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Sony E 16mm f/2.8 (Sony NEX) - Review / Lens Test Report - Analysis |
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Lens Reviews -
Sony Alpha/NEX (APS-C)
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Page 2 of 3
Distortion
The Sony lens produces a slight amount of pincushion distortion (~0.6%) which is usually not objectionable in field conditions.
Vignetting
The amount of light fall-off is fairly hefty at f/2.8 (~1.2 f-stops). This can be noticeable in some field images. Stopping down to f/4 and beyond eases the issue a little bit but it does never reach a negligible degree.
Update: These are the results based on a vignetting compensation. The native vignetting of the lens is in excess of 3EV at f/2.8!
MTF (resolution)
The Sony 16mm f/2.8 is a bit of an oddity in terms of resolution. Normally prime lenses are designed to outclass zoom lenses at their focal length but it seems as if Sony had different design priorities here. The lens is exceptionally sharp in the image center straight from f/2.8 onwards. That's the good news. The border performance is still good at max. aperture and it reaches very good quality at medium apertures. Now that's also promising. However, the corner performance is disappointingly poor - at f/2.8 there is no resolution to speak of and the corners are still very soft at f/4. If possible you should stop down to around f/8 which is the point where the corners can reach good results. Diffraction takes its toll from f/11 onwards. Field curvature (flatness of the focus plane) is pretty well controlled.
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)
Another weakness of the Sony lens is the amount of lateral CAs (color shadows at harsh contrast transitions). An average width of around 2px at the image borders is very pronounced especially for a prime lens.
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