Review of methods for animal videography using camera systems that automatically move to follow the animal.

Digital photography and videography provide rich data for the study of animal behavior and are consequently widely used techniques. For fixed, unmoving cameras, the image sensor and optics govern the field of view and spatial detail. For a given sensor resolution, the optics determine a tradeoff between high magnification in which high spatial detail from a restricted field of view is obtained versus low magnification in which lower spatial detail is obtained from a larger region. In addition to this geometric resolution versus field of view tradeoff, limited light availability establishes a physical limit when imaging movement. If the animal is moving, motion blur smears the subject on the sensor during exposure. Practically, motion blur is further compounded by sensor inefficiency and noise. While these fundamental tradeoffs with stationary cameras can be sidestepped by employing multiple cameras and providing additional illumination, this may not always be desirable. An alternative that overcomes these issues of stationary cameras is to direct a high magnification camera at an animal continually as it moves. Here we review systems in which automatic tracking is used to maintain an animal in the working volume of a moving optical path. Such methods provide an opportunity to escape the tradeoff between resolution and field of view and also to reduce motion blur while still enabling automated image acquisition. We argue that further development will be useful and outline potential innovations that may improve the technology and lead to more widespread use.