Eye tracking would allow even more latitude. The eye picks up very little detail outside of the central area of focus. It is also very good at inventing information to fill in any gaps - for example during the periods when the eyeball shifts position we are essentially blind but the brain fools us that we see a continuous image.
In Peter Watts' scifi novel "Blindsight"[1] there is a description of aliens which could program their bodies on the fly to move only during the saccades of one human observer in order to hide themselves[2].
