Studio Tests

The Nikon 35mm F1.8G DX performs much as we'd expect from a fast prime in our studio tests. The lens is a somewhat soft wide open but improves rapidly on stopping down, however there's an associated increase in lateral chromatic aberration (this is the most marked difference to a traditional full-frame standard prime such as the AF-Nikkor 50mm F1.8D, and presumably a result of the retrofocal design). However when compared to the AF-S Nikkor 18-55mm F3.5-5.6G DX VR kit lens, the significantly higher sharpness of the prime is immediately apparent.

Sharpness	Sharpness is high in the centre even wide open, but deteriorates progressively towards the corners; examination of the checkerboard crops shows that this is essentially loss of contrast due to slight halation, and detail is rendered with high definition. This improves rapidly on stopping down, and by F2.8 is very good right across the frame (although the extreme corners are always slightly less sharp than the centre). The very best results are seen around F3.5, but near-equally excellent results are obtained on stopping down to at least F8, with diffraction having a progressively more destructive impact at smaller apertures. As usual on DX sensors, F18-F22 is best avoided.
Chromatic Aberration	At large apertures chromatic aberration is very low, however on stopping down lateral CA progressively increases up to F4. At this and smaller apertures red/cyan fringing is rather marked, certainly high enough to be visible in many shots.
Falloff	We consider falloff to become perceptible when the corner illumination falls to more than 1 stop less than the centre. The 35mm F1.8G has a maximum falloff value of 1.3 stops wide open; this is lower than that seen on traditional FX-format 50mm primes, and nothing to worry about in normal use.
Distortion	Distortion is reasonably well-controlled at 1.1% barrel - about par for the course for standard primes, although rather higher than the exceptionally well-corrected Nikon 50mm F1.8D. It is high enough to occasionally become visible in real-world shots, but in context much lower than that seen at the wide end of most kit zooms.

Macro Focus

Standard primes are not really intended as macro lenses, and the 35mm F1.8G follows this trend. Maximum magnification is 0.18x, at a measured closest focus distance of 27cm, which gives a working distance of 17cm from the front of the lens to the subject. Optical quality is quite acceptable, if not wonderful; central sharpness is high, but the corners of our test chart never fully sharpen up on stopping down, indicative of curvature of field. There's also obvious barrel distortion, and quite high levels of lateral chromatic aberration.

Macro - 129 x 85 mm coverage Distortion: moderate barrel Corner softness: low Focal length: 35mm

FX (Full Frame) Coverage

On the release of this lens (in amongst some dismay over it being DX format only) there was a degree of speculation as to how fully it might cover the FX / 35mm full frame format. The lens will mount on Nikon FX bodies, which by default will engage DX crop mode and therefore shoot at reduced resolution. But it's also possible to force the camera to shoot in FX mode, so in the samples below we show the degree of vignetting which will occur if you do so (with the DX format frame superimposed in red for reference).

The vignetting observed is dependent upon two factors - distance and aperture - with the affected area decreasing on focusing closer, and the affect becoming progressively more hard-edged on stopping down. But while the image circle appears slightly more generous than the most of the other DX lenses we've tested, only at the minimum focus distance does corner darkening disappear fully. At normal shooting distances there's always a degree of vignetting visible, and of course this test reveals nothing whatsoever about softness or aberrations outside of the DX image area for which the lens was designed.

The more adventurous shooter may still wish to play with this lens on FX, and could perhaps extract useful images somewhat wider than the DX crop area. However, just as we'd expect, the AF-Nikkor 35mm F2 D remains a far more sensible option for users of both formats.

Infinity, F1.8	Infinity, F8	Infinity, F22
1m, F1.8	1m, F8	1m, F22
0.3m, F1.8	0.3m, F8	0.3m, F22

Specific image quality issues

As always, our studio tests are backed up by taking hundreds of photographs with the lens across a range of subjects, and examining them in detail. This allows us to confirm our studio observations, and identify any other issues which don't show up in the tests. The Nikon 35mm F1.8G DX turns out to be a highly capable and reliable lens, producing good results in all conditions.

Flare

The 35mm F1.8G DX is relatively resistant to flare for a large-aperture prime, and does very much better than the various designed-for-film 50mm F1.4 lenses we've tested recently. With the sun in the corner of the frame we see relatively little in the way of flare, with just a multi-colored pattern in the opposite corner which (as usual) increases in definition and intensity on stopping down. Move the sun just outside the frame area and, although there's an overall loss of contrast, there's nothing resembling the sheets of veiling flare seen with older large-aperture designs. Overall, a pretty decent result.

F8, Nikon D300	F1.8, Nikon D300

Chromatic aberration

A large maximum aperture retrofocal design is always likely to suffer from a degree of chromatic aberration, and there's simply no getting away from the fact that color fringing of various flavors is often visible in shots from this lens. And while the sophisticated JPEG processing routines in Nikon's latest DX DSLRs (the D300 and D90) are very effective at suppressing lateral chromatic aberration, owners of older cameras, or the entry level cameras such as the D60, won't see these benefits. Equally longitudinal chromatic aberration (i.e. color fringing based on subject distance) is not readily correctable in software, and will be visible to all users.

First let's look at lateral chromatic aberration. This lens exhibits red/cyan fringing, which can be readily visible on high-contrast edges towards the edge of the frame. This is the type which Nikon's JPEG processing can remove, and the the examples below show both the magnitude of the issue and the effectiveness of the correction. In the process, fine detail is also rendered in a more convincing fashion.

Nikon D300, RAW + ACR	Nikon D300, JPEG
F4, ISO 200
100% crop, lower left

The lens also shows some longitudinal chromatic aberration, in other words fringing around high contrast edges dependent upon subject distance, mainly visible at large apertures. This is common with fast primes, and the 35mm F1.8 DX is really little better or worse than we'd expect. Stopping down progressively diminishes the effect, until it more or less disappears by F4.

The color fringing is magenta in front of the plane of focus, and green behind it; however the region of sharpest focus still shows a degree of magenta fringing, and the neutral region with no fringing is slightly behind that. As the examples below show, this is uncorrectable by the camera's processing, as it can occur anywhere within the frame and is purely dependent upon image content.

Nikon D300, RAW + ACR	Nikon D300, JPEG
F1.8, ISO 200
100% crop, plane of sharpest focus
100% crop, in front of focus plane
100% crop, behind plane of focus

The fringing around in-focus areas seen above implies that 'purple fringing' around specular highlights at large apertures could be quite prevalent with this lens, and this turns out to be the case. Green fringing around out-of-focus background regions is also often visible, and can be accompanied by a magenta 'fill'. If you wish to avoid this, stopping down to the region of F2.8 or smaller is advisable. Note also that the examples shown below are shot under somewhat atypical conditions (with the aperture wide open in contrasty, bright sunlight); for more typical uses of large apertures (low-light shooting, especially indoors) you'll rarely see such large areas of bright highlights, and purple fringing is unlikely to be such a problem.

F1.8, Nikon D300	F1.8, Nikon D300
100% crop, upper right	100% crop, top right

Background Blur ('bokeh')

One genuinely desirable, but difficult to measure aspect of a lens's performance is the ability to deliver smoothly blurred out-of-focus regions when trying to isolate a subject from the background. With its relatively fast maximum aperture, the 35mm F1.8G can produce substantially blurred backgrounds, and while these can be slightly hard-edged in character (especially at F1.8), bokeh is generally rather appealing. Stopping down progressively smooths out the harsher edges, with perhaps the best compromise in the region of F2.8.

F1.8, Nikon D300	F1.8, Nikon D300
50% crop, top right	50% crop, top right

Edge softness wide open

Our studio tests reveal a degree of softness with the aperture wide open, especially towards the corners, and here is our usual illustration of how this might appear in practice using the traditional boring brick wall approach. The loss in contrast wide open is quite visible, but as is often the case a high degree of fine detail is being recorded, albeit at this reduced contrast. Here we can also see the slight drop in brightness in the corner wide open due to vignetting; the top left crop also shows the increased visibility of chromatic aberration on stopping down. It's fair to say that when viewed in isolation, the F1.8 shot would look perfectly acceptable to most viewers; it's only when juxtaposing it against the F4 version that any deficiencies become visible.

F1.8	F4
Nikon D300, RAW + ACR
100% crop, centre of frame
100% crop, bottom right corner
100% crop, top left corner