Canon

http://slrgear.com/reviews/showproduct.php?product=1804

Sharpness 
Sigma is on a roll when it comes to sharp lenses. Like other recent Global Vision lenses we've tested, the Sigma 24-35mm certainly does not disappoint in this area!

On full-frame cameras, even wide-open, the Sigma 24-35mm produces sharp, very sharp, images. At 24mm ƒ/2.0, we must concede that while the center region is nearly tack-sharp, there is some softness in the corners, which isn't all that surprising to be honest. Stopping down a bit sharpens thing up considerably in the corners, and by ƒ/4.0, things are practically razor sharp across the whole frame.

At the other focal lengths, we measured similarly sharp centers and slightly softer corners at ƒ/2.0, though the center region at 24mm measured sharper over a wider area of the frame compared to the other focal lengths. Overall, though, wide-open performance is great at all focal lengths, which is what we were hoping for.

Stopped down, the Sigma 24-35mm also displays impressive performance when it comes to sharpness. We found ƒ/4.0-5.6 to be the "sweet spot" for critical sharpness at all focal lengths we tested, with the most corner to corner sharpness. We did measure a slight increase in softness as you stop down past this point, but the impact on image sharpness is very minor. Even diffraction-related softness is extremely minor by the time the lens is stopped down to its smallest aperture of ƒ/16.

When mounted to a sub-frame camera, we also found excellent sharp results, even wide-open. As expected, though, the wide-open corner softness experienced when using a full-frame camera is significantly reduced when using a sub-frame -- there's still some corner softness at ƒ/2.0, but it's very minor. Sharpness overall, however, throughout the focal length range is very impressive, with nearly tack-sharp images at practically all apertures, especially between ƒ/4.0-ƒ/8.0. Diffraction barely takes a toll on image sharpness at the very small apertures, either.

요약:개방에선 중앙부는 전 초점 거리에 걸쳐 선명하고 주변부는 약간 소프트하다.조이면 주변부도 선명해진다.f4-5.6이 가장 선명하다.

Conclusion 
We think Sigma has done it again! Sigma once again dares to be different and builds a unique lens not offered by the major manufacturers. In what is essentially a range of fast prime lenses built into a single zoom lens, the new Sigma 24-35mm is stunning with super-sharp images, even when shot wide open. Combined with its fantastic build quality and excellent AF performance, the Sigma 24-35mm ƒ/2.0 Art lens is a great option for street shooters, concert and event photographers, even landscape and astrophotographers; or just about any full-frame DSLR owner looking for stunning sharpness and excellent low-light performance.

시그마는 시그마 자신에 대항해서 다른 메이커에서 제공하지 않는 새롭고 독특한 렌즈를 만들어내었다.빠른 단렌즈의 일정 범위를 줌 렌즈 하나에 집약시켰는데 시그마 24-35mm는 아주 샤프한 놀라운 이미지를 제공한다.아주 우수한 만듦새와 탁월한 AF의 조합으로 시그마 24-35mm f2는 놀라운 샤프니스와 탁월한 저광량 성능을 원하는 거리 사진가.콘서트 사진가,심지어 풍경 및 천체 사진가,또는 모든 풀 프레임 DSLR 소유자들에게 아주 좋은 선택거리를 제공한다.