An image pickup apparatus capable of preventing a decline of resolution of a still image while keeping a dynamic range of exposure control. The signalling data is decoded from the received two test data frames and transmitted back to the testing apparatus encoded in one frame. A nozzle touch block on a tip end portion of the pedestal is touched obliquely by the nozzle member of the melting cylinder. When in passive mode, sensors within the practice fish respond to light signals emitted at a certain frequency and wavelength reflected from a lure back to the practice fish.