Zeiss Planar T* 85mm f/1.4 (Contax N to Canon EF) - Review / Test Report - Analysis
Lens Reviews - Canon EOS (APS-C)

Distortion

The Zeiss T* 85mm f/1.4 produces a negligible degree of distortion (~0.2%) which is not field-relevant.

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

Vignetting

The Zeiss lens exhibited the typical vignetting characteristic for full frame, ultra-large aperture tele lenses used on an APS-C DSLR. At wide-open aperture the vignetting is moderate at around 0.7EV. Starting at f/2 the problem is negligible under field conditions.

MTF (resolution)

The Zeiss lens showed impressively high resolution figures although it does not match the EF 85mm f/1.2 USM L here. The center performance is already very good at f/1.4 and excellent beyond. However, the border quality isn't quite on that level specifically at large apertures. At f/1.4 the borders are fairly soft and stopping down does gradually improve the resolution figures to very good levels by f/2.8 and up to an excellent peak at 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 very moderate with an average pixel width around 0.3px at the image borders. This is not field-relevant.

Typical for many ultra-large aperture lenses the Zeiss also shows some Longitudinal Chromatic Aberrations (LoCA) resulting in greenish and reddish out-of-focus edge transitions.




© by photozone.de