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01-21-2018, 01:45 PM - 2 Likes   #1
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The technological challenge of kangaroos

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.
01-21-2018, 02:26 PM - 3 Likes   #2
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QuoteOriginally posted by Paul the Sunman Quote
The technological challenge of kangaroos
Well least Volvo shoudn't have too many problems here in Scotland then.
01-21-2018, 02:39 PM   #3
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Interesting.

I would have to say that photographing kangaroos is not a common activity here in the Canadian wild. However, I've taken a few (long-distance) shots in a zoo with a 135mm FL; the two images that I've kept on my disk suffered from poor lighting and relatively small outlines of the 'roos, so I can't say whether the focus was seriously off.

I see what you mean by the eyes.

The only comparable native animal that I could compare is our white-tailed deer. The fur is similar is some respect, but I think the contrast is higher. The eyes are dark, but there is sufficient contrast around the eyes that I can usually get a sharp focus. Of course, the tail offers a perfect focus target!

01-21-2018, 02:39 PM - 3 Likes   #4
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QuoteOriginally posted by Kerrowdown Quote
Well least Volvo shoudn't have too many problems here in Scotland then.
I believe they're struggling with the Loch Ness Monster subroutine.

01-21-2018, 02:48 PM - 1 Like   #5
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QuoteOriginally posted by Paul the Sunman Quote
I believe they're struggling with the Loch Ness Monster subroutine.
That's only cos Volvo cars don't know how to drink whisky...
01-21-2018, 02:53 PM - 1 Like   #6
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QuoteOriginally posted by Paul the Sunman Quote
And do others have particular problems with kangaroos?
Yes, because I can AF on a kangaroos, I have to find one.

QuoteOriginally posted by Paul the Sunman Quote
Do certain animals cause you AF problems?
The problem is usually to be close so that there is a greater subject / background separation, that helps the AF to lock on the subject. For birds in flight or on a perch, that condition is often achieved because the ground is out of the frame. But for animals close to the ground, there is obviously an area of the frame where the subject and the background are in the same plane. Moving the camera closer to the ground helps increasing separation between the subject and the background, removing most of the ground from the frame.
01-21-2018, 03:08 PM   #7
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QuoteOriginally posted by biz-engineer Quote
Moving the camera closer to the ground helps increasing separation between the subject and the background, removing most of the ground from the frame.
I almost always use spot focus, so that shouldn't be an issue. Also, getting closer to skittish animals is not always possible.

01-21-2018, 03:27 PM - 1 Like   #8
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Well I kind of had the same issue near Tidbinbilla Nature Reserve (not too far from Canberra) a year ago. Heaps of kangaroos there.

However, I guess my humble K-70 and the 16-85mm lens were enough to beat Volvo on this occasion Even through the windshield of the car.

But ye, with the 55-300PLM I had lots which were similar to yours: fine when looking at the picture as a whole, but not so great as a crop. But I suppose the difference in lenses (150-450 vs 55-300), camera (K70 vs K1) and my relative inexperience were also part of the story.

The last one was actually a little scary. Quite a big one looked us straight in the eye, after running a bit towards us. I just had to quickly get a shot, wasn't ideal, but at least he didn't charge any further

But hey, cheer up! You get the chance to go back there and try again...I have to fly a bloody 16.000 km's for that :P
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01-21-2018, 03:41 PM - 1 Like   #9
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My biggest problem is not running over the mongrels, I don't drive a Volvo but I have the same program in my brain, I just keep killing them with my car, the smash repairer loves me. Now to do some tests on focusing on wombats, my 150-450 seems to struggle in the middle of the night focusing on them
01-21-2018, 04:31 PM - 2 Likes   #10
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I don't want to give the impression that I NEVER get focus. This is with the DFA* 70-200. Perhaps the light and contrast was better that day.

01-21-2018, 05:15 PM   #11
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QuoteOriginally posted by Paul the Sunman Quote
What do others think?
Yes. I thought it must have been my pathetic technique (no feedback needed) but it probably is something to do with the fur. They never seem to be really sharp. Black cats can also be a problem (as others have noted in an earlier thread) and that must be a contrast thing.

QuoteOriginally posted by Kerrowdown Quote
Well least Volvo shoudn't have too many problems here in Scotland then.
Not unless you are driving on Inchconnachan island in Loch Lomond. Or several other places around Scotland and England. Just Google "wallabies in Scotland". I had more trouble trying to edit the link than Volvo has with kangaroos. But don't get confused by the Rugby links that say "Wallabies mauled by Scotland" )

---------- Post added 01-22-18 at 10:30 AM ----------

QuoteOriginally posted by Paul the Sunman Quote
I don't want to give the impression that I NEVER get focus.

I can walk out the back gate (or even not get that far if one has found a way into the yard) and photograph wallabies at a range of 3-5 metres any day. On several occasions I have done this with a new lens and been disappointed with the results. I have put that down to me. But maybe I need to experiment a little and see if there is some technique that gives me more consistent results.
01-21-2018, 06:54 PM   #12
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Certainly close and more light will help.

These were taken with a K-x an DA 18-250 wide open at full stretch:

1/ Halls Gap zoo at about 5 metres cropped to head shot.

2/ Pambula Beach caravan park, wild roo but very used to people, distance about 2 metres. As you can see, the eyes arn't really black.
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01-21-2018, 07:18 PM   #13
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Ever try focusing on the ground in the same plane as the kangaroo and then moving back on him? Can it grab focus off the grass better?
01-21-2018, 08:41 PM   #14
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Ive got roos living close to me, i'll take the K-1 down the road and shoot it this arvo!
01-21-2018, 08:54 PM   #15
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QuoteOriginally posted by surfar Quote
i'll take the K-1 down the road and shoot it this arvo
if you are driving, (A)K47 might be a better bet.
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