It depends on the problem being addressed. Consistency can be hurt by using automatic settings since small changes in the scene will provoke dramatically different image settings by most cameras. If, for instance, one wanted to detect diseases of the skin, it would probably be helpful to establish (as best possible) uniform lighting conditions, and fixed camera settings (shutter speed, ISO, lens f-stop and any ancillary settings, such as color temperature adjustments, etc.). If, on the other hand, the goal was to identify individuals by their faces from arbitrary cameras, then a range of camera settings and image quality levels would be a more realistic representation of what the ultimate technical solution will be exposed to, during deployment.