A closer look at the Sigma 16mm F1.4 DC DN for Micro Four Thirds
We've got a pair of Sigma 16mm F1.4 DC DN lenses in the office: one for Micro Four Thirds and the other for Sony E-mount. In this article we have some impressions of the MFT version, as well as some other lenses in this class worth considering.
The 16mm F1.4 acts as a 32mm equivalent lens on the Micro Four Thirds platform. It's an interesting focal length to end up with: not quite 28mm equiv., which many people would consider the gateway to wide-angle, but also noticeably wider than the near-normal of 35mm equiv. I didn't expect it to make any difference but found myself constantly fighting against too much stuff creeping into the edges of the frame in a way that I don't with a 35mm.
In terms of handling, I felt the 16mm worked best when mounted on the larger Micro Four Thirds camera that feature prominent hand grips: its comparatively long length feeling a little unbalanced on the smaller, rangefinder-style boxes, though it's light enough that it doesn't end up feeling too front-heavy. The lens's only control point is a large by-wire focusing ring. It's a little under-damped for my tastes, rotating fairly freely but it was effective on the few occasions I ended up having to manual focus (turns out LED Christmas lights and autofocus do not always play nicely with one-another).
Optically, I was pretty impressed with the lens, the F1.4 (F2.8 35mm-equivalent) aperture gave me plenty of control over depth-of-field and sufficient light for low-light work. Sharpness seems good if not necessarily stellar and with what appears to be pretty good cross-frame consistency, until you reach the extreme corners. As you'd expect, the performance gets better if you stop down a couple of notches. The 16mm is pretty resistant to flare, even when given significant provocation, with good levels of contrast maintained even in contre jour images with veiling flare.
Autofocus was snappy to the degree that I didn't ever really have to think about it. Only the aforementioned Hybrid AF/LED Christmas light mismatch caused me to even give it a second thought. It's fast and quiet to the degree that you just don't notice it, and can concentrate on composing your shot instead.
My impression is that the Sigma is sharper, two thirds of a stop faster and comparably priced to the Olympus 17mm F1.8. However, I don't think it's quite as easy a win as that makes it sound. The Olympus is significantly smaller and features the lovely snap-back manual focus clutch and linear manual focus system (faux-cus by wire, perhaps?), both of which are definite bonuses. So, while I'd find it hard to choose between the two, I probably wouldn't rush out to replace a 17mm if I had one, not least because I personally prefer the narrower angle-of-view that the extra 1mm brings.
1mm in the opposite direction is the Panasonic 15mm F1.7. It usually retails for around $100 more than the Sigma, despite being rated as half a stop slower. Again it's smaller than the Sigma, meaning it handles better on a smaller camera body. Similarly, the 15mm offers a neat operational advantage over the DN, at least for Panasonic shooters: the lovely Leica M lens style front aperture ring (worth the extra $100 on its own, in my opinion and well worth lobbying Olympus for firmware support for, if you're on that side of the system). Optical performance is perhaps a step up from the Sigma, leaving the 16mm F1.4 DN DC as an attractive extra option for Micro Four Thirds but not an absolute must-have, from my perspective.