Olympus M.Zuiko 17mm f/2.8 Pancake - Review / Test Report - Analysis
Lens Reviews - (Micro-)Four-Thirds

Distortion

The M.Zuiko lens produces only a slight degree of barrel distortion (~0.8%) which is only rarely noticeable in field conditions. However, this is only a part of the truth. Micro-4/3 images are auto-corrected according to the stored lens profile (lens firmware) - this is done either by the camera directly (JPEG) or by the more popular RAW-converters a la Photoshop. The "untouched RAW" results (thus the principal capability of the lens) are much worse with a barrel distortion as bad as ~4.5% which is extreme (poor) for a prime lens.

Move your mouse cursor across the image to switch between the two variants (corrected/uncorrected RAW file).

Vignetting

Vignetting is not auto-corrected but it's quite well controlled anyway. At f/2.8 the problem can be noticed in some field conditions but it's nothing extreme either at ~0.8EV. The vignetting isn't really field-relevant anymore from f/4 onwards.

MTF (resolution)

The Olympus lens disappoints somewhat regarding its resolution capabilities. There's nothing wrong whatsoever with the center quality which is generally on an excellent level throughout the tested aperture range. However, the border quality is only good (till f/8). The extreme corners are very soft at f/2.8 and they do barely reach good levels around f/5.6.

The M.Zuiko seems to maintain a quite punchy contrast at close focus distances (unlike the Panasonic 20mm f/1.7).

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 are usually easy to correct during post-processing but for whatever reason this aspect is not auto-corrected. This is insofar surprising because the M.Zuiko has quite a problem here with an average CA pixel width of up to 3px at the borders. Let's hope that this issue will be corrected via a firmware update soon because this is disturbing indeed.

Here's a sample crop illustrating the problem:




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