Sigma Lens got it right,
The Sigma 18-200mm incorporates an Optical Stabilizer function and is exclusively designed for digital SLR cameras. We’ve been using this Sigma 18-200 for a couple of months now. Recently we compared the Sigma with Canon’s 28-135mm image stabilized digital slr lens on a Canon 30D. We shot side by side photographs at 28mm & 135 mm both, set to ISO 100 with camera in Program mode. Our lenses sigma were set to autofocus with image stabilization on.
The good news which I really didn’t expect was to see both sigma lens produce images that were nearly identical– I thought for sure Canon’s optics would far surpass Sigma’s. Color saturation, light exposure through the 18 200mm, and detail were indistinguishable. The autofocus worked equally well on both. Both weighed about the same and were about the same size. The Sigma has a 72mm diameter aperture which I liked (so does the Canon). Of course the Sigma is 18-200, and at this time Canon does not have a competing option in the same digital SLR lens class with image stabilization.
The only aspect of the Sigma that differed significantly from Canon’s lens was the noise of Sigma’s autofocus motor. Sigma produces noticeable motor noise, though it wasn’t overly loud. Still if you were shooting in a spot where silence was critical such as a ceremony, it may become an issue but probably not. In comparison, the Canon autofocus motor is silent and fast every time.
Sigma places a locking mechanism on the lens barrel to eliminate any possibility of lens creep (lens extending when pointed down). I doubt this would be a problem with the Sigma anyway. The zoom ring is a little stiff, but not too stiff. The manual focus ring is designed to be used with AF set to off to avoid manipulating the motor when focusing.
The image stabilization works well allowing you to shoot lower light photos without a tripod. I was quite satisfied with Sigma’s newest effort here.
I’d say this Sigma makes a great choice for amateur photographers like us looking for a single lens option on Canon digital SLR cameras. The only dissuading factor ‘might’ be the motor noise if you hope to match Canon’s silent motor system. Until Canon produces the same class of lens at a competitive price, Sigma has this round sown up. .
