Testing: Longitudinal Chromatic Aberration and focus shift
Although Nikon’s new zoom lens has a focal ratios of only f4.0 I tested for longitudinal color aberrations (loCA, a.k.a. “axial color” or “bokeh CA”) anyway. But there is no coloration and no focus shift to speak of:
Sharpness and contrast
Let’s have a look at the theoretical performance of the new Nikon Z 14-30mm f4.0 S first and compare it to the performance of the Nikon Z 24-70mm f4.0 S and the Tamron 15-30mm f2.8 VC:
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 46MP Nikon Z7 body.
From the charts the new Nikon Z 14-30mm f4.0 S should have an advantage in the fine detail over the Tamron 15-30mm f2.8 VC except for the extreme corner at 30mm. Keep in mind though that the Tamron is shown here wide open at f2.8 while the new Nikon is measured at f4.0. The thing that looks a bit problematic on the new Z-Nikkor is the astigmatism at 14mm which is already pretty strong at the DX-corner and gets even worse towards the FX-corner
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 8/CRAW 11 from RAW to Adobe Color profile with the built-in lens profile applied (Vignette control=N, Diffraction compensation=OFF, Auto distortion control=ON). 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. My first copy of the lens was pretty decentered and produced sub-par results around the lower left DX-corner. I sourced a second copy which was better centered but still shows weaker results in some corners depending on focal length. What follows is the complete series of shots at f4.0 at different focal lengths from my second copy of the lens. I’ve selected the better of the lower left or upper right corner to show the potential of the lens should you source a copy that’s well-centered. 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.
The center of Nikon’s new ultra-wide angle zoom is very sharp across the zoom range. Its DX-corner starts good but gets a little softer towards the long end while the FX-corner suffers from strong astigmatism at 14mm but gets sharper already at 17mm and further towards 30mm.
If you want to see all the details and comparisons with the reference zoom in its class, the Tamron 15-30mm f2.8 VC, 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 14-30mm f4.0 S from f4.0 down to f11 (all crops are from the upper right quadrant) compared to the Nikon AF-S 14-24mm f2.8G ED (shot on a 36MP D810 without application of a lens profile) and the Tamron 15-30mm f2.8 VC (shot on a 46MP D850 without application of a lens profile) at f4.0.
Performance at 14mm:
At the wide end and f4.0 all three lenses look very similar in the center. But the Tamron (at 15mm) beats the new Nikon Z 14-30mm f4.0 S outside the center. Even stopped down the new Z-Nikkor never quite reaches the sharpness of the Tamron. The Nikon 14-24mm f2.8G performs somewhere in the middle between the new Z-Nikkor and the Tamron.
Performance at 17mm:
At 17mm focal length Nikon’s new Z 14-30mm f4.0 S produces an improved FX-corner but still cannot quite match the Tamron outside the center. But the new Z-Nikkor now seems to match or even surpass the venerable Nikon 14-24mm f2.8G.
Performance at 20mm:
At 20mm the new Z-Nikkor bests the Tamron in the center, performs comparably at the DX-corner but is a bit softer than the Tamron in the FX-corner. The Nikon 14-24mm f2.8G looks similar to the new Z-Nikkor. But that may be a bit sugarcoated by the less demanding 36MP sensor of the D810 which was used to test the 14-24mm f2.8G on.
Performance at 24mm:
At 24mm focal length the new Z-Nikkor wins in the center but has the worst DX-corner due to strong astigmatism. But its FX-corner is better than from the 14-24mm f2.8G coming close to the Tamron which (again) outperforms its rivals at the FX-corner.
Performance at 30mm:
At 30mm the new Nikon Z 14-30mm f4.0 S still suffers from a hazy DX-corner but bests the Tamron in the center and FX-corner.
Overall Nikon’s new Z 14-30mm f4.0 S ultra-wide angle zoom performs very similar to the former “gold-standard” in this class, the Nikon 14-24mm f2.8G, which is quite a feat. And it comes close to my current reference-zoom in this class from Tamron but does not depose it: Sometimes the new Z-Nikkor is better but in the FX-corner it mostly trails behind, except at 30mm.
The issue of the soft DX-corner at 24mm and 30mm bothers me a bit as the MTF-chart does not indicate such a behavior. But the second copy of the lens showed this softness in all four corners so it’s not a decentering defect. My advice: have yourself a good look when you buy this lens whether you’re satisfied with the performance of your copy.
Performance at long distances
The Siemens-star test-targets are shot at a distance of 45x focal length (i.e. at around 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. Processing was done in Lightroom 8/CRAW 11 from RAW to Adobe Color profile with the lens-profile for distortion and vignetting automatically applied. Noise-reduction is set to 0, sharpening to 50/0.5/36/10, with no extra tone, color, or saturation adjustment. I used autofocus at the largest aperture and did not change focus for other apertures. All shots were made at ISO 64 and VR switched off.
Following is an overview of the wide-open performance at different focal lengths from my second copy of the lens. You can jump to the detailed results at different apertures and comparisons with the Tamron 15-30mm f2.8 VC (shot on a Nikon D850) by clicking on the crops of the respective focal length. As usual I have selected the diagonal that provided the better corner results.
In this test the new Nikon Z 14-30mm f4.0 S repeats its performance from the short-distance test: It is good to very good in the DX image-circle while the FX-corner is soft at 14mm but gets progressively sharper towards the long end.
If you want to see all the details and comparisons with the Tamron 15-30mm f2.8 VC, read on. Or fast-forward to the next chapter on vignetting.
The main image shows the complete scene wide open to give you an impression of the angle of view. You can access the respective shots up to f11 via the links beneath the main image. Following the main image are 100% crops for each focal length from the new Nikon Z 14-30mm f4.0 S down to f11. For comparison I use the Tamron 15-30mm f2.8 VC (on a Nikon D850 without application of a lens profile) and the Nikon Z 24-70mm f4.0 S (at 24mm and 28mm) both shot on different days.
You can click on each image to access the large original. Please respect our copyright and only use those images for personal use.
Results at 14mm:
The new Z-Nikkor outperforms the Tamron in the DX image-circle but has the clearly softer FX-corner.
Results at 17mm:
At 17mm both lenses look very similar with a slight advantage for the Z-Nikkor in the center and a better FX-corner form the Tamron.
Results at 20mm:
At 20mm the Z-Nikkor is clearly sharper in the DX image-circle than the Tamron which (again) produces the sharper FX-corner.
Results at 24mm:
At 24mm Nikon’s new Z 14-30mm f4.0 S is slightly sharper in the center than the Tamron and as sharp as the Z 24-70mm f4.0 S. In the DX-corner the 24-70mm is best while both the Nikon 14-30mm and the Tamron are a bit soft. Even stopping down does not help the DX-corner of the Nikon 14-30mm much. In the FX-corner Nikon’s new 14-30mm is the sharpest of the three lenses.
Results at 30mm:
At 30mm the center looks very similar from all three lenses, the DX-corner is a bit softer from the 14-30mm, and in the FX-corner the 14-30mm leads closely followed by the 24-70mm and the Tamron.
In this long-distance test the new Nikon Z 14-30mm f4.0 S performed very good: It is a bit better in the DX image-circle from 14mm up to 24mm than the Tamron 15-30mm f2.8 VC which has the lead in the FX-corner up to 20mm. At 24mm and 30mm focal length Nikon’s 14-30mm has the best FX-corners of the three lenses compared here but a softer DX-corner than the Nikon Z 24-70mm f4.0 Z.
The following images show the vignetting of the new lens at 14mm with Vignette control set to normal in camera. The first row was shot without filter, the second row with a 4mm thick 82mm filter:
There is only a small extra darkening in the corners when the filter is applied. Very good! A stack of two filters with a total height of 10mm produces a very visible vignette at 14mm focal length though, regardless of aperture. But this effect is almost completely gone at 16mm focal length.
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 color-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 FF/FX-corner of the new Nikon at various apertures:
On the short end the new Nikon Z 14-30mm f4.0 S practically has no coma to speak of.
Coma at 30mm:
At 30mm focal length the new Nikon Z 14-30mm f4.0 S shows some coma at f4.0, more than the Tamron or the Nikon Z 24-70mm f4.0 S (at 24mm).
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. 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 Bokeh balls of the new Nikon Z 14-30mm f4.0 S at 30mm focal length are small as the lens only sports a focal ratio of f4.0. They show mild onion rings and a distinct outlining in the center. Both effects seem to fade a little towards the corners. What is pretty unique of this lens is that there is no big deformation of the circular shape in the FX-corner, no cat’s eye effect. In comparison the Tamron produces larger Bokeh balls at f2.8 with slightly more distinct onion rings towards the corners.
Now let’s see how this analysis of out-of-focus point-light sources translates into Bokeh-performance shooting a book-shelf.
Naturally Bokeh is not very pronounced with this lens of such short focal length and a focal ratio of only f4.0. Foreground looks a bit smoother than the more important background which suffers from outlining producing double contours. This makes hard contrast edges look nervous. But in comparison to the Tamron at f2.8 the new Z Nikkor does even look a bit smoother in the foreground and background.
The new Z Nikkor goes down to 1:5.4 magnification which is less than the other Z zoom lenses so far. The following images were shot at 1:5.8 magnification where the area of sharp focus is 139 x 209mm. The crops shown below are from 2mm, 12mm, and 20mm off the center of the sensor respectively:
Close-up shooting is not the forte of the Z 14-30mm f4.0 S: to get usable results the len should be stopped down to f8.0. The Z 24-70mm f4.0 S is clearly better in this respect.
Flare, ghosting, and sun-stars
Catching a strong light-source shining directly into the lens is always a risky business: 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 14-30mm f4.0 S for these artifacts I went through a series of well calculated shots against a strong light source to provoke glare and ghosting.
The new Nikon Z 14-30mm f4.0 S is amazingly clear of flare and glare artifacts at the short end and at the long end it’s also very clean. And outside these artifacts the new lens renders a very deep black – even deeper than from the already very good Nikon Z 24-70mm f4.0 S. So there’s very little veiling glare:
The little bright square inset in the upper left of both images 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.
When the light-source is just outside the corner the new Nikon Z 14-30mm f4.0 S does not produce an obvious streak/flare like many other lenses do. Very good! But to get well defined sunstars the lens needs to be stopped down to f8.0.
Next check out my sample images!Check prices on the Nikon Z 14-30mm f4 S at B&H, Adorama, or Wex. Alternatively get yourself a copy of my In Camera book or treat me to a coffee! Thanks!