But the Zeiss Batis 40mm f2.0 CF is very good in this respect: it shows very little loCA even wide open. These normally show up as magenta coloration in the foreground and greenish hues in the background and are not easily corrected in post-processing. Lenses with focal ratios of f2.8 or larger are often prone to longitudinal color aberrations (loCA, a.k.a.
Testing: Longitudinal Chromatic Aberration and focus shift