I'm looking to upgrade from my kit lens and I'm torn between these two. My instinct is to go with the 17-55 because it's a faster lens and I do a lot of indoor, low-light shooting. My hesitation is that when comparing the two lenses in the ISO 12233 test, the 15-85 looks far superior across the frame in sharpness, contrast, vignetting and CA:


http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?CameraComp=0&FLIComp=0&APIComp= 0&Lens=398&Camera=474&Sample=0&FLI =0&API=0&LensComp=675


When I read the respective reviews, the 17-55 is regarded as having slightly superior image quality. Am I missing something? Any advice appreciated!


Canon T2i body, 18-55 kit lens



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