KINEMATICAL ANALYSIS OF ANIMAL BEHAVIOUR: THE CHALLENGE TO INCREASE THE FRAME RATE IN DIGITAL HIGH-SPEED CINEMATOGRAPHY

Modern digital high-speed film systems are able to capture sequences by extremely high frame rates - over 100 000 fr/s. The equipment costs for such systems are high but the operational costs are practically zero. An important advantage of digital versus analogue high-speed films is the possibility to automatically "digitize" defined markers. The contrast and brightness of the sequences can be modulated in wide ranges; even at very high frame rates, a film can therefore be shot at relatively low light intensity. The construction and sensitivity of modern charge-coupled device (CCD) detectors allow filming with relatively high resolution at over 10 000 fr/s. The only remaining limiting factor for increasing the frame rate is the light level to which the animals are tolerant and still behave "normally" during the experiments. The present study uses film sequences from feeding events and defensive responses in animals, but also films of pistol shots, to demonstrate that choosing an adequate frame rate is crucial for any kinematical analysis.