Lens review

Olympus M.Zuiko Digital 12-50 mm f/3.5-6.3 ED EZ

6. Distortion

The idea behind the Micro Four Thirds system is such that the distortion doesn’t have to be corrected by optics because the software can do that job. It entails constructing lenses with wider fields of view because the images after the distortion correction are cropped. In order to keep the angle of view as stated in the specifications the original field must be a bit bigger.

Such a solution has its advantages. When you give up correcting one optical aberration you can correct the others far more efficiently. How does the Olympus 12-50 mm fare? Let’s deal with JPEG files first.

At the widest angle even the software didn’t manage to correct the distortion completely. At 12 mm focal length you get noticeable barrel distortion which value we described as –2.25%. When you progress to longer focal lengths the problems disappear. Both in the middle of the focal length range and on its longer end the distortion is by and large zero. Officially the values are 0.02% and 0.11% respectively but, within the margin of error, they are zero.

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Raw files are quite another matter. At the widest angle of view we deal with huge barrel amounting to –6.87%. Of course it decreased with the raise of focal length because at 19 mm it is –1.2%. It becomes zero near 26 mm (the official result there being –0.10%) and turns into a slight “pincushion” at longer focal lengths. At the maximum focal length the result gets to 0.97%.

Olympus E-PL1, 12 mm, JPEG

Olympus E-PL1, 26 mm, JPEG

Olympus E-PL1, 50 mm, JPEG

Olympus E-PL1, 12 mm, RAW

Olympus E-PL1, 26 mm, RAW

Olympus E-PL1, 50 mm, RAW