Nikon Z 28mm f/2.8 Focus Speed and Performance
The Nikon Z 28mm f/2.8 autofocuses quickly and almost silently, with very impressive accuracy both in the viewfinder and in live view. This is as much due to the camera as the lens, but it’s still great to see the trend continue on the 28mm f/2.8. The accuracy is fantastic and even better than a Nikon DSLR in live view (which itself is amazingly accurate).
Because of the f/2.8 maximum aperture, this lens is reasonably good at focusing in low-light conditions. Compared to an f/4 lens, for example, it can autofocus in conditions with half as much ambient light. For the photo below, I was able to autofocus on the building on the left without an issue – and this was with the Nikon Zfc instead of a low-light focusing champ like the Z9!
In terms of close-focusing capabilities, the Nikon Z 28mm f/2.8 has a decent maximum magnification of 1:5. This is a bit better than the 1:6 maximum magnification of the 40mm f/2 and allows you to fill the frame with something that’s approximately 18 cm / 7 inches wide. (On a DX camera like the Nikon Zfc, this improves to something about 12 cm / 4.6 inches wide.) It’s still not a macro lens by any stretch, but you can at least get some decent close-ups if your subject is large enough.
The Nikon Z 28mm f/2.8 has a moderate amount of barrel distortion, -2.39% by our tests. This amount is noticeable when photographing subjects with lots of straight lines, but it’s not extreme. Uncorrected, the distortion looks approximately like this:
This isn’t nearly as bad as many zoom lenses get, but it’s on the high side for a prime. By comparison, the Nikon Z 24mm f/1.8 S and 35mm f/1.8 S have -1.34% and -1.21% distortion respectively. Likewise, the Nikon Z 40mm f/2 – the most similar lens to the 28mm f/2.8 at the moment – has a mere -0.62% distortion.
Still, I wouldn’t worry about the distortion on the 28mm f/2.8. Distortion is one of the easiest optical problems to correct in post-processing with minimal side effects. In fact, if you use Adobe Lightroom, you’ll probably never see any distortion with the 28mm f/2.8 at all. That’s because the built-in distortion correction profile cannot be disabled with this lens.
Although I wish that Adobe would allow the profile to be disabled, it goes to show how distortion has changed from a major problem in the film days to a footnote with digital. You may still notice distortion on the 28mm f/2.8 if you use non-Adobe or non-Nikon software, but even then, it’s easy to correct.
In uncorrected images, the Nikon Z 28mm f/2.8 has moderately high levels of vignetting wide open, though it depends on your focusing distance. It’s worst at infinity focus and f/2.8, rising above 2 stops of exposure loss in the extreme corners. Here’s a full chart of vignetting levels:
This is fairly high vignetting, and unlike many lenses, it doesn’t improve much at narrower apertures. All the apertures from f/5.6 through f/16 have statistically indistinguishable levels of vignetting in our tests.
To me, any amount of vignetting over 2 stops is high enough to need correction on most photos. Anything over 1.5 stops is still relatively high. Under about 1 stop of vignetting is when it becomes negligible in my book.
By comparison, the Nikon Z 40mm f/2 maxes out at 1.95 stops of vignetting at f/2 and infinity focus. The Nikon Z 35mm f/1.8 S tops out at 1.83 stops, and the Nikon Z 24mm f/1.8 S at 1.94 stops. But this comparison is a bit deceiving, because all three of those lenses are capable of well under 1 stop of vignetting at various apertures and focusing distances, unlike the 28mm f/2.8. Here is the Nikon Z 24mm f/1.8 S’s chart, for example:
Keep in mind that Adobe Lightroom’s lens profiles for the Nikon Z 28mm f/2.8 directly read information from your in-camera vignetting reduction setting. If you want your photos from this lens to have full corrections by default in Lightroom, you need to turn the vignetting correction to “High” in the camera’s menu. This is true even if you’re shooting .NEF files. It’s not a big deal because you can always add or remove vignetting manually, but I recommend turning the in-camera corrections to “Medium” or “High” to minimize your post-production work with the 28mm f/2.8.
There is a moderate amount of chromatic aberration on the 28mm f/2.8 at every aperture. For a prime lens, it’s on the high side. Here’s the chart:
Anything under about one pixel is almost impossible to notice in real-world images, even with chromatic aberration correction turned off. The Nikon Z 28mm f/2.8 maxes out at 1.94 pixels of chromatic aberration, which is obviously above that threshold. By comparison, the Nikon Z 24mm f/1.8 S never goes above 0.65 pixels of CA; the Nikon Z 35mm f/1.8 S maxes out at 0.45 pixels; and even the Nikon Z 40mm f/2 stays under a pixel, with a maximum of 0.95.
Here’s a real-world crop to show the chromatic aberration on this lens in a worst-case scenario. The 100% crop below is a 930 x 620 pixel excerpt from the bottom right of a Nikon Z7 photo:
As you can see, some purple chromatic aberration is clear on high-contrast subjects, but it’s less obtrusive in lower-contrast areas of the crop. Most post-processing software can remove this level of chromatic aberration without too many side effects, but it’s still higher than I’d like.
Sunstars and Flare
The Nikon Z 28mm f/2.8 has fairly high levels of flare, including obtrusive red dot flare. I was hoping this lens would be a good choice for backlit situations due to the simple lens design with only nine elements, but unfortunately, that’s not the case. The lens has high levels of flare that become obtrusive when the sun is in the frame.
As for sunstars, the situation isn’t any better. For the life of me, I couldn’t get the Z 28mm f/2.8 to produce anything other than blob-like sunstars. The combination of weak sunstars and obtrusive flare led to bad results even on photos that I otherwise would have liked, such as this one:
Considering that 28mm lenses are wide enough to include the sun much of the time – not to mention the potential usefulness of this lens for travel photography in bright cities at night – I had hoped for a better result here.
Now the moment you’ve all been waiting for! Although lens sharpness doesn’t matter nearly as much as good technique, it’s true that a sharp lens helps. Corner sharpness especially can vary widely from lens to lens. How does the Nikon Z 28mm f/2.8 perform in this regard? It’s pretty good overall. Here’s the chart we measured in Imatest:
This chart shows how the lens starts relatively weak at f/2.8, then improves at f/4, especially in the center and corners. (The odd result of the weaker midframe at f/4 is due to field curvature, which is fairly high on this lens.) The strongest aperture is f/5.6, and the lens gradually weakens in sharpness as you march toward f/16 due to diffraction, as expected.
These numbers will be more relevant in context on the next page of this review, Sharpness Comparisons, but I’ll say for now that this is a good, though not excellent, result. It lags behind Nikon’s S-line prime lenses, as expected – and even some of their zooms like the Z 24-70mm f/2.8 S – but it’s still sharp. For the intended usage of travel photography, I’m not disappointed by this performance.
In terms of other sharpness issues, there’s some definite field curvature on this lens, as I mentioned a moment ago. You may not care too much about field curvature as a photographer; test charts exaggerate the issue relative to most three-dimensional subjects. However, if you’re shooting a subject where everything is at a similar focusing distance – such as a landscape at an overlook where everything is near infinity focus – field curvature can cause a significant loss in sharpness in parts of your photo.
The Nikon Z 28mm f/2.8 also has a moderate amount of focus shift. It’s not a massive issue, but be aware that you should always set your aperture first, and then focus, when using this lens. Otherwise, the final focus point may shift backwards slightly as you stop down to narrower apertures.
Related to sharpness is coma, a lens aberration that can make dots of light in the corner of a photo look like smears. Coma isn’t visible in everyday photography, but for something like Milky Way photography, it can be a factor. The f/2.8 maximum aperture of this lens makes it an option for Milky Way photography, at least, so I wanted to put the lens’s coma performance to the test.
The image shown below is an 100% crop from the top-right corner of the Nikon Z7 with the 28mm f/2.8. Specifically, it’s a 915 × 610 pixel crop without any resizing:
Although there’s a bit of coma here, this is good performance overall. I wouldn’t hesitate to use the Z 28mm f/2.8 for Milky Way photography, assuming that the 28mm focal length works for your composition.
A focal length of 28mm and a maximum aperture of f/2.8 isn’t the ideal recipe for lots of background blur. Most of the time, you’ll get too much depth of field for bokeh to be much of a concern in the first place.
Still, if you focus up close on small subjects with the 28mm f/2.8, it’s at least a consideration. Here are a few sample photos showing the Nikon Z 28mm f/2.8’s bokeh performance:
Consider me surprised: The bokeh on this lens is actually really good! Loyal readers of Photography Life know that this isn’t something I say about just every lens – actually the opposite. My recent reviews of the Nikon Z 24-120mm f/4 and Nikon Z 40mm f/2 were both pretty negative in terms of bokeh. But on the 28mm f/2.8, out-of-focus highlights are smooth and not sharply defined. In the corners, too, the bokeh looks pretty good. It’s not as creamy as Nikon’s top 58mm f/1.4G, of course, but that would be asking the impossible. Considering that this is a 28mm lens that maxes out at f/2.8, I have zero complaints here.
The next page of this review dives into the sharpness numbers a bit more, including some head-to-head tests against other lenses on the market. So, click the menu below to go to “Sharpness Comparisons”:
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