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This is my test of the CV15 with a NEX-5N.
I did it putting a white traslucent disc over the lens and aiming the camera to the sky, The white balance was customized for that light, in order to get a neutral colored center of the frame. Focus was at infinity.
As you see there's a noticeable, but not unbearable, color shift. It's blue-purple on the right side and somehow on the lower left, changing to blue-cyan on the upper left.
I tested also the lens at f/5.6 and f/8 but the results were essentially the same concerning color shift although the luminance vigneting was lower.
It's also probable that a different copy of the lens would perform a bit different, (purplish left sides and bluish on the right, for instance ).
IMHO, usually there's no need to apply Cornerfix for landscape work. Those deeper colored corners sometimes adds a pleasant effect to the pictures