Zeiss Vario-Sonnar T* 24-85mm f/3.5-4.5 N (Contax N to Canon EF) Review / Test Report - Analysis
Lens Reviews - Canon EOS (APS-C)

Distortion

The level of distortion is comparatively low within the tested APS-C scope. At 24mm the lens shows only moderate barrel distortion (~1.5%) and at 40mm and 85mm the issue is pretty much negligible.

Move the mouse cursor over the focal length text marks below to observe the respective distortion
24mm 40mm 85mm

The chart above has a real-world size of about 120x80cm.

Vignetting

The Zeiss is a full format lens and it shows only a very low degree of vignetting (< 0.5EV) at wide-open aperture (APS-C DSLR). This is negligible under field conditions.

MTF (resolution)

The Zeiss lens showed a very good and even resolution characteristic throughout its zoom range. The center resolution is generally very good at wide-open aperture and excellent beyond (till f/11) whereas the borders stay on a very good level. The peak performance is reached somewhere between f/5.6 and f/8.

Below is a simplified summary of the formal findings. The chart shows line widths per picture height (LW/PH) which can be taken as a measure for sharpness. If you want to know more about the MTF50 figures you may check out the corresponding Imatest Explanations

Chromatic Aberrations (CAs)

Chromatic aberrations (color shadows at harsh contrast transitions) are generally moderate for a standard zoom lens. As usual the lateral CAs are most pronounced at the wide end (0.7-1.5px at the borders). The problem decreases towards the long end of the zoom range and at 85mm the CAs are not field-relevant anymore.




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