* Vignetting always improves
* First-order distortion improves, second-order distortion sometimes gets worse.
* Corner sharpness usually improves, unless midway out on the frame was the weakest performance on full frame.
* Center sharpness (image-scale) drops due to the additional enlargement.
* Lateral chromatic aberration generally doesn't get significantly better or worse.
* Longitudinal chromatic aberration becomes more visible because of the additional enlargement.
* Vignetting always improves
* First-order distortion improves, second-order distortion sometimes gets worse.
* Corner sharpness usually improves, unless midway out on the frame was the weakest performance on full frame.
* Center sharpness (image-scale) drops due to the additional enlargement.
* Lateral chromatic aberration generally doesn't get significantly better or worse.
* Longitudinal chromatic aberration becomes more visible because of the additional enlargement.