- Ed Dozier
Nikon Z9 AutoFocus Area Mode Speed Measurements
The Nikon Z9 has quickly gained a reputation for its focusing prowess. This reputation centers around its ‘stickiness’ and accuracy. I couldn’t find any useful data about how its various focus area modes compare for actual focusing speed.
I wanted to find out if there were any significant focus speed advantages or disadvantages when changing focus-area modes. I’m using the firmware version 2.1 and testing with the Nikkor 500mm PF f/5.6 lens. This is of course an F-mount lens, so I’m using the FTZ-II adapter.
Nikon Z9 with 500mm f/5.6 PF
I have assigned 4 different focus-area modes to 4 different buttons, since I found out on the first day of Z9 shooting that one mode definitely won’t suffice. I always leave my focus on AF-C.
My camera is set to “automatic subject detection”, which I think means that it will first try ‘people’, then switch to ‘animal’, and finally switch to ‘vehicle’.
My testing involves setting the lens on minimum focus and then having the camera focus on a target (a high-contrast distant tree) at ‘infinity’. For all tests, the same sunny conditions were used, as well as the same high-contrast distant target. In real life, you’d almost never have your lens at minimum focus distance and then focus on infinity; realistic focus times will be much faster than what my test numbers indicate.
I used 120 fps slow-motion video to record the 500mm lens focus scale during the test. To time the focus, all I have to do is count the frames to go from the start of focus scale motion to the end of motion. Each frame is 1/120 or 0.0083 seconds.
As an added benefit, the video will clearly record if there are any hiccups or stutters while focusing. This stuff can happen faster than your eye can track.
For comparison to the Z9 camera, my Nikon D500 focus speed with this 500mm lens is typically 0.308 seconds. The D500 focus system is supposed to be the same as the D5 model, and it seems to be just a hair faster than the D850 focus system.
This is my favorite focus-tracking mode. In most situations, the focus box will really stick to the selected subject, no matter how it moves around the frame. It works for more than just eyes. I assigned this mode to the AF-ON button (I never use the shutter button to focus).
Focus typically took 41 frames, or 0.342 seconds. A couple of times, I got 39 frames, or 0.325 seconds. This is about 5 to 10% slower than the D500. In actual practice, you should consider this contest to be a tie with the D500; you’d never notice the difference.
I assigned this mode to my fn1 button. For stuff with eyes, this mode works well most of the time. Sometimes this mode totally outperforms 3D-tracking, and often it’s unpredictable when those occasions are going to be.
Focus took 42 frames, or 0.350 seconds. A bit slower, but not really enough to perceive the difference.
This is a ‘dumb’ mode, used for when the camera insists on tracking the wrong thing with the fancy AI modes. This is also the primary mode I’d be using with my D500 camera. I assign this to my fn2 button.
Focus took 41 frames, or 0.342 seconds.
Use this when you need precision, and the subject isn’t moving. I assign this to my fn3 button. This is another “dumb” mode with no AI behind it.
Focus took 40 frames, or 0.333 seconds. This seems to be the fastest mode, but not enough to tell the difference from the others.
I didn’t see any focus-stutter in any of the modes. If I switched to low-contrast targets, I could get any of the modes to focus-stutter a bit, although nothing that you could notice with the naked eye until really dim conditions.
It appears that you needn’t worry about which focus mode you select causing a slowdown. The Z9 is really fast at focus speed, period. It was quite unexpected, however to see that my D500 had a slight edge at raw focus speed, although it’s no competition with the Z9 when it comes to either focus precision or ‘stickiness’ at subject tracking.
Don’t worry about the F-mount lenses being slow to focus, compared to the pro-level DSLRs. I seriously doubt that you could notice any difference. I bet you will notice a difference in focus precision, compared to DSLRs; the Z9 just nails focus wherever the focus sensor is aimed.