There are a lot of bad reviews about this lens. It does have it's flaws, but overall it is great wide angle lens for the price. I was in the market for as wide of a lens as I could find around the $500 price mark. And this what I took a risk after reading multiple bad reviews.

Heavy vignetting, soft in the corners, but it's a good little lens if you are looking for something on the wide end.

The optical construction is made of 11 elements in 9 groups without any special glass. The aperture mechanism features 5 blades. With a min. focus distance of 0.25m the max. object magnification is about 1:7. The lens feature a floating system for close focus correction.