To measure lens vignetting and light fall-off we photographed a white
target with a highly diffused custom filter. The lenses were tested at their
widest focal lengths with the aperture wide open
in Aperture Priority mode. The images were analysed with Imatest and the
full areas presented here at a reduced resolution. Bigger percentages are
better.
Most wide angle lenses suffer from significant light fall-off, but the Olympus 7-14mm performs remarkably well in this regard especially considering its extreme coverage, losing just one quarter of its light in the far corners. Try comparing it with Canon's 17-85mm EF-S which at 17mm on a cropped body
falls off to 57.8%, or to almost half the brightness at the corners; see here.
Lenses for full-frame bodies perform even worse in this regard - compare
the Canon 24-105mm and 17-40mm lenses on the Canon EOS 5D which at wide angle and f4 see the
light fall off by almost two thirds in the corners; see here.
Note: the off-center nature of the 7-14mm result is due to the difficulty
capturing our target at such a wide angle.
To measure lens vignetting and light fall-off we photographed a white
target with a highly diffused custom filter. The lenses were tested at their
longest focal lengths with the aperture wide open
in Aperture Priority mode. The images were analysed with Imatest and the
full areas presented here at a reduced resolution. Bigger percentages are
better.
Once again, the 7-14mm loses just 25% of its light in the corners - a very respectable result and one which confirms one of the claimed advantages of the Four Thirds system.
