Before one can do any type of accurate work with an aerial camera, comprehensive knowledge of its calibration is mandatory. If you cannot secure the information from a reliable source or by means of measurements with your own laboratory equipment, you must consider the calibration an unknown factor and proceed accordingly.

You cannot tolerate unknown factors that might affect the accuracy or precision of your work. Therefore, do not attempt to make scientific deductions based on unknown or erroneous camera calibration information. You must know your camera thoroughly, including accurate knowledge of:

radial lens distortion

tangential lens distortion

calibrated focal length

transmission characteristics

spectral characteristics

resolution of lens

flatness of focal plane with respect to optical axis

accuracy of exposure at all shutter settings

position of reseau markings and all other fiducial marks

accuracy of any built-in accessories such as clocks, frame counters, altimeters, vacuum gages, data recorders, intervalometers, etc.