Last year, Swedish car manufacturer Volvo ran into a tricky problem with their driverless car technology. Although it could correctly identify and predict the movement of pedestrians and wildlife such as deer and moose, it was
flummoxed by kangaroos. To start with, a stationary kangaroo standing upright on the side of a road is a completely different shape from a hopping kangaroo. Second, when in mid-air during a hop, the software cannot accurately judge its distance; it thinks it is further away than it really is because it assumes it is on the ground. Thirdly, kangaroos can and do change direction almost instantly. These were challenges that defeated the resourceful Swedes.
Kangaroos are different shapes when they stand or hop
Pentax also struggles with the large macropods. No, I don't mean motion prediction; even a sloth defeats Pentax in that game. I refer to auto-focus on stationary 'roos. I have taken hundreds of kangaroo shots in the wild, many of them of animals just standing and grazing or looking around. But only a small proportion are in sharp focus, far smaller than the almost 100% I get with other subjects, including stationary birds. This is despite very careful AF on my part.
On the weekend I was out for a walk with the K1 and DFA 150-450 and came across a small mob of Eastern Greys grazing in the late afternoon.
Here is a close crop from another shot.
Although the full shot doesn't look too bad, this crop obviously fails to satisfy the discerning pixel-peeper. I think there are two reasons. First, there is something about kangaroo fur that doesn't allow the Pentax AF algorithm to judge focus. Second, even if I try to focus on the eyes (a successful strategy with humans and many animals, but difficult handheld with the K1+DFA 150-450 in the wild), it doesn't always work because kangaroos' eyes are almost completely black and featureless.
Nevertheless, with about 90 shots in all, I got 10 or 15 worth keeping. But this is well below my standard keeper-rate.
What do others think? Do certain animals cause you AF problems? And do others have particular problems with kangaroos?
Last edited by Paul the Sunman; 01-21-2018 at 02:44 PM.