Olympus M.Zuiko Digital 12-50 mm f/3.5-6.3 ED EZ
- quite solid and sealed casing,
- useful focal length range,
- good image quality in the frame centre,
- sensibly corrected chromatic aberration,
- slight coma,
- low astigmatism,
- negligible vignetting at longer focal lengths,
- fast and efficient autofocus.
- average image quality on the edge of the frame,
- very high distortion on the wide angle,
- significant vignetting at the shortest focal length,
- weak work against bright light.
I like writing the summaries of Olympus optics because usually I can praise the tested lenses. Olympus has always produced good lenses. Unfortunately the summary of the Olympus M.Zuiko Digital 12–50 mm f/3.5–6.3 ED EZ will be an exception because it won’t feature a lot of praise. I got an impression that the constructors of this device focused on providing a useful range of focal lengths closed in a small casing, weather sealed and featuring an electronic MSC (Movie & Still Compatible) mechanism. They forgot, however, about such important things as good optics and a decent aperture fastness (not even mentioning good). In fact that slow aperture is the main reason of the bitter overtone of this summary. I keep repeating it ad nauseam that the small sensor of the Micro 4/3 system makes it possible to construct small but fast lenses. Here we get one of the slowest universal zoom lenses available on the market. You would look in vain for such slow “zooms” with a similar range of angles of view in the systems with bigger sensors. An f/6.3 aperture at the longer end you can met only in some 18-2xx mm class lenses for APS-C sensors. Even 14-1xx mm megazooms designed for the Micro 4/3 system are faster at their longer end. A slow aperture and densely packed Micro 4/3 sensors entail one more unpleasant consequence - a strong influence of diffraction. That diffraction, supported by other optical aberrations which, near the maximum relative aperture (often used in such slow constructions as this one) are simply inevitable, makes the lens’s resolution performance rather average. When a lens is weak in such important categories as aperture and resolution and has a slip-up in the form of a bad performance against bright light, its other advantages become somehow less noticeable.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -