Tamron 17-50 OR Canon 17-85mm?

By the initial tests release the new 18-135 IS STM appears to be much better than the original 18-135 IS: http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=809&Camera=736&Sample=0&FLI=0&API=0&LensComp=678&CameraComp=0&FLIComp=0&APIComp=0

Well even at least with the original 18-135 IS stopping help improve its center-to-edge performance. One of the cons of the 17-85 IS is stopping down did not improve edge sharpness much.

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