Review by Klaus Schroiff, published May 2007

Special thanks to Rüdiger Neumann for providing this lens for testing!

Introduction

The Sigma is an extremely compact lens at its 18mm setting - just 70x78mm. However, as you can see in the product images below above it extends significantly towards the long end of the zoom range and the included lens hood adds a few centimeters more. The lens uses a so-called duo-cam system with two inner zoom tubes to achieve this. As to be expected from a budget lens the mechanical quality can't be stellar but it remains actually surprisingly decent with no significant wobbling. The broad rubberized zoom ring operates a little stiff and slightly uneven whereas the focus ring feels reasonably smooth. Sigma implemented a zoom lock switch to prevent zoom creeping during transport (at 18mm only).

The lens has no internal AF motor and relies on a slotted drive screw operated by the camera. The AF speed and accuracy is generally fine although the AF struggles quite a bit in low light.