image, a step of photographing each of said sections under two or more image pickup conditions and a step of synthesizing said panoramic image by using said partial image photographed under an optimal image pickup condition at least about said object to be measured.