25 Feb 2008 22:20:12
When the sun shines (too) bright

Remember the 1990 Breeder's Cup sprint with Dayjur jumping shadows not
once, but twice to lose the race by half a length when he had it won?

Horses have a very hard time when the brightness differential between
the rail and the middle of the track is so stark. They often drop back
on their instincts thinking it represents a object in their path.

Think that is bad? For all you photographers out there, the rail can
often be 4 to 5 F stops brighter than the middle of the track, making an
accurate photo finish a real challenge. Not only that, but as the sun
moves low in the Winter sky, that brightness differential is ever changing.

Since sunlight carries a yellow cast, it requires one, often TWO deep
blue filters to balance the exposure to make out a close finish between
a horse right on the rail and one further out in the track. Also,
because there is reflected light coming off the racing surface, a gray,
neutral density filter is required to evenly shut off a lot of extra
light. Also, one does not want a blue image, so each time the exposure
changes, one has to white balance the images.

Add some meandering clouds to the equation, and one has to be very quick
on the draw adding or pulling out filters to get the exposure required
to differentiate a close finish.

Luckily the computer has various editing settings and split screen
imaging controls to bring back under or overexposed parts of the photo.
Sometimes, even on blow ups, the dark background of the racing surface
is hard to differentiate from the brown of a horse's nose.

I vote for cloudy overcast days with no harsh shadows. It makes life a
lot easier.