Autofocus and performance

Out of camera JPEG.
ISO 11400 | 1/500 sec | F4 | Nikon 300mm F4 E
Photo: Dan Bracaglia

The Nikon D780 combines two AF systems into one camera: one for shooting through the finder and one for using live view. By and large both systems work well, but there are some key differences between the two.

Key takeaways:

  • Excellent AF-C performance whether shooting through the finder or in live view
  • Face detect works well through the finder and in live view
  • Accurate eye detect in live view (not available through the finder)
  • Subject tracking in live view is cumbersome to use and unreliable compared to subject tracking through the finder
  • Different AF area modes between finder and live view shooting can be confusing
  • Live view AF offers more points and greater coverage than through the finder
  • 7 fps burst with AF when shooting through the finder, 12 fps burst with AF in live view (albeit with significant rolling shutter and 12-bit Raw)
  • Impressive 100 frame buffer depth with minimal slow-down

AF overview

When shooting in live view (right), compared to through the finder (left), users get more points and greater coverage at the cost of a less-reliable AF tracking experience. Image courtesy Nikon.

When shooting with the optical finder, the D780's uses the same 51-point hybrid AF system as its predecessor, the Nikon D750, but with updated algorithms and a higher resolution metering sensor for subject tracking, both borrowed from the Nikon D5. All points are sensitive to a –3 EV. Relative to peers and to its own live view AF system, the coverage of AF points across the frame feels somewhat limiting.

For live view, the D780 uses the same hybrid AF system as the Nikon Z6 with 273 phase-detect points, an absolutely huge improvement over the D750's contrast detect-only live view. All points are sensitive down to a claimed –5 EV (when used with an F1.4 lens).

We've already gone into great detail about how differently Nikon's DSLR and mirrorless autofocus systems behave and operate (hint, quite differently), and now we've got both in one camera! For the sake of this write-up, we'll concentrate on how they perform in comparison to one another in our standard AF tests. But for a quick refresher, the video below explains how the Z7 (live view) and DSLR (finder) AF systems differ. Pay attention to the differences in AF area modes, particularly when it comes to subject tracking.

AF performance

Note: All AF testing was done with the camera set to its top burst rate - 7 fps through the finder and 12 fps in live view - using default AF sensitivity settings and face/eye detection turned off. Images were shot using the Nikon 70-200 F2.8 ED VR II lens at F2.8 and at 200mm (tripod-mounted). The lens was focus adjusted using Nikon's 'AF Fine Tune' feature prior to testing the through the finder AF system.

AF speed - through the finder

Our first bike test assesses how well the camera can maintain focus on a rapidly approaching subject using a single focus point.

As we've come to expect from this tried and true 51-point AF system, the D780 nearly aces our first test with flying colors. The above example is from the middle of the run and is representative of the whole run: the majority of images are critically sharp, with a handful just slightly off the intended plane of focus, but still usable.

AF speed - live view

Next we ran the same test, but this time using a single AF point in live view. Note: To unlock the D780's 12 fps burst in live view turn on 'Silent live view photography' (last option in the 'Shooting' menu). This comes at the cost of rather severe rolling shutter if you're shooting fast-paced action.

Similar to our results when shooting through the finder, the D780 absolutely nails this test, even with the burst rate nearly doubled.

AF subject tracking - through the finder

The camera can clearly maintain focus on an approaching subject with ease, whether shooting through the finder or in live view, so it's time to up the ante. Our next test examines how well it can both maintain focus on an approaching subject while also having to recognize the subject and track it around the frame. We used the camera's '3D-Tracking' AF-C mode to engage subject tracking.

It's worth noting: Because the AF coverage is less wide than live view AF, we instructed our cyclist to stay a bit more central in the frame when testing this mode.

The results here are pretty solid: the vast majority of images are critically sharp or sharp enough for standard use. However there are some instances of the camera completely falling behind focus - mostly at turns where the rate of approach changes - leading to throw-away shots, unlike in our first test. The good news is tracking always seems to catch back up, usually within a frame or two. It's also worth noting, increasing the responsiveness of 'Focus tracking with lock-on' (a3 in the Custom Settings menu) may further improve the hit rate.

These results are again, about what we've come to expect from this AF system. That said, any improvements resulting from the inclusion of the D5's tracking algorithms and metering sensor are imperceptible, at least in the case of this test.

AF subject tracking - live view

The results here are less encouraging: Live view tracking at 12 fps is all over the place with the camera seemingly unable to keep focus on our subject for multiple frames at a time, only to catch back up, then lose the subject all over again.

The experience of using tracking in live view also leaves something to be desired: first, engaging subject tracking is more cumbersome than when shooting through the finder as there is no dedicated live view tracking mode. To track, you have to use the camera's Auto area mode and either tap a subject using the screen or press the OK button to bring up an AF point, before focus can be initiated. To switch subjects, you'll have to press OK again, or tap your new subject on the screen; either method makes it slower to switch subjects compared to '3D-Tracking' mode when shooting through the finder.

Furthermore, the AF box on the back of the LCD did not always move along with our subject, even though the camera was clearly attempting to follow and maintain focus.

It's worth noting that taking the camera out of Silent live view and shooting at the standard maximum live view burst rate of 7 fps (using the mechanical shutter) led to a modest improvement in the hit rate. But the number of keepers is still nowhere near what the Z6 managed in this same test at 5.5 fps.

Face and eye detection

When shooting through the finder, the D780 offers face detection, on by default in the camera's 'Auto' and '3D-tracking' AF area modes. In use, it does a great job finding the nearest or largest faces in Auto mode, as well as prioritizing faces near your selected AF point in 3D-tracking mode. It even aims for the upper third of the face, around where eyes are generally located.

Face detection paired with 3D-tracking is a very versatile way of shooting the D780: when you have multiple people in the scene, simply place the AF point over your desired subject, initiate AF, then recompose freely and the camera will focus on (roughly) the eyes of that subject. You can even be a bit sloppy with your initial AF point placement: as long as the AF point is near a face when you initiate focus, the camera will automatically select AF points near the eyes. This 'sloppiness' allows you to work faster, and since 3D-tracking resets instantly when you release the shutter button, it's quick to re-aim and change subjects.

When shooting in live view the D780 offers face and eye detection, on by default when using 'Auto-area AF mode'. Its behavior mimics that of the Nikon Z6 (see video above and an in-depth article here). In action, it's fairly reliable and tends to focus on the eye or face of the largest subject in the frame. When multiple faces are detected, users can switch between them using the D-pad or by tapping the desired face on the screen. When using the latter method, the camera will occasionally switch into its standard subject tracking mode, which requires an additional button press/screen tap to exit.

Overall we have mixed feelings about the implementation: while eye detection is very useful, the camera has a tendency to front-focus, and choosing or switching between faces isn't as quick as the 'aim-half-press-recompose' method the camera's 3D-tracking mode provides when shooting through the finder.


Performance

When shooting through the finder, the D780 gain 0.5 fps over its predecessor giving is a respectable maximum burst rate of 7 fps: the maximum number of frames per burst caps out at 100. With a fast enough card, the D780 can fire off all 100 frames in a burst without slowing down as long as your quality is set to JPEG or Raw only (it will slow down around 25 frames in if you're saving both).

In live view the D780 can either shoot at its standard max burst rate of 7 fps, using the mechanical shutter, or 12 fps in 'Silent live view' using the e-shutter (12-bit Raw only). Regardless which you choose, the D780 is capable of firing off 100 JPEGs (high-est quality) without slowing down. However, if you're shooting Raw files, the burst will start to slow at about 55 frames in - 25 frames if you're shooting Raw+JPEG.