Review by Klaus Schroiff, published September 2011

Introduction

The fairly moderate pricing certainly also helped to contribute to the success. Now good things can always get better and Sigma felt the need to provide a successor - the Sigma AF 12-24mm f/4.5-5.6 HSM DG II - which takes advantage of their latest generation glass technology (FLD elements). Keen readers may have noticed a slight difference in the product naming. The mk II is no longer a designated EX ("Excellence") lens - "EX" identifies professional grade products by Sigma standards. This is a bit of a mystery because neither the basics specs nor the pricing have really changed. We suspect that Sigma may have decided to use "EX" exclusively for constant aperture lenses.

Anyway, the build quality of the Sigma lens is very high thanks to a tightly assembled combination of plastic and metal parts based on a metal mount. The zoom and focus control rings feel slightly stiff but therefore also very precise. The physical length of the lens remains constant at all zoom and focus settings although the inner lens tube moves a little. A non-detachable petal-shaped lens hood does not only help to combat sided light but it also protects the vulnerable "bulb-like" front element from scratches. The two-part lens cap can be slipped over the metal lens hood. The front cap can be removed and allows to mount a filter to the base unit of the cap. However, this makes rather limited sense because even the base unit will already produce vignetting throughout most of the zoom range.

Typical for most Sigma lenses, the AF mechanism relies on a "Hypersonic Motor" (HSM) which is both fast and nearly noiseless. The AF precision of the tested sample was just soso which may not even be a limitation of the lens but rather the camera which suggested near-infinity focus settings most of the time. This is not really desirable anyway though because you are wasting lots of depth-of-field potential but more on this later.