Nikon D4S review – Autofocus
Once again, the D4S employs a system used in the D4 – in this case, Advanced Multi-CAM 3500FX autofocus, which has 51 points and 3D tracking. Having used variations of this system on a number of different cameras, I had high expectations for the Nikon D4S, and it didn’t disappoint.
I took the D4S to photograph deer in a country park and found that, with the AF set to continuous and 3D tracking, the camera was able to comfortably shoot at a rate of 11fps and track a trotting deer, with all frames sharp and in focus. What is particularly impressive is that when you are in 51-point 3D tracking mode, you can see the AF point changing in the viewfinder as the camera shoots its 11fps burst.
More of a challenge than trotting deer were galloping horses heading down the finishing straight at Lingfield Park race course in Surrey. These provided an altogether tougher challenge for the D4S. From around 100m away from the finish line, I was able to use a 300mm lens and 3D tracking to identify a horse and track it as it got closer, firing a sequence of 11 images that were all in focus. As the horses got closer, I fired off a second burst; on this occasion, the 3D tracking jumped from one horse to another halfway through the sequence. This was a challenging test for the camera, and using centre spot AF rather than 3D tracking, or limiting the 3D tracking to 11 points rather than 51, or changing the speed of the 3D tracking, can all resolve this issue. In fact, the sheer variety of ways in which the AF can be set up means that you have to spend time working out how best to use the options available.
One of these options is the new group-optimised AF, which uses a group of five points and switches between them when focusing. This is a great option when photographing at an event, for example, where a subject will always remain in roughly the same point in the frame.
Images: In less than 0.5sec the D4S was able to take this sequence of images, and make slight changes to the focus each time to ensure sharp images
