I have to say I was a little nervous about purchasing this lens. My only other experiences with Tokina were their 11-16mm and I bought them to rave reviews and returned them after use. Deep down in some reviews, which I didn't notice at the time, there was a huge field curvature, starting at 14mm and peaking at 16mm. Of course the center was very sharp, but the offset of about 2/3 was terrible. I needed a wide angle that was consistently sharp throughout the zoom range from corner to corner (not the small legs, of course). I have a Sigma 10-20 f4-5.6 and while it was consistent it wasn't the sharpest. Sure, you can get some really good shots, but where the fine details matter, the flaws show. I was considering the Samyang 16mm f2.0 as I have a 14mm and wow it's a great lens but I didn't want to invest thousands in multiple filters for the Wonderpana system. I have their polarizer and it works fine. The new Tokina 11-20 piqued my interest, but the curvature of the field of view bothered me and the 82mm filter thread got me thinking about this lens. I have to say that the lens rating is pretty accurate. If you don't like the dreamy soft look, f4 is useless. Stop at f5.6 and there will be a wonderful transformation, very abrupt. Stop at f8-11 and it gets sharp from corner to corner. It's almost as sharp as the Samyang 14mm, though not quite. Sharpness appears to be consistent throughout the zoom range. So if you're shooting with flash, outdoors, or on a tripod, this is a great lens. If you need a manual low-light lens, look elsewhere. By the way, I noticed chromatic aberration at f4 and less at f5.6. Essentially it disappeared on f8. There is almost no vignetting. In fact, compared to the Sigma, you can see how badly this lens vignettes. My copy required a micro setting of -20 to be sharp, so cameras without this option should test the lens thoroughly to ensure it will work well with your particular camera before deciding to keep it.
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