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Sony E 18-55mm f/3.5-5.6 OSS (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 18-55mm OSS exhibits a fairly hefty amount of barrel distortion at 18mm (~4%). There is basically no distortion at 24mm but the characteristic turns to moderate (~2.1%) pincushion distortion at 35mm and slight (~1%) pincushion distortion at 55mm.
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Move the mouse cursor over the focal length text marks below to observe the respective distortion
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| 18mm |
24mm |
35mm |
55mm |
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Vignetting
The vignetting characteristic is a bit on the odd side. There's a basically constant amount of light fall-off at 18mm. This is highly unusual so we suspect an automated vignetting compensation "under the hood" (inc. RAW). At around ~0.7 f-stops the problem may be just noticeable in critical scenes but it's usually nothing to worry about at such a wide setting. Vignetting is a non-issue from 24mm onwards.
Update: It is, by now, obvious that these figures show the results with vignetting auto-compensation!
MTF (resolution)
The Sony lens produced decent resolution figures in the MTF lab. The center resolution is generally excellent till f/8 and the border quality varies around the good-to-very good (just) barrier - this characteristic is kept across the focal length range although there's a slight dampening at 55mm. Diffraction effects start to have a stronger negative effect beyond f/8. The centering quality of the tested lens wasn't great.
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 CAs (color shadows at harsh contrast transitions) are a weak spot of the Sony lens. The issue is very pronounced at 18mm and 35mm at medium aperture settings and easily visible in images. Interestingly lateral CAs are not much of an issue at 24mm and 55mm.
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