Chromatic aberration is a type of optical distortion and is a separate issue to color rendition. Color rendition refers to the lens's ability to transmit light equally across the color spectrum. If the lens is more transparent to red wavelengths than blue, images will look warmer, for example. Chromatic aberration, on the other hand, is a type of distortion in which a lens fails to focus all colors to the same convergence point. It will negatively affect image quality even if you use the lens to take black and white photos, since the result is a blurrier image.