Unfortunately, the Tokina difference due to its limited zoom range from, it's almost a UWW fixed focal length, and I wanted to or simply need a little more flexibility in this focal length range.
The Canon finally retired due to its higher price, without providing appreciable performance while climbing conclusions from.
Now for the experience that I have made with the Sigma.
The lens is processed perfectly, and in my experience you get in this area from any other manufacturer such processing quality offered like the Sigma EX lenses. Although I also have to clearly point out that for me to come only from the EX series lenses from Sigma for me in question. I've had several opportunities to test the cheaper Sigma offshoots, and so far could not really convince them, both by performance and the feel of her (exception is the 8-16mm, in which it is a mystery to me why there is no EX scored branding '). This lens zoom and focus ring run as smooth as silk, it rattles nothing and it engages with a rich sound perfectly into the bayonet. Furthermore, I am a great friend of the Sigma Finishes become, I like the slightly rough, rubberized feel of the EX Series significantly better than the smooth finish of Canon lenses (very subjective).
A lens can still be processed so perfectly that what it is ultimately measured, its optical performance. After about 700 pictures with this lens, I can issue him here a very good report, even much better than I would have expected beforehand. First, I tested the lens on brick walls, etc. to form a first impression of the possibilities to get here already hid the first surprise, even the corners are easily available, although you can at a 100% magnification a slight drop compared to the image center make up, but in actual use is not visible.
Flares occur as well as not on, only Ghosts occur when one takes the (bulging) sun at the edge of the image. But this is my experience, no worse than the other competitors, because Ghosts actually occur in such situations at all UWW lenses.
Chromatic aberrations do not occur even virtually, and then only very slightly, so I had to really look for it in 100% magnification. So here I also would preclude influence on the picture quality in practice.
The only point on which you have to indicate clearly in the Sigma, is the fact that it is relatively weak light. With an initial aperture of 4 at 10mm and 5.6 at 20mm, you will encounter quite at borders, if one uses the lens in low light. Here I refer to the Sigma 10-20mm 3.5, that with his constant aperture is also a very interesting objective, but in the end I was personally too expensive.
What you always have to point at the EX Series lenses from Sigma, is supplied. In particular, as opposed to Canon this is exemplary here! In addition to the lens itself you get the appropriate lens shade and a very nice lens case, which protects the lens is also good and not only a small bag is. This is followed by others may well take an example!
The lens is designed exclusively for sensors cameras with APS-C, and if you put it on small screen converts to a 16-32mm (Canon) or 15-30mm (Nikon, etc.) lens, and is thus quasi the Crop equivalent to the classic reportage-wide-angle lenses on full-frame / film cameras. I had put it on a tour in the tsunami-devastated areas of Japan with this, and can it ideally suited to tell each other stories. Such a lens just gives me the opportunity to represent my subject with its environment and therefore to tell a story.
In conclusion I would like to say that I am very happy with the lens. It is characterized by a very good image quality and workmanship, and is above all a very versatile lens. Be it landscape photography, reportage, event photography almost everywhere it can be dropped. Only one should be careful that there is sufficient light. To this end, still a little note, you should check whether the system flash can zoom out to 16 / 15mm, because if one wants to use one, because, unfortunately, some go so far.
I hope I could be a little help with this Rension.
