Nikkor AF-S 50mm f/1.8 G : Review

Introduction

This time I’m bringing to you my review of the Nikkor AF 50mm f/1.8 G lens for the Nikon mount, tested with the Nikon D700 full-frame DSLR. A 50mm lens is always a useful lens on full-frame for many purposes, from candid shots in low light to street photography, closeups and portraits. It is also a popular choice for the novice DX shooter as a first buy, since normal primes are usually cheap, not only for portraiture but also to get something more from their photos than those taken with the kit lenses.
The old 50mm f/1.8 D was a very good lens, and very cheap, but users with entry-level DSLRs could not auto-focus with this lens, meaning that this update was overdue.
After having enjoyed shooting for a couple years with the Nikkor AF-S 35mm f/1.8 G when I had a DX camera, I expected at least the same performance from this new 50mm on FX. This review will show what this lens is capable of in its native format.
For starters, see how the lens looks with a D700:

The lens was introduced in 2011 as a long overdue update for users with entry-level cameras that don’t have an AF drive, giving these users a much cheaper alternative to the f/1.4 G version. It was also about time to finally put an AF-S motor in the lens, since the entire lens lineup had been updated since many years ago. This normal prime lens includes 7 elements in 6 groups, of which one is of aspherical type to take care of optical distortions. It’s an all-plastic lens, including the filter thread, except the mount which is metal, but the plastic has a good quality and is rugged like the other G lenses. Being a G lens means that it doesn’t have an aperture ring anymore.
Having a street price of about 199€, it costs, looks and feels as the 35mm f/1.8 G, which for me it was a very good lens.

Technical Specifications

Focal length 50mm
Maximum aperture f/1.8
Minimum aperture f/16
Field of view 47 degrees (on FX)
Weight 185g
Dimensions 54 x 70mm
Optical construction 7 elements in 6 groups (1 aspherical element)
Aperture blades 7, rounded
Filter diameter 58mm
Minimal focus distance 91cm (37cm from the front element)
Hood HB-47, rounded
Mount Nikon F

Mechanical Characteristics

Zoom ring n/a
Focus ring Plastic with rubber finish, no infinity stop
Focus throw 110 degrees
Focus motor Yes
Optical stabilizer No
Front element rotation while zooming n/a
Front element rotation while focusing No
Internal focusing Yes
Lens extension while focusing No
Lens extension while zooming n/a
Maximum magnification 1:6.5

Handling

The Nikkor 50mm f/1.8 G lens is larger than the previous D version due to the inclusion of an AF motor, although it’s only 30 grams heavier, but looks big on a D3100. It balances and handles nicely on any camera, though, fitting everyone’s hands better than the D version.
The Nikkor is all-plastic made, but the mount is metal. The focus ring is plastic with a rubber finish for more grip but it’s not damped, it’s not smooth and feels like it’s not continuous, but instead feels like there are many tiny bumps while turning it. It doesn’t have an hard infinity stop, therefore one has to focus manually using Live View if we’re taking the lens out for astrophotography. Contrary to other motorized lenses, the focus ring stops turning around a little past infinity, while in those other lenses the focus ring never stops turning around. Thus, the focus ring must not be forced beyond infinity or below minimum focus distance, with the risk of breaking the AF mechanism. Fortunately, I rarely use the focus ring – only in Live View in the dark. The M/A-M switch on the lens means that at the M/A setting the lens allows manual focus override, which can be very useful at times, especially when working with large apertures, to make sure than the lens is focused on the exact spot we want. The throw of about 110 degrees is good for manual focusing.
The front element doesn’t rotate while focusing, so using polarizers is fine.
Speaking about focus speed, the lens focuses fast even in low light and never hesitates. The SWM motor is silent but it’s not amongst the best AF-S motors, there are much faster versions and more silent than this one. It has a problem, though: although the lens seems to focus faster than the f/1.4 G version, the f/1.8 G misses the target like once in every 10 shots when I use apertures greater than f/2.8. And I’m talking about long distance shots. This problem happens even at noon with contrasty subjects. When I use smaller apertures I don’t get any problems. My older trusty 50mm f/1.8 D always focused fast and with precision, but noisier of course. I just played with the f/1.4 G lens for several minutes and don’t know if the misfocusing issue was there too, but the few pictures I took with it were all in focus.
I use the lens mainly on the streets, it’s a snappy shooter and my only complain is the occasional misfocus.

Resolution

For the resolution test I shot the 5 Euro bill as usual. Focus was achieved using Live View to avoid auto-focus imprecisions and to compensate for possible field curvature issues.
The first column shows a crop of the image center, the corner crop is on the second column (the expected DX border) and the third column shows a crop of the extreme FX corner. Each row represents an aperture setting, from maximum to f/16 in full stops. Here are the results:

The center resolution is already great right from the maximum aperture and only drops a little at f/16 due to diffraction. From f/1.8 to f/2, the corner and border resolution is too soft, but there is a tremendous jump in edge-to-edge quality when closing the aperture to f/2.8. By f/4 the resolution is almost on its maximum, which happens at f/5.6, and then it stays on a top level until f/16, where it drops again due to diffraction. Overall, for corner-to-corner sharpness f/2.8 can be used without any problems. This performance is pretty much in line with the Nikkor AF-S 35mm f/1.8 G that I happily owned in the past. Regarding resolution, it’s like one stop better than the previous D version. The sharpness I get with the G lens at f/2.8 is about the same I had at f/4 with the D.

Distortion

Here is the brick wall shot:

There is a small amount of barrel distortion, but less than I got with the 35mm f/1.8 G. Fortunately this small distortion has a simple characteristic and can be easily corrected in post-processing. Of course, I always expect 50mm lenses to have no distortion and this may be worrying for some. In this regard, the 50mm f/1.8 D was perfect.

Vignetting

In this test, I shot a white wall at home using tungsten white balance and set exposure manually:

Vignetting is very strong from f/1.8 to f/2 but is hardly visible by f/2.8. Using the lens wide-open will bring vignetting but the effect might be desireable after all. It can be corrected in post-processing without much effort.

Chromatic aberrations

For this test I shot a car from above on a bright sunny day early in the afternoon:

There is some blue fringing at the edges of the windows until f/2, but only a couple pixels wide. In real shooting I never worry about this, even if I’m shooting metallic objects in bright light. If the reader had played with the 35mm f/1.8 G before, I can tell you that this 50mm is worlds better. This is top performance from any lens. I can’t compare it to the 50mm f/1.8 D because I don’t remember shooting with it wide-open, as it was too soft.

Coma

Coma was tested using a LED source, at home in a dark room.
I put the light source at the center (first column), corner and extreme corner of the frame (second and third columns, respectively), at maximum aperture and stopped down.

The lens has some coma, but it isn’t worrying. I use this lens on astrophotography shots and coma is hardly noticeable. I rate the lens as simply OK regarding coma.

Flare

I shot a building in construction with the sun sneaking from a window, to see if I could see any flare traces. I started to shoot directly against the sun, then placed the sun at the corner and finally made some shots with the sun just outside the frame.

Shot directly against the sun.
Shot with the sun placed at one corner of the frame.
Shot with the sun just outside the frame.

The lens has a good resistance to flare and ghosting, keeping contrast on a high level. The worst case is when the sun is placed at one corner, where multiple reflections of light might be seen towards the other. Shooting against the sun doesn’t produce halos and don’t degrade contrast. When placing the sun just outside the frame is always a good idea to use the supplied lens hood; in this case, the flare visible on the example could easily be avoided with the hood.
In conclusion, this is a good performance which was expected for a normal prime lens.

Bokeh

The lens has 7 blades, which means that it’s almost impossible to render perfect circles. They’re rounded, so it can’t be worse than the awful bokeh that the 50mm f/1.8 D renders.
I took a defocused picture at the widest aperture of the city lights and got crops of the center, corner and extreme corners. The test was repeated for the subsequent two stops.

The lens produces a surprisingly pleasing bokeh, with out of focus highlights that are smooth on the inside and nice edges that hardly can be called distracting. The only downsides are the fact that there are only 7 blades, and the cats-eye distortion on the corners of the frame due to vignetting. This is a quantum leap compared to the bokeh of the 50mm f/1.8 D!

Macro/Close-up

The Nikkor was able to focus as close as 37 centimeters from the front element, resulting in a maximum magnification ratio of only 1:6.5. It’s exactly the same minimum distance as I had when I used the previous D version lens.
I shot an 1 Euro coin and this is what to expect at the minimum focus distance:

Summary

Build quality 5 Almost entirely plastic-made but doesn’t feel too cheap
Handling 6 Fast lens that feels nice in your hand, may misfocus for no reason, manual focusing should be much better
Resolution 9 Amazing resolution, although soft in the corners wide-open
Distortion 7 Unexpected barrel distortion for a 50mm lens, but manageable
Vignetting 8 Strong wide-open, but almost disappears stopped down
Chromatic aberrations 9 Almost invisible in most conditions
Coma 8 Far from perfect, but not problematic in practice
Flare 6 Keeps good contrast, and the hood can help in some situations
Bokeh 7 Always very smooth without accentuated edges, but gets polygonal stopped down
Overall 74% A very sharp prime lens with nice handling and a welcome update for novice users

Samples

Here are some samples of pictures I made with this lens. Settings: native JPEG, picture control set to Landscape mode, no post-processing applied except reducing to 600 pixel width.

50mm, f/1.8, 1/4000s, ISO 200
50mm, f/5.6, 1/640s, ISO 200
50mm, f/4.0, 1/1250s, ISO 200
50mm, f/5.6, 1/200s, ISO 200
50mm, f/2.0, 1/2500s, ISO 200
50mm, f/1.8, 1/4000s, ISO 200
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