Since last year I was a big believer of the 14-42mm MK2 lens, its super sharp, has nice contrast and works great with wet lenses like the Nauticam WWL-1 to provide a really versatile underwater combo.
Previously I had the 'power zoom' variant - but from the reviews the MK2 was a better lens - so I got a copy of that and have been using it ever since, however at the weekend I noticed something in my footage and compared the two lenses, which has made me consider this over the MK2.
If using Shutter Priority mode (so keeping at 1/60 for 30fps) on my GH4 and keeping the ISO at 400 - I would let the camera ride the IRIS to control exposure, however while reviewing the footage in FCPX, I could see in both the footage and the waveforms clear 'steps' when the camera adjusts the aperture to keep the exposure correctly.
Having a play at on land with the PZ lens - it definitely doesn't do this and although does move from f4 to say f7 - it does it in a smooth fashion with no detectable steps or jumps in exposure.
Just thought I would post, this if anyone is looking at either of the 14-42mm for video use.