Large aperture standard zoom lens designed specially for use with digital SLR cameras. The characteristics of digital SLR cameras were taken into consideration when designing the lens power layout. The new advanced lens design corrects various aberrations. This lens provides the utmost correction against lateral chromatic aberration which is a serious problem for digital SLR cameras. This lens is specially coated to get the best color balance whilst cutting down flare and ghost caused by reflections from the digital image sensor and lens. It has excellent correction for vignetting and superior peripheral brightness is ensured. A Special Low Dispersion (SLD) lens and two aspherical lens elements provide excellent correction for all types of aberrations. The design produces a compact and lightweight, yet robust, construction with an overall length of 84.1mm (3.3in.) and maximum diameter of 74.1mm (2.9in.) and weight of 445g (15.6oz). This lens has a minimum focusing distance of 11 inches (28 cm.). It is equipped with inner focusing system. The non-rotating front lens element makes the lens suitable for using its petal-type lens hood and circular polarizing filters. It is an ideal large aperture standard zoom lens for digital SLR cameras featuring APS-C size image sensor.
1 Fantastic Lens!
This lens is soooo sharp. I returned a sigma 17-35mm EX DG HSM. The 17-35mm was a good lens with superb build. The 18-50mm f/2.8 is a great lens with good build. HSM would be nice and so would full time manual focus. Having said that. The focus is fast but not silent. However it is not loud either. And the auto focus is sharp, so I haven't had to use manual focus. It is so light that at first you think hey is the build cheap? No it isn't! It works well on my EOS 20D. If Sigma could make this lens 17-85mm they would sell a million of them. There is a lock for zoom creep but I never use it because there is no zoom creep. Oh yes the color and contrast are also great.
2 I like it on my 20D - compares well with Canon 28mm/2.8
I have a Canon 20D, and I have had these lenses:
Canon 50mm/1.8 (my reference standard for the best lens performance I can reasonably expect)
Canon 28-135 IS
Canon 28/2.8
Sigma 18-50/2.8
Canon 18-55 EFS
I have found that the Sigma 18-50/2.8 is the lens I keep on my camera most of the time. It has very good color, contrast, sharpness, saturation, and low distortion and aberration. By contrast to the 18-55 kit lens that came with my camera, the Sigma is in a whole different class. I would compare it favorably with my Canon 28/2.8 prime lens. I have never used a prime lens wider than 28mm, so I can't speak as to what the distortion is like at 18mm compared to a prime, but in general I am very pleased with the Sigma.
I find it has better dynamic range than the Canon 28-135 did; I can get better textures and ranges of intensity.
For the highest quality, I always go to my Canon 50/1.8, but in walking around and general shooting, I use the Sigma.
I was interested in the Canon 17-40L, but from what I have seen there is not a lot of difference in the quality from that lens and this one. Perhaps a little less distortion, but nothing you would notice unless you are taking pictures of brick walls.
