The new 16mm Sigma lens is now shipping in EU and USA at Wex UK, Amazon Germany, BHphoto, Amazon and Adorama.
DPreview is testing the new Sigma 16mm f/1.4 MFT lens and writes:
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.