 The mass of the R9 was reduced by 100g (to 790g) from the R8, achieved by switching to a magnesium casting for the top plate (formerly zinc alloy) and substituting aluminum for steel at the bottom plate's frame.Electronic changes included the ability to tune the sensitivity of matrix metering in steps of 0.1 EV independently of the other metering modes, and several improvements to the flash support.Metz's HSS (High Speed Sync) flash mode was now supported, allowing fill flash at shutter speeds greater than the X-sync speed by the use of many repeated small flashes of the electronic flashgun.