Some sample images he
http://lcap.tistory.com/entry/Sigma-...mm-f18-Preview
An interesting lens for Dx users, and the samples look pretty good. (OK
- in my opinion, they look better than pretty good - they look great).

So this lens has four "glass-mould" aspherical elements. This is also
interesting, as even Nikon only seems to use "PGM" aspherical elements
in very high-end lenses, possibly explaining the exceptional performance
of the UWA 14-24 zoom. The aspheric elements, including the front
element, even on many "pro quality" (including some Canon L designation
lenses) wide lenses have been "hybrid" - glass laminated to plastic.

A harsh critic of Sigma recently has this to say about the Sigma 35mm f1.4:
http://www.lensrentals.com/blog/2012...ew-world-order
Tests at DXO show similar results for this lens.
Comments posted on Roger Cicala's blog indicate that users are having
problems with AF consistency on various bodies. A brief scan of forums
shows that many users are having AF consistency problems with fast
lenses of many different types and brands, so not sure if this reported
problem with the 35mm f1.4 is just another indication of the perils of
PDAF systems, high pixel counts, and aggressive pixel-peeping.
It will be interesting to see if adjustment using Sigma's USB dock can
overcome these focus issues if they are real. I suspect with fast
lenses on high MP bodies, that it's not going to be a simple DIY job to
calibrate AF when users have two systems to work on - the camera's AF
fine-tune as well as the lens calibration system itself.
Meanwhile, Sigma has issues with some "OS" lenses on some Nikon bodies,
but these are issues "unrelated to AF or lens performance", but weird
issues where an image being reviewed on the LCD screen on the camera
can't be "scrolled" when the OS system is turned on in the lens.

There's no price for the 18-35mm f1.8 yet. Sigma USA's "MSRP" when they
list new lenses is usually well above "street price" by the time stock
hits the stores.