Zeiss Makro-Planar T* 100mm f/2 ZF (FX) - Review / Test Report - Analysis
Lens Reviews -
Nikon / Nikkor (full format)
Tuesday, 27 January 2009 19:29
Page 2 of 3
The Makro-Planar is capable of producing distortion free images. This is impressive albeit quite typical for macro lenses.
The chart above has a real-world size of about 120x80cm.
The Zeiss lens has its share of vignetting problems when used on a full format camera. At 1.3EV @ f/2 the problem is fairly obvious but it's actually not worse than the results by its competitors at f/2.8. Stopping down reduces the issue and it's not field-relevant anymore from f/4 onwards.
We're performing our vignetting analysis based on
(uncorrected) JPEGs straight from the camera. The JPG engine of the Nikon D3x features a rather flat
gradation curve, thus has a moderate contrast characteristic, resulting in comparatively low vignetting figures - the
corresponding Canon figures are roughly 40% higher due to the more
aggressive default contrast setting.
The Zeiss lens produced superb resolution figures in our MTF lab. The center resolution is already exceedingly sharp at f/2 and the borders/corners follow on a very good level. The global peak performance is reached at f/5.6 with an excellent quality across the image frame. Diffraction effects have a higher impact from f/11 onwards but the quality is still very good at f/16 in the image center. Field curvature is a non-issue.
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
Chromatic Aberrations (CAs)
Chromatic aberrations (color shadows at harsh contrast transitions) are extremely well controlled and not field-relevant.
The bokeh (the quality of the out-of-focus blur) is a primary aspect for an ultra large aperture lens and the 100mm f/2 does not disappoint us here - mostly. The blur is very smooth and buttery. Out-of-focus highlights are rendered very well at f/2 and f/2.8 although the shape is not perfectly circular but a bit "cat's eye"-like (due to mechanical vignetting). If you stop down to f/4 and beyond you may spot some more angled highlight "discs" if you try hard enough.
Bokeh fringing at large aperture is a problem which is often not well corrected even by the very best lenses and the Makro-Planar is no exception to the rule unfortunately. If you have a look at the provided sample crops below you should be able to spot a purple halo in front of the focus zone and a green one beyond. The effect is clearly visible from f/2 till f/5.6, less so beyond.