Canon 1D Mark III Review – AF Part 3, AI Servo mode, Cloudy Conditions

Issues reported with the Canon 1D Mark III’s AF system when
in cloudy or less-than-bright-sunlight conditions have been far fewer. From my
own experience, I’ve found this to be true also. In outdoor conditions which
did not fall under direct sunlight, I’ve found the hit rate to be naturally higher
when wide open and close to perfect when stopped down. I have
two sequences to provide below. The first is a pretty boring example but
served for the purpose of illustration.

Sequence 1 – First illustration of AI servo performance in cloudy conditions

I shot this sequence with in overcast conditions from an
flyover bridge. It was with the 200mm f/2.8 shot wide open. The shutter speed
was about 1/800 and ISO 500. Using the center point focus selection, I simply
tracked the subject over a period of about 4 seconds for a total of 40 images. The
first image in the sequence was this:

The last image in the sequence was this:

As the entire sequence is 40 images and it’s of a subject that barely changes, I won’t actually post the entire set. Instead I’ll summarise my findings. From this sequence, the statistics were as follows:

• 40 images
• 34 of the 40 were sharp (85%)
• An additional 2 were "OK" (acceptably sharp) (5%)l
• A total of 4 images were unacceptably sharp (10%)

So that’s 90% of images which were acceptably sharp.

Below is a typical example of what I consider to be a sharp image. This is representative of the other 85 – 90%. The crop is 100% and no changes other than a slight unsharp mask.

In contrast, find below one of the images that was unacceptably sharp. There were four of those out of the set which showed similar characteristics and were not due to operation or human error.

Essentially what happens there is that on a sequence of long images, sometimes the AF system loses the focus and takes an image or two to recover. I found this performance (90% good) to be fairly representative of shooting under these conditions. Unlike in sunny conditions when shooting wide open, I found the appearance of frames like this to be rarer in a sequence rather than the expecting to see them.

Note that I reshot these scene several times while stopped down to F5.0 or so and on all occasions, found that I had a minimum of 95% sharp rate (in most cases 100%).

Sequence 2 – Second illustration of AI servo performance in cloudy conditions

For this sequence, I took a trip out to a local wakeboarding center. The conditions were overcast and it was pouring with rain. I was shooting from a protected area, but having to shoot through large amounts of falling water so from a distance, that muddied things a little but you’ll get my point.

I wanted to include this sample as it includes another real world example which consists of shooting something far more difficult and complex than a man on a bike or a runner moving directly towards the camera.

The scene is fairly self explanatory from the first and last frames. These are are given below which mark the start and finish of a 13 frame sequence.

The first frame was:

The last frame was:

Due to the fairly low light from the overcast conditions, I had to shoot at ISO 1000 to get enough shutter speed to stop the action (1/1350s). As in the previous example, I had already stopped down (to f5) – although this was more to reduce user error than compensate for anything the camera would do incorrectly.

Below is the sequence of 100% crops with auto-contrast applied (to account for the lack of contrast from the sheet of rain that lies between me and the wakeboarder) and a minor unsharp mask. Rather than provide these in a grid as I did previously, I’m actually going to provide a brief comment on each one as it requires some brief explanation and discussion.

Frame 1 – this was the first frame shot and the AF system immediately locked on successfully to the target. You can see the rain interfering somewhat with the sharpness, but this is a successfully focused image.

Frames 2 and 3 and 4 – similar to the first frame, these are all sharp in focus. Both myself and the camera have done a good job of tracking the subject here. We’re 100% so far.

Frame 5 – this is the camera’s first infraction. Similar to the example I gave in the previous example, it’s just one of those times when the camera’s AF system gets confused and misses the target quickly. One frame in 13 is definitely acceptable to be out of focus on a fast moving subject, the question now is how quickly the camera recovers.

Frame 6 – the next frame, the camera recovers perfectly and delivers a sharp in focus image. You can see the rider is moving at fast speed as he’s closed in considerably on my position and as there is less rain I’m shooting through now, the image is sharper. So far I’m doing a good job of tracking the wakeboarder also.

Frames 7 and 8 and 9 – these are interesting. When you first look at them, you might think that the camera’s AF system has missed the subject here. However, if you look closer, you can actually see it’s the user, in this case me, at fault here. What the wakeboarder is doing is that he has suddenly leaned into his turn to generate tension for the jump he’s about to pull and I’ve unsuccessfully tracked him. With the center focus point I’ve steered off subject enough to fool the camera into thinking that the background water is the subject. It’s clear that this is the case as you can actually see the center of the frame is in focus. Had I turned on one of the custom settings to enable AF assist points (or to desensitise the AF system), this probably wouldn’t have happened but in some ways, I think it’s actually a more interesting case like this. Here you can actually see the importance user skill plays in the ability to get in focus shots. For me, here the AF system has done its job correctly. The real question now is how quickly the AF can recover once I start to correctly aim the focus point again.

Frame 10 – this frame answers the previous question. As soon as I manage to correctly position the center focus point back over the wakeboarder, the AF system instantly snaps back into focus delivering a sharp image.

Frame 11 and 12 and 13 – the final three shots again show the AF system doing its job. Three final sharp images. And remember, these are ISO 1000.

So the camera delivered 9 out of 13 sharp shots of the wakeboarder, but the truth is that it really delivered 12 out of 13 sharp shots as 3 of them were my fault. The recovery of the AF system was excellent in the case of frame 10 and I was extremely impressed with how it handled the situation.

If you’re wondering what happened next by the way, you can look for the final images of the jumps in the Image Quality section. In summary however, I can tell you that this particular wakeboarder made a total of 4 runs around the lake producing spectacular jumps on each of them that I attempted to photograph. In every case, through my own tracking and excellent performance by the camera, I managed to get a sharp, well focused "money shot" on each of his runs, capturing him at the peak of his elevation. Excellent.

Conclusion
The Canon 1D Mark III performs at a very high level under cloudy or overcast conditions. Shooting wide open, I am able to get it to produce a rate of around 90% sharp shots. Stopping down slightly, that success rate climbs even higher and even on far more challenging subjects, when the user does his / her job correctly, the camera produces fantastic results. With the deeper buffer and increased shutter speed that the 10fps per second brings, I find it almost impossible to believe that a similarly skilled Canon 1D Mark IIn user is going to be able to produce a greater number in focus images under these conditions.