4) Lens Sharpness and Contrast
The quality of the images produced by the Nikon 19mm f/4E PC is fantastic. Sharpness is even across the frame, including when making large shifts. At f/4 sharpness is very good, but this lens really shines at f/5.6, showing exceptional performance. Colors and micro-contrast are what you would expect from a professional lens. I would characterize the images as cool in tone. More information on the lens sharpness, along with comparisons to other similar focal length lenses can be found further down in this review.
Nikon’s 9-blade rounded diaphragms deliver very smooth bokeh. The Nikon 19mm f/4E PC is no different; it delivers consistently smooth, round bokeh balls. I was somewhat surprised at how well this lens renders out of focus elements. Many wide-angle lenses do not render out of focus elements smoothly or consistently across the frame. Even when tilting and shifting, I did not see the bokeh balls become malformed. But this is not something you would generally have to worry about – after-all, wide-angle lenses and especially tilt-shift lenses like the 19mm f/4E PC are not made for bokeh – even wide open at f/4 and a relatively close subject at minimum focus distance, you will have a hard time getting things out of focus in the background. Here is an image where I exaggerated bokeh by intentionally de-focusing the subject:
At the same time, bokeh can definitely become important when tilting a scene, as can be seen from some of the sample images in this review.
Most lenses experience light falloff, also known as vignetting, in the corners when shooting at maximum aperture. The Nikon 19mm f/4E PC is designed to yield practically no vignetting. Even at its maximum aperture of f/4, the amount of vignetting is only stronger at infinity focus and it never passes above 0.8 EV, which is very impressive. Once stopped down to f/5.6 and smaller, vignetting is almost non-existent – you will not notice it in images. Below is how Imatest measured vignetting for the lens at different apertures:
Unlike traditional lenses, tilt-shift lenses project an image circle much larger than the camera sensor so that barrel movements do not cause extreme vignetting. However, falloff does become apparent as the Nikon 19mm f/4E PC nears maximum shift. Stopping down to f/5.6 definitely helps a great deal though, as indicated above. Combining heavy tilt and shift can result in light not reaching the edge of the sensor at all, but this is a rare use case.
7) Ghosting and Flare
When a bright light source enters a lens directly it can cause unsightly spots resulting from light reflecting off of glass elements inside the lens. Ghosting and flare are especially common with wide-angle lenses with their large fields of view and small lens hoods. Many Nikon lenses use a coating technology called Nano Crystal Coat to reduce reflections inside the lens. The Nikon 19mm f/4E PC is equipped with this technology. In my testing, the 19mm f/4E PC handled bright light sources very well considering that it has a wide angle of view and no hood:
Keep in mind that the amount of ghosting and flare you will see in images will vary depending on where the light source is in the frame, its size and how strong the light source is is. If you are planning to include the sun in the frame and you see strong ghosting and flare, consider moving the sun in the frame or use Nasim’s technique to eliminate ghosting and flare in images.
8) Chromatic Aberrations
Chromatic aberration (CA) is an unsightly green, purple or magenta outline found near areas of high contrast in an image; for example, black lines against a bright sky can cause CA. This optical design defect is most prevalent at the edges of the frame in wide-angle images. The Nikon 19mm f/4E PC is designed in such a way that its lateral chromatic aberrations are minimized at all apertures. Even in the most contrasty situations, I saw only minimal CA in resulting images. Shifting the lens to its outer limits may increase CA a bit, but in my testing this was extremely minimal. Here is an image captured with a very bright sky:
And here is a 100% crop from the image that shows a very slight amount of lateral chromatic aberration:
Below is data extracted from Imatest:
As you can see, at wide open aperture of f/4, there is about 1.25 pixel of vignetting, which gets reduced as the lens is stopped down.
When it comes to distortion, as expected from a wide-angle lens, the Nikon 19mm f/4 PC definitely shows signs of distortion, especially at close distances. Imatest measured 0.95% barrel distortion, which is in line with the Nikkor 24mm f/3.5 PC-E, which has a little less 0.82% barrel distortion. The only wide-angle lens that stands out in this category is the Sigma 24mm f/1.4 Art, which shows practically no barrel distortion at close focus.
Unless you are planning to shoot straight lines at relatively close distances, you should not worry about fixing distortion in post. The lines in the above image look straight and the image was not corrected for distortion in post, just like all the other ones in this review.
10) Sharpness Test
Before we dive into sharpness figures and start comparing lenses, I would like to point out something very important: designing wide-angle tilt-shift lenses is a pretty tough challenge, especially when it comes to resolving power throughout the frame. The Nikon 24mm f/3.5 PC-E was a very good lens until 36 MP sensors arrived. That’s when we started seeing that the lens was not all that good, especially towards the edges of the frame. It took Nikon many years to introduce the 19mm f/4E PC, which was specifically designed for high-resolution sensors. Let’s take a look at how the lens performed in our lab tests using Imatest:
Right off the bat, the Nikon 19mm f/4E PC shows pretty impressive wide open performance in the center of the frame. Considering how close the lens was to the test target, even mid-frame and the edges look really good at f/4, which is something many lenses struggle with. Sharpness peaks at f/5.6 and once stopped down further, the performance of the lens starts to diminish rather quickly.
How good are the above numbers and what do they mean? Let’s find out by comparing the lens performance to popular wide-angle lenses from Nikon.