KILLER AF-SYSTEM

One of the most interesting changes with the Nikon D5 camera is related to the AF-system. At first glance it looks similar to the D4S, but it certainly has some important modifications and new features. 153 active AF points is one of the biggest improvements in the Nikon D5 AF-system (D4S had 51 AF points), not only because of more active AF-points, but also more (99) high quality (cross sensor) AF-points. The AF point structure has also changed with more cross sensor AF-points in the edges in the frame – not only in the center. When using lenses with maximum aperture f/4.0, 55 out of 153 AF points are selectable. With maximum aperture f/5.6 still 55 AF points are selectable, and with f/8.0 9 AF points are selectable. During my testing I could feel the difference best when shooting with big telephoto lenses (400/2.8 and 600/4.0) and with fast moving subjects – like the grizzley bear below. The AF-system worked impressively fast – not only in the center of the frame, with 99 active cross section AF points and 55 selectable. I also noticed a higher percentage of images sharp during longer bursts, than I’ve experienced before.

When adding a 1.4X extender to my 600/4.0 lens the AF-system still worked very fast, which was something I appreciated a lot. The AF system did not only work faster, but also more reliable than earlier, and I still had 55 (44 cross section) selectable AF points available. Since the combination with long lenses and 1.4X tele extenders results in very high image quality, this is good news for all long lens shooters. In the image below I photographed a Silver grebe bouncing up and down in the waves, which is challenging for most AF-systems. With the Nikon D5 camera it was not too difficult to get the bird sharp where I wanted. Even with the subject located in the corner (like the Gentoo penguin below) it was easy to get it sharp without forcing it to be in the center.

I have never photographed a lot with long lenses and 2.0X extenders, because the AF-system is usually working too slow and the images are too blurry. With the Nikon D5 this is about to change. With 15 active AF points (5 cross section) where 9 are selectable, I had much better AF control and AF speed than ever experienced before. This is a big upgrade, and made photographing with 600/4.0 lens and 2.0X extender even in low light conditions possible. The image below is an example of a very low light situation with ISO 25 600 and 600/4.0 + 2.0X extender. With the D4S I would not even think about trying to photograph in situations like this with this 2.0X big lens combo.

Dynamic AF-Range in the Nikon D5 camera has now increased from d9, d21 and d51 (in D4S), to d25, d72 and d153. This was one of the most important upgrades for me to test – how does the d153 AF-setting perform in action photography? So I used this d153 AF setting for many different situations, even where I would normally choose the Group-area AF setting. For me the Group-area AF setting has worked best when shooting action with the D4S camera, but the d153 is about to change this. With a clean and not too disturbing background the d153 worked amazingly. The AF followed the subject even when it was far away from center, like the bird below. With the d153 activated it is easier to follow fast moving subjects than I have been used to with D4S (and previous pro cameras).

The biggest challenge for the AF-system is still situations with reflections and / or high contrasts in the background. The d153 have some problems following low contrast subjects, like in the image below with an Arctic tern in flight in front of reflections in the water. In these situations Group-area AF was slightly better than d153.

Focus tracking with Lock ON has now changed from a single selector to 2 sliders. The upper slider is similar to the menu selections in the D4S camera, but now you also have a slider for Subject motion – Erratic to Steady. This is a way to tell the AF-system if you are following steady moving subjects (like a car) or erratic movements (like a bat or bird). These settings work well in combination with the d153 AF-setting. Below is 2 images with active Focus tracking with Lock On (set to “long”)

The Nikon D5 AF-system is also improved for low light photography to EV -4 (EV -2 on D4S). In real life photography low light sensitivity will differ between the lenses you are using. When I was shooting with 600mm f/4.0 late in the evening I came to a point where it was not possible for the camera to get my subject in focus any longer, as shown in the image below. I changed to the 400mm f/2.8 lens and could shoot 7 more minutes before it was too dark also with this lens. The low light EV performance in the Nikon D5 camera is very impressive, and opens for new possibilities when it’s very dark.

After 50 000 exposures with the Nikon D5 cameras in difficult conditions, I’m very satisfied with the AF-performance. Somebody has talked about a new “Nikon D5 Killer AF-system”, and it’s difficult not to agree. I experienced the biggest improvements when using long lenses in low light conditions.