Originally Posted by Trondster
The numbers on the chart are pretty sharp - sharp enough that I'd say focus cannot be "way off," as you suggest. Rather, I suggest instead that the purple cast is truelongitudinal (axial)CA - the fact that stopping down progressively improves the fringing is consistent with that suggestion. In fact, a slight defocusing would actuallyimprovelongitudinalCA, rather than making it worse. Also note that this is a flat chart - we're not talking about 'bokeh fringing' here. As a side note, technically CA applies only in the plane of sharp focus, since by definition an aberration affects only what is in focus. But as the term is commonly applied, I'd call the fringing on both the Nikkor and the Zeiss lenses longitudinal CA, and not due to missed focus.
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