Nikkor AF-S 50mm f/1.4G review diary

(Also see our Nikkor AF-S 50mm review in German)

The Nikkor AF-S 50mm f/1.4G was announced in September 2008 as the company’s flagship standard prime lens. It shares the same bright f1.4 aperture and standard focal length as the much older AF 50mm f/1.4D, but features an SWM focusing motor, which means it’ll autofocus quickly and quietly on all Nikon DSLRs, including the D40, D40x, D60, D3000, D3100 and D5000.

It’s compatible with full-frame models like the D700 and D3(x), on which it’ll deliver standard coverage. Mounted on a DX-format body like the D60 or D90, its field is reduced by 1.5 times to deliver an equivalent of 75mm, which is a perfect short-telephoto length for portraits. The fast maximum aperture of f1.4 is also ideal for achieving shallow depth-of-field effects and working in low light. To put this in perspective, an f1.4 lens will gather 16 times more light than one at f5.6, such as the standard Nikkor DX 18-55mm kit lens when zoomed-in.

The optical design is more complex with eight elements in seven groups compared to the seven elements in six groups of its predecessor, and nine rounded diaphragm blades to the older model’s seven for natural-looking out-of-focus effects.

Measuring 74x54mm (maximum diameter by length), the new AF-S 50mm f/1.4G is larger and heavier than its predecessor, and the filter thread is also wider at 58mm. It does now however feature weather-sealing and a non-extending design. The manual aperture ring of the older D model may no longer be present, but there’s still a small window showing focusing distance though, and fans of polarising and other direction-dependant filters will be pleased to hear the end section doesn’t rotate while focusing. The lens also comes supplied with the HB-47 bayonet hood and a flexible pouch.

In this review diary, Cameralabs forum moderator Thomas tests the new Nikkor AF-S 50mm f/1.4G lens on his Nikon D300 body. Thomas is a self-confessed Nikon fanboy and avid nature photographer who uses Nikon Capture NX2 and Adobe Lightroom 2 as his post-processing workhorses, and at the time of writing has almost 4000 images on his flickr account.

Nikkor AF-S 50mm f/1.4G review diary

First impressions

The lens arrived at my doorstep today. It's a little hard to compare it directly against my old Nikkor AF 50mm f/1.4D as I financed the new one by selling the old. But I have still my AF 35mm f/2.0D which has almost identical built-quality and mechanics as the old AF 50mm f/1.4D.

First impressions are that focusing on the new model is much quieter and quicker than the old version – as you’d expect with its SWM focusing motor. But the new 50mm is perhaps not as quick a focuser as you’d hope as the travel of the focus ring itself is so long. This does however make precision manual focusing easier.

The build quality of the new model is "solid plastic" with the movement of the focus ring sharing the same plasticky feeling compared to the focus ring on the older AF-version. But it now has a rubber grommet at the lens-mount which provides environmental sealing.

The design is a little bulkier at 74x54mm and 280g versus 65x43mm and 230g. This actually makes it easier to hold while having the additional benefit of a deeply recessed front-element. What you lose from the new model though is the manual aperture ring. But you do gain a focusing ring that’s broader than the old one and doesn’t turn with AF.

First tests

Nikkor AF-S 50mm f/1.4G with Nikon D300 (cropped-frame DX format) 100% crop from centre		Nikkor AF-S 50mm f/1.4G with Nikon D300 (cropped-frame DX format) 100% crop from corner		Nikkor AF-S 50mm f/1.4G with Nikon D700 (full-frame FX format) 100% crop from corner		To test the sharpness of the lens I photographed the standard Siemens-stars test chart. The best results were with the lens focused using magnified assistance on my D300 in Live View mode. I first focused on the centre of the chart, then took a series of shots one stop apart from f1.4 to f8. I then refocused on the upper right corner of the chart with the camera in the same position and repeated the test. To the left are crops taken from the two sets of images at each aperture setting and presented at 100%. In the third column on the far right you can see corner crops taken from a full-frame FX body, in this case, the D700. You can clearly see the crops suffering from softness at f1.4 and f2.0, but greatly improving at f2.8, and looking quite sharp at f4.0 and above. If you can close the aperture by a couple of stops, you’ll get great performance from the AF-S 50mm f/1.4G, although comparing results against my old AF 50mm f/1.4D, you'll find the new lens is not necessarily sharper than the old one – in fact they’re pretty similar, so don’t buy the new one hoping for an upgrade in image quality alone.
f1.4, 200 ISO		f1.4, 200 ISO		f1.4, 200 ISO
f2, 200 ISO		f2, 200 ISO		f2, 200 ISO
f2.8, 200 ISO		f2.8, 200 ISO		f2.8, 200 ISO
f4, 200 ISO		f4, 200 ISO		f4, 200 ISO
f5.6, 200 ISO		f5.6, 200 ISO		f5.6, 200 ISO

Heading outdoors

After all those indoor tests, it’s finally time to see how it performs at f1.4 in a real-life environment. This first shot was taken with my D300 at 200 ISO at a shutter speed of 1/180 and the aperture wide open at f1.4. The original was cropped to 3595x2542 pixels and reduced in size here for the page, but by clicking on it you can view the cropped original image.

1/180, f1.4, 200 ISO
f1.4

In the meantime, while shooting around today with the AF-S 50mm f/1.4G (a lot at f/1.4) I came across some issues regarding auto-focus. One shot showed a clear focus on the foreground although all focus-indicators lit up on the tree in the background. So I went back to the lab-testing for front / back-focus.

I discovered some back-focus which could be corrected with Micro AF adjustment on my D300, but it varied with distance from the subject. Close-up to the test-chart at 60cm the optimum Micro AF-adjustment was -15, but at 1m it was -5, and finally at 1.8m it was around zero.

This also turned out to be the optimum (non-)adjustment for further-away subjects, such as those at 20m. So next time you use a focus test chart try the results at different distances and if you measure significant variance, go for the one which best matches your typical shooting distance with this lens. Note – the chart crops above were manually focused in Live View, so were not affected by this.

Next up some further remarks on focus. First, the travel of the focus ring is huge: more than 180 degrees, which is considerable for a non-macro lens. Indeed for the motor to run from one extreme to the other takes about three quarters of a second.

As mentioned above, focus is sometimes just off, so check your images for critical sharpness and use Micro AF Adjustment where necessary (if your body offers it). Play in the gearing is also minimal, and much better than my AF 85 f/1.8.

As others have also commented, the bokeh / out-of-focus effect at large apertures is a step-up from the earlier AF 50mm f/1.4D. The second shot, left, was also taken with the lens wide open at f1.4.

A Winter’s morning This early morning I was running around in a cold and foggy dawn with exposures around 1/30 at f/1.4 and 640 ISO. Focusing conditions were far from ideal, but I didn’t observe any hunting from the lens. The photo on the right was captured on this cold and grey December morning. Handheld at 1/45, f/1.4, 200 ISO, with -1EV compensation and the picture mode set to vivid. Post-processing: cropping and some curves. I've converted this to jpg using Capture NX2 and saved it with highest quality setting in full resolution. Click through to a larger image for a closer look. I'm very happy and hope you enjoy this image too! Now this shot below is for everyone on the Cameralabs forums who was asking about focus in low-light: how about under conditions that required quarter-second exposures at f1.4 and 1600 ISO? f1.4, 1600 ISO

1/45mm, f1.4, 200 ISO   To the left is a 100% crop from such an image taken at f1.4, and I'm pleased to report the D300 with the AF-S 50mm f/1.4G didn't hunt for focus - I pointed the central focusing point at the sign's border and it locked-on first time – and remember f/1.4 would be very unforgiving if focus was even slightly off! Note: the 100% crop shown here is taken from a shot using the flash (to eliminate shake) after focussing.

Nikkor AF-S 50mm f/1.4G with Nikon D300 contrast test From left to right: f1.4, f4.0 and f8.0   Nikkor AF 85mm f/1.8D with Nikon D300 contrast test From left to right: f1.8, f4.0 and f8.0

And in contrast...

Here’s my contrast-deterioration-test. A test so cunning, so brutal, that even my venerable Nikkor AF 85mm f/1.8D failed miserably. I set up strong contra-lighting using two halogen-spots shining directly into the lens. Under normal conditions you could expect the lenses to show more contrast when stopped down. So let's see how the new 50mm handles these extreme conditions.

The shots on the right were taken under identical conditions, thus are directly comparable.

They're composites of three images for each lens, from left to right with the aperture wide open at f1.4 or f1.8, then closed to f4 and finally at f8.

As you can easily see, the new AF-S 50mm f/1.4G is much better than the old AF 85mm f/1.8D, although again remember these are extreme test conditions.

But even then, looking at the black under the lens-shade on the 50mm images you can see it becoming progressively more grey-ish when the lens is stopped down. So again we have a case of diminishing contrast, when stopping down. This would be no reason for me to return the lens though. It is far more a testament of how contrasty this lens is even wide open.

Nikkor AF 50mm f/1.4D   Nikkor AF-S 50mm f/1.4G

MTF charts

Now here's the low-down on the lenses innards, directly from Nikon-central, with the old AF 50mm f/1.4D on the left and the new AF-S 50mm f/1.4G on the right.

As you can see, the contrast when wide open (indicated by the red line) on the new lens is better than the old one. And the sharpness when wide open (indicated by the green and violet lines) is higher within the DX format (12.5mm) and more well-behaved than with the older design.

Sagittal flare

Sagittal Coma Flare is an aberration where a point located on the periphery of an image looks like a bird spreading its wings. Sounds odd, but many lenses suffer from it, including the AF-S 50mm f/1.4G. Here’s a series of 100% crops taken from the corner of DX-format images with the lens wide open at f1.4, then closed to f2.8, and finally f5.6.

Nikkor AF-S 50mm f/1.4G with Nikon D300		Nikkor AF-S 50mm f/1.4G with Nikon D300		Nikkor AF-S 50mm f/1.4G with Nikon D300
f1.4, 200 ISO		f2.8, 200 ISO		f5.6, 200 ISO

Yeah, that looks ugly at f/1.4 in the corners of even the smaller DX frame, so we can presume it’s worse still when fitted to an FX-format full-frame body. Point sources of light closer to the centre though look more normal and as you can see above, stopping-down greatly reduces the problem.

Some believe Sagittal Coma could only be avoided if Nikon had used some aspherical glass in the construction of the lens. But that would have catapulted the price of the lens beyond its target point.

Longitudinal Chromatic Aberration (loCA)

One of the critical points with large aperture primes is the phenomenon of longitudinal CA (loCA), where subjects in front of the focus plane are rendered with a reddish outline, while subjects behind the focus plane receive a greenish outline. The effect is not as easily corrected in post-processing as lateral CA and we present the results here with and without correction.

Nikkor AF-S 50mm f/1.4G Longitudinal Chromatic Aberration (loCA)
100% crop, f1.4, loCA removal OFF in Capture NX2		100% crop, f1.4, loCA removal ON in Capture NX2

Above left is the result for the AF-S 50/1.4G showing a 100% crop at f/1.4. As the effect is reduced by stopping down, you can access a large composite images showing the loCA from f1.4 to f/5.6 by clicking on the 100% crop. Processing was done in CaptureNX2 with standard setting meaning lateral CA removal was ON, loCA removal = OFF. At f/5.6 the greenish (background) and reddish (foreground) hues are almost gone - but not completely.

The image above right gives you the results from switching loCA removal to ON at 100%. This works pretty good! Bear in mind that CaptureNX 2's secret sauce for loCA removal seems to depend on the magnification and gets even better the smaller the magnification is (this test-shot was at 1:20). That can be confirmed from real-life shots.

1/4000, f8, 200 ISO

Finally, coming back to one of the strengths of this unassuming little lens.

This shot was taken at f8 shooting directly into the Sun, and as always we’d warn you that doing this is at your own risk.

The important thing to notice in this shot is there’s no obvious flare or ghosting.

I’m pleased with this result and continue to be very satisfied overall with the new Nikkor AF-S 50mm f/1.4G.

I hope this page has been useful and you can continue to find out more about the lens in the Cameralabs forums.