12-35 unimpressive as a landscape lens

I think 12-35 is optimized to shoot wide open at f/2.8, and when you shoot wide open with shallow DOF, corner performance is not that important.

I have both 12-35 and 35-100 and I simply love them.  I mainly photograph people, almost never stop down past f/4.  I understand you and I have different needs.

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Just Shoot !