Lens Sharpness, Contrast and Color Rendition
As I reveal further down in this review, the performance of the Nikon 40mm f/2.8G DX is excellent throughout the aperture range. You can see many examples of lens sharpness taken in a controlled environment, along with comparisons against other lenses.
Bokeh
Bokeh is a very important characteristic of portrait and macro lenses. While testing the Nikon 40mm f/2.8G lens, I paid close attention to its bokeh characteristics and took a number of shots at maximum and smaller apertures. As you can see from some of sample images in this review and the two sample shots below, the Nikon 40mm f/2.8G DX renders pretty good-looking bokeh in general. Background highlights are very smooth at large and smaller apertures, although some visible outlines could be present around very bright highlights. I would say for a macro lens of this class, there is not much to complain about its bokeh.
Vignetting
Most prime lenses heavily vignette when shot wide open and the same is true for the Nikon 40mm f/2.8G, so no surprises here. The good news is that as you stop down to f/4.0, vignetting decreases significantly and by f/5.6 vignetting is completely gone. Take a look at lens vignetting at different apertures:
If vignetting is an issue for you, it is easy to fix in post-processing, so I would not worry about it. When Adobe adds the lens profile for the Nikon 40mm f/2.8G into their Camera RAW, you will be able to remove the effect of vignetting with a single click through the Lens Corrections sub-module in Lightroom.
When mounting the Nikon 40mm f/2.8G on an FX camera, you get a similar result as with the Nikon 35mm f/1.8G (with DX crop turned off) – the far corners get dark and even darker when stopped down. Here is a sample image of the 40mm f/2.8G mounted on the D3s @ f/11:
Ghosting and Flare
Surprisingly, ghosting and flare are controlled very well on the Nikon 40mm f/2.8G DX Micro. I took pictures with the sun in the frame and right out of the frame and I saw a very moderate amount of ghosting and flares, like on nano-coated pro lenses. This effect might worsen for macro subjects, because the front element comes way out, exposing the front element to bright sources of light. Here is a sample image with a bright reflection of the sun in the center of the frame:
Chromatic Aberration and Distorion
Distortion is also controlled very well, I only saw a small amount of pincushion distortion at close distances. As you move away from the subject, distortion starts to disappear completely. As for chromatic aberration, there is only a very slight amount of it present at large and smaller apertures. However, just like with other Nikkor primes, the amount of longitudinal chromatic aberration (LoCA) is rather high at the maximum aperture of f/2.8, which gradually decreases when the lens is stopped down.
Let’s now move on to the good stuff – Sharpness tests.
Sharpness Test – Nikon 40mm f/2.8G Center Frame
The Nikon 40mm f/2.8G DX Micro has very good center sharpness, as can be seen below. Wide open at f/2.8, the image is a tad softer and slightly darker due to vignetting. Vignetting disappears in the center by f/4.0 and the image gets slightly sharper:
Stopped down to f/5.6 brings even more sharpness and f/8.0 seems to be the sweet spot for this lens:
I am not including smaller apertures, because stopping down the lens beyond f/8 does not improve sharpness and only reduces image quality due to diffraction.
Sharpness Test – Nikon 40mm f/2.8G Corner Frame
The corner performance of the Nikkor 40mm f/2.8G Micro at large apertures is surprisingly good. The lens is already very good at f/2.8 and looks even better at f/4.0:
If it was not for vignetting in the extreme corners, the first image would have looked very close to the second one. Let’s see what happens when we stop down to f/5.6 and f/8.0:
By f/5.6 the lens reaches its maximum sharpness and stopping down the lens further does not improve sharpness. Looks like the sweet spot for the corners is at f/5.6.
Overall, the sharpness results are very impressive for this lens, but the above crops are meaningless without a comparison against other lenses. Let’s move on to comparisons against other lenses available today.
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