From the link that Ranger 9 posted (very interesting reading*, thanks) this appears to be the issue. The 4/3 lenses are designed for the sensor.
What interests me at this point is investigation into which adapted lenses exhibit this, and is it strictly related to focal length or to other factors specific to individual lenses. I suppose it is possible (probable?) that some lenses are naturally telecentric and therefore should work fine on the G1.
*They need a proofreader: "To maximize the performance of the image sensor, the camera must be designed so that the light is straight even on the periphery of even on the periphery of the image sensor surface."
What interests me at this point is investigation into which adapted lenses exhibit this, and is it strictly related to focal length or to other factors specific to individual lenses. I suppose it is possible (probable?) that some lenses are naturally telecentric and therefore should work fine on the G1.
*They need a proofreader: "To maximize the performance of the image sensor, the camera must be designed so that the light is straight even on the periphery of even on the periphery of the image sensor surface."