APO.chromatic: + Sigma 180/2.8 APO Macro DG HSM + Sigma 150/2.8 APO Macro DG HSM + Leica 180/2.8 APO-Elmarit-R + Voigtlander 180/4 APO-Lanthar + Nikon 70-200/2.8G VR II
- Sigma 180mm f/2.8 APO Macro DG HSM
- Sigma 150mm f/2.8 APO Macro DG HSM
- Leica 180mm f/2.8 APO-Elmarit-R
- Voigtlander 180mm f/4 APO-Lanthar
- Nikon AF-S 70-200mm f/2.8G ED VR II
Also documented is focus shift, with some surprising findings.
A variant of this comparison minus the Sigma 150/2.8 is presented in Guide to Leica.
The test scene was set up specifically to ferret out secondary longtinudinal chromatic aberration in particular, but also lateral chromatic aberration.
An apochromatic lens should greatly reduce or eliminate both longitudinal chromatic aberration (LOCA) and lateral chromatic aberration (LCA). As related bonuses, it should also minimize secondary longitudinal chromatic aberration, spherical aberration and spherochromaticism. See Optical Aberrations in Making Sharp Images.
There is no marketing definition for “APO”, nor does the term guarantee better performance than a lens lacking the APO designation. Each vendor is free to correct for color to the extent deemed appropriate and to apply or not apply the APO term to its lenses. For example, many Canon and Nikon lenses with special types of glass (“ED” and fluorite) would quality for the APO label, but Canon and Nikon choose not to do so.