Sigma

Sigma produces lenses and electronic flash units.

Quality

Sigma lenses in the EX series is generally good quality and in some cases excellent value for money. The quality control is not the best and it is not uncommon to find bad lenses. The lenses feel sturdy but is generally quite heavy.

Sigma for Canon

There are often compatibility issues when Canon releases a new camera. If the lens is under warranty or if it is still in production then Sigma seems to upgrade the lens for free. There has been some reports about lenses that focus in front or behind the subject.

Sigma for Nikon

There was an incompatibility issue with Nikon D200 but it was fixed by Nikon in a firmware upgrade to the camera. There has been some reports about lenses that focus in front or behind the subject but it seems to be less common than for Canon.

Sigma lenses tested on Nikon

10-20mm f/4-5.6 EX DC HSM

Extremely wide angle zoom with good autofocus. Some distortion in the corners but very good in general.

30mm f/1.4 EX DC HSM

Excellent centre sharpness, not very sharp in the corners. The autofocus is a bit hesitant and is not always spot on. Not good for landscape use when full frame sharpness is important. Very good for artistic and low light use.

150mm f/2.8 EX DG HSM

Big and heavy macro lens that gives excellent picture quality, it is also usable as a telephoto lens. The Hyper Sonic Motor (HSM) gives acceptable focus speeds even when not used as a macro. Because of the focal length it is hard to use hand held as a macro and flash is also a must when working hand held.