4) Lens Sharpness, Contrast and Color Rendition
Let’s take a look at how the lens performed in a lab environment using Imatest:
As you can see, the Nikon 85mm f/1.8G is an excellent lens optically, even at large apertures. It does have a little bit of focus shift and field curvature, which is why some of the corners appear weaker when stopped down. However, I did not find it to be a big problem when using the lens for portraiture in the field.
Bokeh is a very important characteristic of portrait lenses. In this case, we are dealing with three cream machines, especially the 85mm f/1.4G and the 105mm f/2.8G, which are some of the most sought after lenses just because of the way they beautifully render bokeh.
Here is the full image from which I made the below bokeh crops:
Here is a bokeh comparison between Nikon 85mm f/1.8G, Nikon 85mm f/1.4G and Nikon 105mm f/2.8G at maximum aperture:
All three look good and creamy, but the Nikon 85mm f/1.4G stands out with very smooth and less defined bokeh due to its maximum aperture of f/1.4. Let’s see what happens to bokeh when all lenses are stopped down to f/2.8 (still max aperture for the 105mm f/2.8G):
Interestingly, the Nikon 85mm f/1.4G seems to have a slightly smaller diaphragm opening than the 85mm f/1.8G at f/2.8, which results in smaller background highlights. In this case, I actually prefer the bokeh of the 85mm f/1.8G. Overall though, the Nikon 105mm f/2.8G certainly looks the best here due to much less defined and smoother background blur.
While the 85mm f/1.8G has a 7-blade diaphragm (compared to a 9-blade diaphragm on the 85mm f/1.4G), you would not be able to see any difference between the two at large apertures. This is because the new diaphragms on all modern Nikkor lenses are rounded, which only shows defined edges when stopped down to f/4-5.6 and smaller.
If you are crazy about bokeh, this lens certainly has a lot of potential:
Overall, the Nikon 85mm f/1.8G renders great-looking bokeh that is very comparable to the one on the professional Nikon 85mm f/1.4G.
Most prime lenses heavily vignette when shot wide open and the same is true for the Nikon 85mm f/1.8G, so no surprises here. The good news is that as you stop down to f/2.0, vignetting starts to disappear and at f/2.8, it is almost invisible. By f/4 and onwards, it is completely gone. Take a look at lens vignetting at different apertures, as measured by Imatest:
This type of behavior is expected from large aperture lenses, especially when they are mounted on full frame cameras. The Nikon 85mm f/1.4G also vignettes significantly at large apertures, despite its high price tag. The older Nikon 85mm f/1.8D vignettes even more – dark corners are visible even at f/2.8 and f/4.
If you use Lightroom or Photoshop Camera RAW, vignetting is not an issue for this lens, because the Nikon 85mm f/1.8G lens profile is already included in the latest versions of both.
7) Ghosting and Flare
Ghosting and flare are controlled quite well, depending on where the bright source of light is positioned in the frame. It does not do as well as the Nikon 85mm f/1.4G though, because the latter has better lens design and Nano-coating to further reduce ghosting and flare. Here is an image with the sun positioned inside the frame:
The Nikon 85mm f/1.8G has a slight amount of barrel distortion, which is not very noticeable. The older Nikon 85mm f/1.8D had no noticeable distortion in comparison. As I have already pointed out, Adobe already has a built-in lens profile in the Lens Corrections module, so you can easily take care of the problem with a single click.
9) Chromatic Aberration
Lateral chromatic aberration is controlled well, even in high-contrast situations. Take a look at the below results, as measured by Imatest:
Longitudinal chromatic aberration / LoCA (which is the effect of color fringing in front of and behind the focused area), on the other hand, can be quite visible at very large apertures, which is expected for a fast prime lens. Here is an extreme example of LoCA with some axial purple fringing:
Unfortunately, unlike lateral chromatic aberration, LoCA cannot be easily removed in post-processing.
Let’s move on to lens comparisons.