Studio Tests - E 16mm F2.8 Pancake lens

The NEX system's second kit lens is the fixed-focal length 16mm F2.8 'pancake'. This is a tiny lens that matches the cameras' miniaturized body size very well, but as 24mm-equivalent wideangle, we think it's far from ideal as a general-purpose kit lens for Sony's stated target market (the compact camera upgrader).

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The 16mm pancake underwent something of a painful gestation, with some early sample shots that appeared on the internet looking far from satisfactory due to being shot using pre-production lenses. Sony tells us it has made changes to the manufacturing process which result in improved quality and consistency, and the results seem to bear this out. The lens is decently sharp across most of the frame even at F2.8 (although the extreme corners are distinctly blurred), and improves on stopping to give perfectly respectable results at smaller apertures.

Sharpness is very high in the center of the frame even at F2.8. It falls gradually towards the corners, and while most of the frame is perfectly acceptable, the corners are soft (particularly at the extremes, represented by the corner checkerboards but beyond our outermost measurement targets). Things improve on stopping down, with the corners picking up noticeably. The very best results are obtained around F5.6 - F8; apertures smaller than F16 are best avoided due to diffraction blurring.
Chromatic Aberration
Chromatic aberration is reasonably well controlled, and certainly no worse than the average kit lens or wideangle zoom. Red/cyan ringing is clearly visible towards the corner of the frame, but readily correctable in post-processing if required.
We consider falloff to become perceptible when the corner illumination falls to more than 1 stop less than the center. It's not at all bad here - about 1.3 stops wide open, which falls to about 1 stop at smaller apertures (but never quite goes away entirely).
Geometric distortion is, typically for Sony's recent kit lenses, quite high. Unusually for a wideangle it's of the pincushion type, and quite complex in character, with the center of the frame well-corrected but extreme stretching towards the corners.

Macro Focus

Wide primes rarely make great macros, and the 16mm is no different. Coverage is mediocre at best - our measured maximum magnification is just 0.09x, at a closest focus distance of 21.5cm (fractionally shorter than Sony's specified 24cm) giving a working distance of 17.5cm from the lens to the subject.

Image quality results in our flat-field chart test are nothing to write home about. Only the very center of the frame is sharp at F2.8, with the corners extremely soft. They sharpen up gradually on stopping down, but only come close to matching the center at F11 - F16. Pincushion distortion is clearly visible, and there's red/cyan fringing towards the edge of the frame.

Macro - 273 x 182 mm coverage
Distortion: Pincushion
Corner softness: High
Focal length: 16mm (24 mm equiv)

Specific image quality issues

Corner softness and chromatic aberration

Early pre-production samples of the 16mm F2.8 which were made available to journalists at the NEX system's launch clearly showed real problems, most notably poor corner sharpness and relatively high chromatic aberration. Now we have a production-quality sample, we can give potential buyers some idea of the image quality they should be able to expect from a lens they might buy in a shop. Roll your mouse over the labels below to see how the lens's sharpness changes with aperture in the marked areas of the frame (center, edge and extreme corner).

F2.8 F4 F5.6 F8

What we can see here is that the center of the frame is sharp at F2.8, but with a slight 'glow' or halo effect that disappears at F4. The edge of the frame is quite soft wide open, but sharpens up nicely by F5.6, while the extreme corner is distinctly soft at F2.8 and hasn't fully sharpened up even at F8 (of course this tiny section of the frame is unlikely ever to be important in real pictures). Red/cyan fringing from lateral chromatic aberration is also visible, most clearly in the edge crop.

This isn't the kind of output that will satisfy pixel-peeping purists, and clearly there's a price to pay for such a small, inexpensive wideangle. But it's also worth remembering that this is the type of lens you're likely to shoot at stopped down most of the time anyway, and the performance at the most commonly-used apertures (F5.6-11) should satisfy all but the most demanding of users. As usual there are plenty of examples to look at in our samples gallery.

It's also worth bearing in mind that the NEX-3 + 16mm lens combination is cheaper and more portable than most wide zooms for APS-C SLRs - let alone the cameras to put them on. Only Pentax offers a comparable prime, the 15mm F4 Limited, but it costs almost as much as the NEX-3 16mm kit and is a stop slower.

What's wrong with 16mm?

No doubt some of our readers will be wondering why we don't think the 16mm is the best choice for the NEX system at launch. Let's make it clear that we don't object to the lens at all per se; indeed we actually like the idea of having a compact wideangle prime to complement the kit zoom (arguably every system should have one). And, as wide primes go, the 16mm is really rather good in normal, everyday shooting. What concerns us more us is that it's being bundled with the bodies as the cheapest available kit, which is likely to tempt beginners to buy it in the promise of getting a portable, high image quality package for everyday shooting.

The problem here is that a wideangle prime like the 16mm isn't really a general purpose lens, but instead better suited to specific subjects - typically landscapes, architecture, interiors and the like. It's certainly not a great choice for photographing friends or family on a day out; because of its short focal length, that F2.8 aperture isn't going to give you significantly blurred backgrounds, and the inevitable wideangle distortion means anyone towards the edge of the frame will look unflatteringly fat. Overall it's certainly less capable an all-rounder than the fast normal primes available for competing systems, such as the Samsung NX 30mm F2, or the Panasonic 20mm F1.7 for Micro Four Thirds.

Because of this, we wouldn't recommend anyone buys the 16mm F2.8 as their only lens for a NEX unless they are absolutely sure they know what they are doing. Yes we know it's going to give the most compact, portable combination, but we'd advise against sacrificing function for form so dramatically. It would be great as the second or third prime for the system, it's just not an ideal kit lens.