from just slightly inside the door frame with ease because of it. I can do walk-in closets, personal elevators, small bathrooms, laundry rooms, etc.
It really adds to your flexibility as to where you can shoot from. I do residential interior and exterior real estate photography too and I can tell you FOR A FACT that after you have that extra 8 and 9mm available you won't regret it and will wonder how you ever lived without it. That's a hassle so I just have presets in Lightroom and Photoshop to do it a slight bit less accurately but almost indistinguishable from DxO. I also have DxO Optics Pro 8 which has a profile for this Sigma lens but I don't really like jumping out of my workflow to put shots through it. In Photoshop ACR I created a lens profile for the Sigma and made that part of a preset I use on every photo out of that camera. The vignetting is fairly bad though and in Lightroom I have to increase the slider to 40 to correct it. I straighten it in Lightroom and Photoshop ACR rather easily. You can't actually expect it to be perfect at 8mm. The aspherical 8-16mm's barrel distortion isn't nearly as bad as a fisheye lens but it's not perfect. I did wonder about the distortion at 8mm though. But the 8-16, for the extra coverage, had begun to look interesting. Actually, I have been leaning more to the Nikon 10-20. I have been using the Sigma 10-20 f4-5.6 for the past 5 years and was considering either the f3.5 model or the Nikon 10-20.
It is worth noting the level of sharpness, which I don't think can be equaled (especially in the corners) by any other UWA. The first is shot at f4.5 (wide open), the second at f7.1. I'm posting a couple of test shots I did when I first got the lens. Worse, as it were, is the fact that you get very converging verticals and stretched corners. It does have some distortion, which is not terrible, but it is complex.
The Sigma 8-16 is significantly wider at 8mm than the 10mm of the other lenses. To be fair, it is only at 10mm and only the very corners, but at no aperture do they every really get very good. The Nikon 10-24 is absolutely decent, and has the best flare resistance of the lot, but it has one major weakness, which is again soft corners. Stay away from the f3.5 if you shoot at 10mm-the corners are atrociously soft wide open, and it takes getting to around f8 before they are decent. I thought the 10-20 4-5.6 was pretty decent, but I was unhappy with the softish corners and the CA, as well as the general flare characteristics.