I recently made the decision to move almost exclusively over to all Nikon FX bodies. For those not familiar, FX is the designation Nikon makes between their so-called Full Frame sensors and their DX 1.5X cropped APS sensors. My main reason for switching from the DX sensor cameras, the D300 and D7000 bodies I’ve used for the past 5-6 years, is due to the tremendous low light capabilities Nikon’s FX cameras offer. But that’s a different story.
In this post I want to cover my experience with an equally important feature I rely on heavily – Predictive Focus Tracking. I specify Predictive Focus Tracking since virtually any camera made today produces quality autofocus images of subjects not moving. But when it comes to action, not all cameras are created equal, and that’s where Predictive Focus Tracking comes in.
Annie on a dead run for the tennis ball.
The three cameras I’m currently using and the ones tested for Predictive Focus Tracking were the D600, D800, and Nikon’s top of the line D4. I’ve seen many AF tests offered on other sites but I’ve never seen the tests performed using the techniques I use. My real world approach is easy for photographers to try themselves and more applicable to nature and action-oriented shooters.
So what is my technique? It’s pretty simple. First I recruit a fast dog, preferably a younger lab or retriever. I’m only interested in the ones that will offer to escort their ball throwing master, and I request they bring their favorite fetching toy, which is usually a tennis ball. That’s it. The key to getting the best results is lining the pooch up AND getting the master to throw the ball in a straight line. I find getting the dog lined up is the easier of the two requirements. In fact, during this most recent test, my good friend Bill Buckley, world-renowned hook and bullet shooter, was almost useless as a thrower. But his well trained golden lab Annie persevered, didn’t leave until she was told, and did her best to correct her crooked line while going after a poorly thrown ball. Annie and I held a meeting after the shoot and decided even though Bill was throwing like a girl we were able to pull off a sufficient test.
You’ll see in the images I’ve included for review, Bill is off in the distance, about 30-40 yards. Annie sits by his side, labrador enthusiasm pulsing through her veins as her master does a few circle swings warming his aging throwing arm. He eventually fires and Annie comes sprinting towards the camera. All jokes aside, the key to this test is to get your camera on the fast moving dog heading straight into the viewfinder. This is where the camera either succeeds or fails. I shoot as many frames as possible on each throw, doing my best to keep the center focus sensor on the dog’s head or chest. With an animal moving at this speed it’s difficult to just keep them in your sights, so I don’t try for any composition other than to keep the AF sensor on the animal.
The camera was set to 9 Point Dynamic area-AF. Motor drive was set to Continues High and the AF sensor was set to the dead center, middle square. These are the settings that should give me the fastest Predictive Focus Tracking possible. Nikon has numerous AF-Area Mode settings. AF-Area Mode is selected via a little mini lever on the front lower left side of the lens flange. This little mini lever turns the AF from On to Manual. The inside middle of that lever there is a button that you push to switch between AF options which appear on the top or rear LCD. Those AF options are:
- Single Point-AF
- Dynamic Area-AF
-9 point dynamic-area AF
-21 point dynamic-area AF
-51 point dynamic-area AF
- 3D Tracking
- Auto-area AF
These are all listed in the Nikon manuals and you can read what each one does there. For this test I used the 9 Point Dynamic-area AF. The concept behind 9 Point Dynamic Area-AF is to give you a small group of 9 AF points that start with one single AF Point but switch to the other AF Points depending on if the subject moves out of the single point originally chosen. This gives you a larger point to stay on the target.
Also, it should be noted that all images were shot at the 200-400mm’s maximum aperture which is F/4. Why is this important? By shooting at wide open or F/4 there is no benefit from a smaller aperture giving depth of field advantages to the image. All images have to be in focus without relying on depth of field from a smaller aperture.
Still charging towards the camera.
That’s all there is to producing this test. I’ve listed the results below which were based on me reviewing all of the photos from each camera in Apple’s Aperture. I would select the image and review it at 100% to look for critical sharpness. Sometimes the head may be slightly out of focus but the chest of the dog was in focus. If the sensor was shown to be on the chest then I considered the frame focussed properly. Remember, I wasn’t even trying to keep the dog’s head in the upper third of the frame as you might normally do if she was just standing there. Annie was fast enough for me to just be happy to keep her in the viewfinder.
I’ve broken the results into three categories.
5 Stars = Critically Sharp, or as some would say “wicked sharp” or “killer sharp.” I prefer Critically Sharp 🙂
3 Stars = Just slightly out of focus. May even be focused enough to be usable for some people.
1 Star = Completely out of focus.
Unfortunately, the web does not provide the quality needed for reviewing these images as I get on my computer. That being the case, you’ll just have to trust my numbers. But believe me they are accurate. Let me know if you have any questions. I’m happy to hear your thoughts.
Predictive Focus Tracking Results – click on the links below to see results.
D4 – 156 Total
5 Runs to camera
1 Star-36
3 Star-11
5 Star-109
D800 – Total 155
6 Runs to Camera
1 Star-40
3 Star-13
5 Star- 102
D600 – Total 93
5-Runs to Camera
1 Star-28
3 Star-15
5 Star-50
As you can see by the numbers, the D4 did the very best which is to be expected since it’s by far the most expensive body. The D800 did better than I was expecting and the D600 did an admirable job being the least expensive camera of the group. From what I’ve seen in the past, these numbers are considerably better than I got with earlier Nikon‘s in Predictive AF. Even though there are a fair number of completely out of focus frames, you have to keep in mind that there are few things we shoot that are as fast as a lab coming straight at the camera at that close of a distance. Additionally, dogs run erratically which makes the test even more difficult. I’ve never tried it, but my guess is these cameras would all have higher numbers of critically sharp images if you were shooting a race car at 200mph. Even though the car would be faster than a lab, the line it takes is consistent and the distance from the camera is further out. Overall a lab is a tough subject to nail down.