Thanks for the info. I neglected to look at the links in your previous post. I would have thought by now they’d have a series of very high speed normal pictures to resolve this, but this is probably a more practical method, and through it’s traditional use less controversial (because every little change at the Olympics is a controversy).
And I think I’d have a problem with actual clown shoes being an unfair advantage in the race
The “scanning” photofinish camera is really the only practical method, or at least certainly by far the best. Rather than having a series of high-speed pictures, and having to look at different pictures as each person crosses the line, with a photo-finish camera, the exact moment that every athlete crosses the line is all there on one photograph - and you can read the exact finishing time for each runner, down to the thousandth of a second, off the time-scale at the bottom. In the triathlon pic, for example, the vertical red lines show the times were about 1:59:48.609 and 1:59:48.618. Less than one hundredth of a second after almost two hours of racing. (And it would have been easier to get the lines in exactly the right place without that bloody great ribbon, of course!)
It’s a pretty neat invention, really.
So, if I’m understanding it right (based on some other articles) these photo finish cameras are basically like a specialized movie camera but the frames are displayed over a horizontal dimension, rather than as a sequence of images, correct?
Curse you SD, for making me figure out yet another thing.
Yep. You could imagine it as taking a series of very tall thin photos of the finish line and pasting them one after the other from right to left to make one big image.
A bizarre consequence of this is that it doesn’t matter which direction the runners cross the line in - they will always appear in the same orientation on the photo, as demonstrated by the photo of the runner and the cyclist halfway down this page. That messed with my head, but if you think about how the image is assembled, it starts to make sense. Note the shadows, too.
In this instance, the sun was shining from the left. So the runner’s shadow is pointing right as it should be: first his shadow crossed the line, then his right leg and left hand, then his body and finally his trailing hand. After he crossed the line, the cyclist’s front wheel crossed - from the right - then the rest of his bike and finally his shadow (because it was behind his direction of movement, whereas the runner’s shadow was ahead of his direction of movement).
Is there a particular reason that the standard for finishing involves the torso? It strikes me from the photo finishes I’ve seen that it would be easier to change the rule to allow any body part to cross the line. In both the triathlon and the 100m at the Olympic trials, the photos distinctly show a winner by that standard.
Before finish line cameras/auto-timimg systems, it was the good old human eyeball. Far easier to focus on one spot(chest usually) rather than trying to spot a hand or foot in the flurry of motion at the finish.
And also because it would invalidate all previous world records, which were set by the torso. For example, in Usain Bolt’s 9.58 second 100m record run, the photofinish shows that his foot crossed the line at 9.53 seconds. If the rules were changed, runners would dive for the line with outstretched arms and maybe gain 0.1 seconds or more, making comparisons with past performances impossible.