A grizzly sprinting at 35 miles an hour from hundred feet away will sink its teeth into your expedition cargo pants in less than two seconds, giving you just enough time to engage the autofocus, select burst mode, and press the shutter. Depending on your reaction time and camera model, your closed ones may inherit six to ten pre-mortal frames that could be made into a very short viral video clip.
Reaction times for trained athletes vary from superfast 40 ms for Muhammad Ali’s fastest punches to 150 ms required to return a table tennis ball. Sprinters take 100-150 ms after registering the starting pistol to jump off the blocks.
As an action photographer, you might find it interesting that once an image hits the retina, it takes approximately 100 milliseconds before it consciously registers in the brain. Although the light travels much faster than sound, the human’s body visual system is actually slower than our audio system. When the light or an image hits our retina, the photons must be translated into a chemical signal that in turn must be converted into an electrical impulse that can be carried via the nerve fibres to visual cortex residing in the back portion of the brain. Visual cortex will process the input signal and split it into two entities – one processing the shape and identity of the object(s) we see, and the other decoding the location and motion of the object(s). These two streams are then combined into a final information block which is converted into conscious awareness. Lot of complex data manipulation and processing.
Neuroscientists have discovered another problem with the real-time watching. A simple assumption is that our visual system continuously monitors the surroundings and records it in “video camera” style. In reality, we are continuously scanning the entire scene and taking a quick sample from each location. The seamless connection and stitching of the entire scene is handled by the brain that combines the individual segments into an equivalent wide-screen scene that appears like a movie.
Typically, we perform about five such visual relocations per second with the minimum time of 200 milliseconds to shift our viewpoint. Then you add 300-400 milliseconds required to execute a cognitive decision and another 50 milliseconds to engage a motor command to be communicated by nerves to the finger on the shutter. All these activities add up to 500-600 milliseconds or half a second, which translates to several missed frames.
Case in point:
This past summer, I was photographing a whitewater kayak race. I used a 70-300mm zoom lens across its entire range, shooting at F8 in single frame mode. From my vantage point, I was able to follow the racers, set the continuous autofocus, and fire off one or multiple shots in each gate. Except one tricky spot on the river with a fast short drop followed by a haystack. I took a number of shots in that spot, some better than others. When I examined images on my computer screen, I came across the following shot:
I like this image, and it was a sheer luck capturing it. Surely, I wasn’t composing and focusing for the hand with paddle. Most likely, I noticed the racer just coming down the chute, focused on him and pressed the shutter. Let’s assume that in that particular drop the water moves at 15mph (24km/h), kayak moves relatively to the water at 5 mph (8km/h), so the resulting speed is 20mph (33km/h). If the distance from the top of the drop to the bottom is 5 ft (1.5m), moving at that speed, the kayak can cover 9m in a second, or 5 ft (1.5m) in 165 ms. This corresponds roughly with 100 ms required for a transmission of the image from the retina to the visual cortex, plus another 50 ms to press the shutter. And that explains the confluence of kayak being in the hole just with the hand and paddle visible behind the standing wave and click of the shutter in that very fortunate moment.
As the kayaker cleared the haystack, he was slowed down sufficiently, that I could easily focus on him in that position and make another exposure. If his speed in that moment was around 3-4 mph, he would cover in 165 ms only 1 ft (30cm) which didn’t pose any problem for locking the focus or sufficient depth of field at that distance.
Back to the grizzlies:
On August 24th, 2012, in Denali National Park, a grizzly attacked and killed a lone backpacker who was photographing the bear from just over 40 yards away. He took 26 pictures of the bear with his camera over a span of 7 1/2 minutes, but the bear seemed to take notice of him only for the last few seconds, according to National Park Service officials who based their assessment on satellite imagery and photo time stamps. The park service said that, based on “initial evidence,” authorities believe a bear attacked the backpacker by the river and dragged his body to a “food cache site” in a bushy area 100 to 150 yards from where the attack occurred.
Picture above taken by yours truly a few years ago in Denali from a safe distance, not too far away from the fatal site.
The hiker took the first bear shots with a wide angle. Then he zoomed in. The last five pictures, taken in a span of 13 seconds, show the bear lifting its head up, looking away from the camera, and then turning towards the photographer (did the hiker sneeze or yell at him?). The mauling probably occurred almost immediately after the last image.
“A bear could cover that distance before a person could react,” said the park ranger. The bear was estimated at 600 lbs (270 kg), big for Denali. It was a mature boar, at least 5 years old.
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