In a simplified form:
1. As the car approaches the camera position, the angular speed of the camera needs to increase exponentially along curve C1.
2. As the car leaves the camera position, the angular speed of the camera needs to decrease exponentially along curve C2.
3. Therefore, the angular speed must switch from exponentially increasing to exponentially decreasing at the instant the car passes the camera position at P (when the car is perpendicaluar to the camera).
4. Mathematically, at that instant, the required precision goes to infinity. By definition, no human can achieve infinite precision.
5. The camera operator will gradually diverge from the C1 curve before P and from the C2 curve after P. The error becomes more evident as the car approaches P and less evident as it leaves P.
origin of the problem
Screenfloat is very difficult for a human operator to overcome. In one particular type of shot, it is mathematically imposssible: panning shots of a fast moving target. The difficulty increases exponentially as zoom is applied.
The problem is illustrated below. The problem can be avoided or mitigated, in both cases to the detriment of the interest of the shot:
1. Avoiding panning shots, filming fast moving targets as they approach the camera in a direct line. These kind of shots negate the perception of speed by removing useful visual references for the viewer. The effect is aggravated when zooming out as the target approaches. This results in 2/3 of shots being frontal in typical motor-racing coverage.
2. Mitigating the extent of the screenfloat on a panning shot, by keeping a wide shot. This results in a panoramic image and a small representation of the target. This results in a car covering more than 1/3 of the TV screen in only 10% of typical motor-racing coverage.
The problem with Screenfloat
The most striking effect of Navicam™ is that it eliminates a phenomenon we have called "screenfloat". The effect is illustrated in the two videos on this page.
Screenfloat is doubly detrimental to image quality:
A. The erratic movement around the screen.
B. Image blur due to the poor of synchronisation between the movements of the camera and the target.
The two computer animations below visualise the effects of screenfloat and how it is eliminated with Navicam.
How we measure screenfloat
The trace on the image illustrates how the center of the car has moved around on the screen during a panning shot of 5sec. The inevitable result is a blurred main subject and an irritating viewer experience. This is not an exception: Captimax has documented hundreds of scenes from top broadcasters.
Restricting the cameraman's margin of manoeuver
By isolating the trace, the extent of the problem becomes obvious. The trace also illustrates the cameraman's defensive action: had he zoomed in closer, the subject would have left the screen up to seven times, at the top, bottom, right and left. The equivalent trace from a Navicam controlled shot hardly strays from the centre of the screen.