Bad luck ?! - Update 2014 (2nd update)

It is pluck the hair: once seated the focus, sometimes not. Whether the central AF point or not. Whether AF-S or 3D.
I can not use in my job (People / Reportage).

Since Sigma does not respond to my emails, I'll try again to get a replacement unit.
I'm really disappointed, something I have never experienced in my work. As I said, if something sharpness sitting, it's great.

I must, however, be able to rely on my equipment.

PS: Before any brains think that working with fast lenses is a bit difficult, etc .:
I have a 35 / 1.4 Nikon had for one day out of the Rent - no problems!
I have a slow Nikon 50 / 1.4 - no problems!
I own a Nikon 85 / 1.8 - no problems!

Update February 2014:
So, I could not resist, I just need a fast wide angle for my work, because I almost always shoot at my reportage indoors. Since I am often stop at maximum aperture. The Nikon is too expensive as before and because I really want to have a 35er with 1.4er opening, no way around at Sigma.

So, again newly appointed, first disappointment: Lens was ever bolted on a bayonet and the front lens was also wiped ever - because the Sigma can not help it now, I know. Nevertheless crap that nowadays apparently "return" merchandise gets, although newly appointed ...

No matter, what matters is the result. For example, on my workhorse D800. In addition there is basically only one to say, when the focus point is properly seated, renders the lens (especially with maximum aperture), the images that it is an absolute feast for the eyes as well.
By that I mean that none of my other Nikon lenses as a "film" like, or sometimes provide almost 3D-like look.

I would love 28 / 1.8 and 24 / 1.4 Nikon see the mind ... However, we then talk about a different focal length range.

The only drawback so far: The autofocus (in continious mode) is quite the search in low light, and then is just sometimes be wrong something. Everything about it is always at maximum aperture: blurred. But I'm used basically from my other fast lenses, even more so at the bitchy D800. Have even with this lens extensively AF fine adjustment of the camera used and am first stayed with +8. In the mid to close range my correction at maximum aperture makes the most sense. Dimmed from about 6 feet sits the focus again is not quite right, but we'll see.

Somehow mistaken: because you really expensive work materials, working on site like a horse to produce reasonable images - just so the one then makes "Autofocus" a spanner in the works. The unfortunate part is yes, the camera gives a "green light", the image appears in the viewfinder of your subject and then the focal point is something behind and something in front of the object. Already have my camera with my lenses leave with my Nikon service test - Are you okay! Well. My D700 and before my D2X makes because no problems at all, but I digress and that's a completely different topic ...

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No question, this is a very nice, well-made lens. Moreover, it comes complete with hood and high-quality bag - at the relatively low price.

I am for ages Nikon photographer, currently with D700 and D800, and no sooner had I unpacked the lens and set to the D800, the theater was also going on already:

Autofocus does not and "rattles" attacks. Eventually he reaches and then exceeds times, or sometimes not. In any case, this is a defect and I have the lens (reluctantly) returned again. Whether this is due to lack of quality control, I can not judge, because Sigma now actually wanted to draw attention to themselves with premium lenses.

I'm not sure if I'll still buy another lens, because I can not use such adventures. So far, I didnt let sit no Nikon lens and so the disappointment is quite high. Schade somehow.