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| p.1 #4 · p.1 #4 · when sagittal and tangential Spatial frequency curves don't coincide |
I wouldn't call the curves for the 18 mm f/3.5 Distagon horrendous (a 100-degree angle of view is hard!), but I see what you mean. In this case, since the tangential curves don't greatly improve when going from full aperture to f/8, you can guess the lens probably has significant lateral chromatic aberration. You can see this in real-world photos, too. Other aberrations are no doubt present in addition to lateral chromatic aberration.
The 100 mm f/2 Makro-Planar has very low lateral chromatic aberration. Longitudinal chromatic aberration is also pretty low, allowing nice MTF curves at f/2 for white light. That doesn't mean the lens doesn't produce false colour in out-of-focus regions, which might be what you're thinking about. Modern lenses with a good correction of the monochromatic aberrations often produce saturated false colours just outside the focal plane. This can be caused by wavelength-dependent spherical aberration (spherochromatism), which is ironically made worse by the strongly curved lens elements used to correct other aberrations.
Bottom line: if you'd like to know how the lenses perform, look at photos produced by them! The MTF curves don't reveal everything.