Exposing a Suboptimal Exposure Mode in Observer-Directed Aerial Photography

In observer-directed archaeological aerial photography, the shutter-priority exposure mode may seem the obvious choice because it allows the photographer to guarantee a short exposure time. This paper argues that aperture-priority mode with Auto ISO and a maximum exposure-time limit offers a more controlled compromise: it keeps the aperture near the optical optimum, prevents the exposure time from becoming too long within the selected ISO range, and leaves ISO as the flexible exposure variable. Various scenario-based calculations show how the maximum acceptable exposure time varies with ground speed, flying height, focal length, photosite pitch, and the acceptable level of motion blur.