We present a robot navigation technique, termed circular navigation guidance (CNG), which solves the challenging problem of intercepting a moving target from a specific angle, using only data from a video camera. The guidance law is not split into path-planning and path-following stages, but is continuously updated based on immediately available information, making it practical even against a manoeuvring target, or where only incomplete information is available to the robot. This is achieved by converting a finite-time navigation problem into one of maintaining a certain geometric condition at all times. Theoretical and experimental results are presented, which support CNG as a practically useful tool for robot navigation.