|
Zeiss Distagon T* 25mm f/2.8 ZF - Review / Test Report - Analysis |
|
Lens Reviews -
Nikon / Nikkor (APS-C)
|
|
Page 2 of 3
Distortion
The Zeiss 25mm f/2.8 ZF produces a moderate degree (1.1%) of barrel distortion.
This is about in-line to what we´ve seen from other manufacturers.
The chart above has a real-world size of about 120x80cm.
Vignetting
The Zeiss lens exhibited a relatively steep vignetting of 0.94EV at wide-open
aperture. While this is no worse than the corresponding Nikkor it is still
a bit disappointing for a brand new full-frame lens tested in the APS-C scope.
From f/4 onwards the problem is negligible under field conditions.
MTF (resolution)
Similar to the Zeiss 50mm f/1.4 the Distagon produces breathtakingly high
center resolution figures straight from the max. aperture setting. At f/4 and
f/5.6 the center quality matches or exceeds the limits of the 10mp D200
sensor. However, the border performance isn´t quite as impressive. At f/2.8
the quality is very good (just) but increases steadily till about f/8. At
f/11 diffraction is the limiting factor thus resulting in a decrease in
quality (this is a physical limitation).
Please note that the MTF results are not directly comparable across the different systems!
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
moderate both in absolute terms as well as compared to other wide-angle
lenses. The average CA width varies around 1 pixel at the image borders.
|
