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Zeiss Planar T* 85mm f/1.4 ZA ( Sony SAL-85F14Z ) - Review / Test Report - Analysis |
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Lens Reviews -
Sony Alpha/NEX (APS-C)
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Page 2 of 3
Distortion
Typical for fix-focal length lenses in this range there're virtually no significant distortion
to worry about (0.2%).
The chart above has a real-world size of about 120x80cm.
Vignetting
The Sony 85mm f/1.4 is a full format lens and as such enjoying the usual sweet spot advantage
when used on an APS-C DSLR. Within this scope the lens shows a little vignetting at f/1.4 (0.5EV)
but this isn't really something to worry about in field conditions. The problem is absolutely
negligible by f/2.
MTF (resolution)
The Zeiss 85mm f/1.4 ZA produced superb resolution figures in the MTF lab. At f/1.4 the quality
is already exceptionally high for such a lens and unlike e.g. the Sony 50mm f/1.4 the contrast level
is perfectly usable. It's not really a primary aspect for such a lens but the center to border
resolution is very even. Stopping down lifts the resolution level a little and
the peak is reached around f/4. Interestingly the 50mm f/1.4 is a little sharper in the center
but this is nit-picky.
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)
Lateral chromatic aberrations (color shadows at harsh contrast transitions) are very well controlled
with an average pixel width around 0.4px at the image borders. Generally this is nothing to worry about.
Bokeh
The quality of the bokeh is naturally of major interest for an ultra-large aperture lens and the
Zeiss does not disappoint here.
Out-of-focus highlights show a circular shape from f/1.4 up to about f/2.8. At f/4 the shape
deteriorates a little. There's basically no outlining effect here - this is about as good as
it gets in lens land. The blur is very smooth and uniform. However, you may also notice the
rather massive amount of longitudinal chromatic aberrations in the cards - more on this in the
next chapter.
You can download the full-size images here:
Longitudinal (Axial) Chromatic Aberrations (LoCA)
LoCAs (non-coinciding focal planes of the various colors), sometimes called "bokeh CAs", can be a problem
in the field. Similar the Canon 85mm f/1.2 USM L and Nikkor 85mm f/1.4 the Zeiss does also suffer
from this optical defect. As you can notice below the halos have different colors - magenta
(red + blue) in front the focus point and green beyond. The problem is rather pronounced at f/1.4.
It decreases slowly the further you stop down but it is still visible at f/4. The Zeiss 135mm f/1.8 ZA
is probably a little better here thanks to its 2 ED elements - the ZA 85mm f/1.4 is a more conventional
design.
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Move the mouse cursor over the f-stop marks below to observe the respective LoCAs
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| f/1.4 |
f/2 |
f/2.8 |
f/4 |
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