Testing: Longitudinal Chromatic Aberration and focus shift
Lenses with focal ratios of f2.8 or larger are often prone to longitudinal color aberrations (loCA, a.k.a. “axial color” or “bokeh CA”). These normally show up as magenta coloration in the foreground and greenish hues in the background and are not easily corrected in post-processing. The new Z-Nikkor has almost no loCA. Very good!
There’s also no focus shift to speak of although at 24mm the foreground becomes sharper faster than the background. I also detected no purple fringing around high-contrast edges in the focal plane:
Sharpness and contrast
Let’s have a look at the theoretical performance of the new Nikon Z 14-24mm f2.8 S first and compare it to the performance of the Nikon AF-S 14-24mm f2.8G and Nikon Z 14-30mm f4.0 S:
These MTF charts show the computed lens-performance of lenses wide open without influence of diffraction. Higher values are better (more contrast) and the closer the line-pairs are together the less astigmatism (= resolution depends on the orientation of the test-pattern) the lens has. The x-axis displays the distance from the optical axis (=center of the sensor) in mm. I’ll show you the real-life performance at 4 mm (center), 13 mm (APS-C/DX-corner), and 20 mm (FF/FX-corner) on a 45MP Nikon Z7 camera.
The new optical construction has lifted resolution and contrast of the new zoom lens considerably compared to the F-Nikkor. Especially on the wide end astigmatism (and hopefully field-curvature) and corner resolution is greatly improved. But the comparison also shows how good the Z 14-30mm f4.0 S is – albeit at a one stop slower aperture. [+]
Let’s see how this theoretical performance translates into real life results in the sharpness test based on Siemens-stars. Processing was done in Lightroom 10.0/CRAW 13.0 from RAW to Adobe Color profile with the built-in lens profile for vignette, distortion, and CA compensation applied. Noise-reduction is set to 0, sharpening to 50/0.5/36/10, with no extra tone, color, or saturation adjustment. White-balance was adjusted to a neutral white and I did some exposure compensation to make the brightness of all crops match. So you will not see light fall-off in the corners.
The following are all 100% crops!
First up is an overview of the wide-open performance at different focal lengths. You can jump to the detailed results at different apertures and comparisons with the competition by clicking on the crops of the respective focal length.
Nikon’s new zoom lens looks very sharp in the DX image circle throughout the zoom-range with only a slight softening towards the FX-corner – which gets gradually softer towards the long end. The lens also exhibits only very little field curvature over its zoom range. Very good!
If you want to see all the details and comparisons, read on. Or you can fast-forward to the performance at long distances.
The following 100% crops for each focal length show the new Nikon Z 14-24mm f2.8 S from f2.8 down to f11 compared to the Nikon 14-24mm f2.8G and the Nikon Z 14-30mm f4.0 S at f2.8 resp. f4.0.
Performance at 14mm:
At 14mm focal length the new Z 14-24mm f2.8 S is a tiny bit sharper than the F-Nikkor in the center but that advantages becomes ever clearer towards the corners. The Z 14-30mm f4.0 in comparison (at f4.0) is even a bit sharper in the center than the new zoom lens, a little bit behind at the DX-corner, and clearly softer in the FX-corner.
Performance at 17mm:
Same story as at 14mm focal length.
Performance at 20mm:
At 20mm focal length the Z 14-24mm f2.8 S profits visibly from stopping down to f4.0 and now pulls slightly ahead of the Z 14-30mm f4.0 S in the center making it the best lens across the sensor in this comparison.
Performance at 24mm:
At 24mm focal length the Z 14-24mm f2.8 S is again better than the F-Nikkor across the sensor at f2.8. Its FX-corner profits clearly from stopping down to f4.0 but stays softer than the FX-corner of the Z 14-30mm f4.0 S.
Overall Nikon’s new Z 14-24mm f2.8 S zoom lens performs better than its very good F-mount sibling. And the Z 14-30mm f4.0 S shows again that it came Highly Recommended for good reason.
Performance at long distances
The Siemens-star test-targets are shot at a distance of 45x focal length (i.e. at around 1.1m for 24mm focal length). But performance of lenses also depends on the shooting distance. Therefore I present another series of test-shots of a city around 1 km away on a 45MP Nikon Z7. Processing was done in Lightroom 10.0/CRAW 13.0 from RAW to Adobe Color profile with the built-in lens profile compensating CA, distortions, and vignetting. Noise-reduction is set to 0, sharpening to 50/0.5/36/10, with no extra tone, color, or saturation adjustment. I used manual focus at the largest aperture and did not change focus for other apertures. All shots were made at ISO 64 and image stabilization switched off.
Following is an overview of the wide-open performance at different focal lengths. You can jump to the detailed results at different apertures and comparisons with other lenses by clicking on the crops of the respective focal length. As usual I have selected the diagonal that provided the better corner results as almost any lens is a bit decentered.
In this long-distance test the new zoom lens looks (again) very good across the sensor at every focal length with a slight softening of the FX-corner towards the long end.
If you want to see all the details and comparisons, read on. Or fast-forward to the next chapter on vignetting and distortions.
The main image shows the complete scene wide open to give you an impression of the angle of view and to judge vignetting. Following the main image are 100% crops from the center, DX-corner, and FX-corner for each focal length from the new Nikon Z 14-24mm f2.8 S down to f11. For comparison I use the Nikon AF-S 14-24mm f2.8G shot on an FTZ adapter only minutes apart. Plus the Nikon Z 14-30mm f4.0 S shot on a different day with less humidity in the air which results in a higher overall contrast in comparison to the other two lenses. But you can still compare resolution of fine details quite well.
You can access the large originals but please respect our copyright and only use those images for personal use.
Results at 14mm:
At 14mm the F-Nikkor is clearly softer than the new Z zoom outside the center. There’s also a clear lead of the new Zoom in the FX-corner over the Z 14-30mm f4.0 S.
Results at 17mm:
Same story as at 14mm, although the FX-corner of the Z 14-30mm f4.0 S now closes the gap a bit.
Results at 20mm:
Stopping down to f4.0 helps lift performance of the Z 14-24mm f2.8 S a bit.
Results at 24mm:
At 24mm the F-Nikkor is now considerably softer outside the center while the Z 14-30mm f4.0 S again surprises with a very sharp FX-corner.
Again the Nikon Z 14-24mm f2.8 S shows better performance than the Nikon AF-S 14-24mm f2.8G with the Z 14-30mm f4.0 S hard on its heels.
Vignetting and distortions
To make it easier to see light fall-off in the corners of a full-frame sensor I’ve arranged a series of three shots each with the new Z-Nikkor at f2.8, f4.0, and f5.6. All images were developed to the same brightness in the center and are shown with vignette control Off (1st row) resp. Normal (2nd row):
At 14mm unmitigated vignetting is relatively strong at f2.8. But the lens profile takes good care of this although it is not completely eliminated. With vignette control set to normal the extreme corners are lifted about 0.75 EV at f2.8. Adobe’s RAW converter automatically applies vignette control as it was set in camera – but you cannot alter the setting in postprocessing.
The same applies to distortion control: Adobe’s RAW converter automatically applies what was set in camera – but you cannot alter it in postprocessing. Barrel distortions at 14mm focal length are pretty strong and turn to a slight pin-cushion at 24mm (see below).
Rendering of point-light sources at night-shots
Night-shots pose a different challenge for lenses as the contrast is even higher than under bright sun and point-light sources can reveal some weaknesses such as coma, haloing and colour-aberrations that do not show up as prominently in other test-shots. The 100% crops below the main image show the effect of coma in the FX-corner of the new Z-Nikkor compared to the F-Nikkor at various apertures:
On the short end coma is pretty well controlled with all three lenses. Let’s have a look at the long end:
On the long end the Z 14-24mm f2.8 S shows a bit of coma but less than the AF-S 14-24mm f2.8G or the Z 14-30mm f4.0 S.
Rendering of out-of-focus point-light sources
This test is for the rendering of point-light sources in an out-of-focus background. The circle of confusion that is produced by this test is pretty indicative of Bokeh performance (in the background) and light fall-off. Ideally the out-of-focus image of the point-light is evenly lit and perfectly circular, with no “onion-rings”, and without coloration. Large aperture lenses normally produce an effect known as “cat’s eye” the further away from the optical axis the point-light is projected. This is due to optical vignetting in the lens barrel when light enters the lens from an angle.
The new Z-Nikkor is first, followed by the F-Nikkor. Crops are from near the center, DX-corner, and FX-corner resized to make them comparable across all my reviews.
All three lenses suffer from outlining which could lead to a nervous Bokeh. Onion rings are relatively mild and the cat’s eye effect towards the corners is pretty moderate. Green coloration from loCA is also absent. The difference in size of the Bokeh balls between the new Z-Nikkor and the F-Nikkor in the center crops may be down to a slightly different focus distance set for both lenses. Normally there should be none as both lenses have the same entrance pupil at 24mm, f2.8.
Now let’s see how this analysis of out-of-focus point-light sources translates into Bokeh-performance shooting a book-shelf. Crops are from the foreground, middle-ground, and background resized to make them comparable across all my reviews.
Both f2.8 lenses have a softer Bokeh than the Z 14-30mm f4.0 S with the AF-S 14-24mm f2.8G rendering the slightly softer transition in the middle-ground. Looking at another crop (now at 100%) from the same image showing the ruler reveals that the new Z 14-24mm f2.8 S can produce some nasty double contours / outlining on fine structures near the plane of sharpest focus. But the further away the background is the more rare this effect becomes.
Flare, ghosting, and sunstars
Catching a strong light-source shining directly into the lens is always a risky business – especially with ultra-wide lenses: it could produce strange colorful ghost-images or reduce contrast considerably through flare and glare. The appearance of flare and ghosting depends on factors like the aperture and the angle of the light hitting the lens. So to judge the proclivity of the new Nikon Z 14-24mm f2.8 S for these artifacts I went through a series of well calculated shots against a strong light source to provoke glare and ghosting. The lens hood was mounted in all shots. Following are two typical example results. The little bright square inset in the upper left shows the respective area with an exposure compensation of +3 EV to make it easier to see which levels of black the lens renders at that point:
The Nikon Z 14-24mm f2.8 S is very clear of flare and ghosting artefacts and the lens renders a very deep black, so there’s little veiling glare. An excellent result especially for a complex zoom lens – and much better than from the AF-S 14-24mm f2.8G. There’s only a muted flare from the upper right corner which only occurs at a very narrow angle when the light-source is just outside the corner. Stop down to f11 to get well defined sunstars at 14mm. At 24mm focal length (and f11) the sunstars are a bit less spikey.
All-in-all the Nikon Z 14-24mm f2.8 S let’s you shoot confidently under adverse contra-light situations. The only drawback being that the Z7 might add some colorful “teardrops” to very bright sunstars as can be seen above. This effect does not always show up though.
Next check out my sample images!Check prices on the Nikon Z 14-24mm f2.8 S at B&H, Adorama or WEX! Alternatively get yourself a copy of my In Camera book or treat me to a coffee! Thanks!