Image quality

The Nikon Z 50mm F1.8 S offers outstanding resolution even wide open, but is practically immaculate at normal working apertures, delivering excellent resolution across the frame, with virtually no aberrations.

Converted Raw| ISO 100 | 1/500 sec | F5.6 | Nikkor Z 50mm F1.8 S

While there are some benefits to wide apertures unrelated to image quality (more light for autofocus sensors being perhaps the main one), most photographers would agree that an F1.4 or larger maximum aperture is only useful if the images taken at those settings look good. And typically, fast primes look great in the center when shot wide open, OK in the middle, and a bit ropey at the edges. There are exceptions, but those exceptions tend to be large, heavy and usually very costly.

Considering typical use-cases for such lenses, the compromises presented by an average 50mm F1.4 or F1.8 aren't really a problem. After all, you're not going to shoot landscapes wide open on a fast 50mm, are you?

Sharpness, flare and coma

Except - wouldn't it be nice if you could?

With the Nikon Z 50mm f1.8 - like Sony's FE 55mm F1.8 ZA, another 'new generation' 50mm - you can pretty well get away with it - at least at 24MP. On the more demanding sensor of the Z7 some softness is visible at the edges and corners but even so, there's not much to complain about unless you're really pixel peeping. Across most of the frame there's minimal coma, even at at F1.8. Lateral CA (which is easy to remove in post) is similarly negligible, probably aided by automatic profiling.

Compared to the Sigma 50mm F1.4 Art - an excellent lens1 - the Nikon clearly offers superior resolution and much less coma at wide apertures, before things even out at f2.8 and beyond. By F5.6 both lenses offer practically the same resolution, but the Sigma delivers noticeably more attractive description of point highlights.

Shot at F1.8 on the Nikon Z7 (again, on a tripod with Vibration Reduction turned off), this image further demonstrates the Z 50mm F1.8 S's excellent sharpness, even wide open.

Converted Raw| ISO 400 | 1/25 sec | F1.8 | Nikkor Z 50mm F1.8 S

The end result is that while there are plenty of great 50mm lenses out there, the Nikon Z 50mm F1.8 S is an unusually useful one for low-light, general-purpose handheld photography, where every photon counts. The Sigma 50mm F1.4 Art is a great lens, but it can't compete in terms of resolution at wide apertures. Please note that images from both lenses shown in the above widget (and indeed all of the images in this review) were converted from Raw at our standard ACR settings for lens samples (sharpness dialed back to +25, radius 1, no luminance noise reduction or attempt to correct for vignetting or CA). There's not much you can do to make coma look nice, but files from both lenses can be made to look sharper and cleaner with a little work in a Raw converter.

By F8, as we'd expect, the Z 50mm F1.8 is sharp everywhere. This shot (taken on a Z6) is included to demonstrate the lens' flare-resistance. With the sun just out of frame at upper-left, there's barely a hint of flare and contrast is high.

Converted Raw| ISO 100 | 1/400 sec | F8 | Nikkor Z 50mm F1.8 S

Long story short - unless you need the additional depth of field of smaller apertures, you can shoot this lens wide open without worrying too much about the usual nasties. This is a major advantage of the Z 50mm compared to any of its F-mount predecessors, and even competitors like Sigma's 50mm F1.4 Art.

A nighttime scene, shot wide open, containing an incredibly bright, off-center light source - a classic recipe for flare and ghosting.

Converted Raw| ISO 640 | 1/30 sec | F1.8 | Nikkor Z 50mm F1.8 S
Sure enough, if you look at the lower portion of this image, just to the left of center, you'll see that the Z 50mm f1.8 S isn't entirely immune.

When it comes to flare, the Z 50mm F1.8 S also delivers excellent performance. Even deliberately trying to induce flare by shooting without a hood with the sun just out of frame, I can only see it in a handful of daytime shots. The image above, shot after dark, is a real stress test, and shows both flare and a clear 'ghost' image of one of the spotlights - always a risk with mirrorless systems where lens rear elements are so close to the sensor, but of minimal concern here, even so.

Bokeh and LoCA

Of course, image quality isn't just about sharpness and coma. For some kinds of photography - particularly portraiture - other factors come in, like bokeh and LoCA. And they're fun to say in a sentence, because they sort of rhyme.

Bokeh refers to the aesthetic quality of out of focus areas in photographs, and it is the subject of about 50% of the arguments on our forums (the other 50% is an even split between equivalence and how many card slots cameras should have).

If you look closely at the specular highlights in the middle background of this photograph you'll see slight 'bullseyes'. This is about as bad as the issue gets on the Z 50mm F1.8 S.
Photo by Dan Bracaglia

Converted Raw| ISO 100 | 1/320 sec | F4 | Nikkor Z 50mm F1.8 S

Our old friend Jimi, playing the world's longest-ever sustained note on Broadway, Seattle. Shot from a moderate distance at F1.8 you'll see that the bokeh balls in the background of this image aren't the smoothest, nor the roughest, and LoCA is hardly noticeable except around the bright white points at upper left.

Converted Raw| ISO 450 | 1/30 sec | F1.8 | Nikkor Z 50mm F1.8 S

You can use the widget below to get a general idea of how the Z 50mm F1.8 stacks up in terms of bokeh compared to several of its 50mm and 55mm peers. Bear in mind that this is a 'stress test', shot deliberately to reveal ugly bokeh and longitudinal CA (LoCA) and by default, we're scaling to ~8MP, to make side-by-side comparison of specific bokeh balls easier. You can take a closer look at 100% by hitting the 'Full' button at upper right.

In terms of bokeh, the Z 50mm f1.8 is neither the best-looking lens out there (Sigma's 50mm F1.4 Art is very pretty indeed) nor the worst. It's very sharp where it's meant to be and gives pleasingly soft out of focus areas at wide apertures, albeit with some 'onion ringing' patterns visible in defocused high brightness point light sources. Transitions from sharp to soft are pleasantly smooth in most instances, with only slight 'nervousness' visible occasionally. Importantly for portraits, strands of hair in this 'transition zone' are rendered very nicely. By F2.8 most of the lenses we shot for this example give similar rendering. The Nikon Z 50mm F1.8 actually has extremely similar 'bokeh ball' characteristics to Sony's FE 55mm F1.8 ZA, except for one thing: longitudinal chromatic aberration, or LoCA.

LoCA is an abbreviation of 'longitudinal chromatic aberration', which is the purple and green fringing you often see in photographs made using wide aperture lenses, in out of focus areas in front of and behind the plane of focus. This is not to be confused with lateral chromatic aberration (CA) which takes the form of colored fringes around high-contrast scene elements at the edges of an image. You can see LoCA on the Sony lens as green rings highlighting bokeh balls, and as green outlines around some strands of hair in the focus transition zone - which would be far more obvious were the background white. For a closer look at the FE 55mm F1.8 ZA, we published a detailed analysis of that lens back in 2016, which you can find here.

If you look very closely at this shot, taken at F1.8, you'll see a hint of a green tinge in the backlit tree branches in the upper left. This is about as severe as LoCA from the Z 50mm F1.8 S gets, in normal use.

Converted Raw| ISO 720 | 1/60 sec | F1.8 | Nikkor Z 50mm F1.8 S

Whereas bokeh is somewhat subjective, LoCA, where it appears in images, is simply unattractive. And unlike lateral CA it is also near-impossible to correct, either automatically using a profile, or post-capture. In short, it's bad news, and it has plagued Nikon's F-mount primes for a long time. You can clearly see that the Sony 55mm and F-mount Nikon 50mm have moderate LoCA, whereas the Nikon 50mm Z has virtually none. This is also true in more realistic, day to day shooting situations - the Nikon Z 50mm F1.8 S is extremely well-corrected for LoCA, which is good to see (or rather, good to not see). 2

You might occasionally detect a slight green tinge in some out of focus highlights in backgrounds (tree branches on a white cloudy sky or shiny reflections on a wire fence receding into the background being the classic stress tests) but compared to some of its competitors (and in fact the Z 35mm F1.8 S) it's barely a factor.

Another shot showing sharpness at F1.8, but take a look at the 'transition zone' as my subject's hair starts going out of focus, just behind the plane of sharpness. It's pleasantly smooth and (again) unmarred by LoCA. With a lower-contrast, organic background (as opposed to our stress test, above) the bokeh in this image is very nice, too.

Converted Raw| ISO 64 | 1/80 sec | F1.8 | Nikkor Z 50mm F1.8 S

This is a very welcome development, since traditionally, LoCA is the bane of Nikon prime shooters' lives. There's an argument to be made that LoCA should be considered part of bokeh (I did say they rhymed) since it's a major factor in how nice (or not) out of focus highlight areas look. Viewed alongside to the green-ringed bokeh balls created by Nikon's older AF-S 50mm F1.4 and the Sony FE 55mm F1.8 ZA, the Z 50mm F1.8 S's rendering is definitely more attractive, albeit not a match for Sigma's lovely 50mm F1.4 Art.

With in-camera corrections turned off, vignetting is obvious at F1.8 (it's roughly 2 stops at the extremes), much reduced even at F2, and all but unnoticeable beyond F2.8. At no point do corners become too dark to obscure detail. Switching in-camera vignetting correction to 'normal' reduces the effect even further. Distortion is effectively nil, thanks at least in part to automatic correction.3

1). We're comparing against the Sigma 50mm F1.4 Art here, since it is commonly regarded as a benchmark third-party lens, and with the Nikon FTZ adapter, it is fully-compatible with the Z6/7. It gives a slightly wider field of view to the Nikon Z 50mm F1.8 S, so when you're looking at the extreme edges in our widget, you're looking at the absolute extent of the Nikon's field of view. The Sigma actually captures a little more on all sides.

2). It's worth noting here that we've shot controlled tests with two samples of the Z 50mm F1.8 S and they have very slightly different bokeh renditions, but neither is 'better' or 'worse' than the other. This sort of variation isn't unusual in lenses that use molded aspherical elements (since manufacturing involves multiple molds and no two molds are exactly identical).

3). If you're reading this thinking "but you said that the Z 50mm F1.8 S was one of the least favorite lenses of 2018!", you're right - and we were wrong. It shouldn't have made that list. A series of mixups and miscommunications among the team lead to some of our conclusions from an early preproduction sample of the Z 35mm F1.8 S being muddled up with our preliminary findings from the Z 50mm F1.8.