Olympus Digital Zuiko 40-150mm f/4-5.6 ED Review / Test Report - Analysis
Lens Reviews - (Micro-)Four-Thirds

Distortion

Just like most other tele zoom lenses the Zuiko is capable of maintaining a a fairly low level of distortion throughout the range. At 40mm it produces moderate barrel distortion (~1.4%) which changes to slight pincushion distortion towards the long end of range.

Move the mouse cursor over the focal length text marks below to observe the respective distortion
40mm 100mm 150mm

Vignetting

Vignetting is quite well controlled for such a lens. In very critical situation you may spot a hint of edge shading but at around ~0.6EV at wide-open aperture it's generally not an overly relevant issue in field conditions.

MTF (resolution)

The resolution characteristic of the Zuiko is quite good but it does not stretch the peak resolution of the today's sensors. The center performance is generally very good at 40mm and 100mm and the border quality is just slightly worse. At 150mm the lens suffers from a slight drop in center performance but even so it remains perfectly usable here.

Please note that four-thirds cameras have a different diffraction characteristic than APS-C or full format cameras. The real-world sweet spot, the point of highest resolution, is generally around f/4. Therefore it's hardly possible to improve the performance by stopping down when using (such) slow speed lenses. Remember that f/8 on a four-thirds camera is comparable to f/16 on a full format camera.

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 the image borders) are comparatively pronounced but then this is rather typical for tele zoom "kit" lenses. The problem can be visible at the extreme ends of the range with a peak width of around 1.5px @ 40mm and 1px @ 150mm at the image borders.




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