Carl Zeiss Sonnar T* FE 35mm f/2.8 ZA (Sony SEL35F28Z) - Review / Test Report - Analysis
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The Zeiss lens shows a slightly mustache-style distortion type which our tool interpreted as "pincushion". In any case it is marginal and very low for a wide angle lens.
The auto-corrected light falloff at max. aperture is very moderate for a lens on a full format camera. At f/2.8, we are seeing a light falloff of 1.3EV (f-stops). Stopping down doesn't help a lot with a best low value of just under 1EV. This remains visible in certain scenes.
The situation changes when looking at the uncorrected data. At fully open aperture, the falloff is a hefty 2.6EV. Stopping down to f/8 gives you 1.6EV which is still not good. Please note that the auto-correction effect is clearly visible in the image corners - due to the signal amplification they are more noisy than the image center. It is interesting to note that the RAW files are also touched when activating the auto-correction in the camera.
Generally the Zeiss Sonnar delivers the high resolution figures that we expect from a lens with the blue (Zeiss) label. The center performance is already tack sharp at max. aperture. The borders are very good here whereas the corners are slight softer. The corners improve substantially the more you stop down with a good to very good peak at f/5.6. Diffraction has a higher impact from f/11 onward but this setting remains easily usable.
The centering quality of the tested sample was good.
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)
The Zeiss lens produces a quite low amount of lateral CA (color shadows at harsh contrast transitions) of under 1px at the image borders. This is impressive on such a high resolution sensor.
The Zeiss Sonnar T* FE 35mm f/2.8 ZA delivers pretty good but not outstanding results regarding bokeh quality (out-of-focus rendition). Out-of-focus highlights have a circular shape at f/2.8 but the inner zone slightly nervous. This gets even more apparent the more you stop down. It is also somewhat disappointing that the aperture has an edgy shape at f/4 already.
On the positive side, the rendition in the critical focus transition zone is very smooth and buttery both in the fore- and background. This is a rare quality.
Bokeh Fringing / Longitudinal Chromatic Aberrations (LoCA)
Bokeh fringing is a common characteristic with fast glass. It's visible as halos of different colors in out-of-focus areas - magenta (red + blue) in front of the focus point and green beyond.
The Zeiss lens exhibits a significant amount at f/2.8 and it's even slightly visible at f/5.6. This is a bit surprising since the effect tends to be gone beyond f/4.
Move the mouse cursor over the f-stop marks below to observe the respective LoCAs