But what about comparing the GH3 with the predecessor GH2. Both cameras feature the ETC mode. To test this, I set up both cameras to video record the same scene, and used the Lumix G 100-300mm f/4-5.6 lens at 100mm f/5.6. I already know that this lens is very sharp at 100mm, especially when stopped down to f/5.6.
Here is a comparison of the videos outputs:
Also, here are some 100% crops from the video streams:
I think that the cameras perform quite similarly, in this case. I'm actually thinking that the GH2 videos look better in terms of sharpness and noise at ISO 3200. The GH3 has better colours, though.
Of course, the GH3 goes all the way up to ISO 6400 for video, also for ETC, which is an advantage over the GH2 anyway.
One can also argue whether ISO 200 is the same with both cameras. Do the cameras have the same sensitivity at ISO 200, and at higher ISOs? I don't think the jury is fully out on this yet. To try to assess this, I tried to take images at ISO 200 with the cameras GH1, GH2 and GH3. However, even after seeing the results, I am not sure how to interpret them.
The ETC mode is very useful, but avoid using it at high ISO, where it adds quite a bit of noise. The GH2 and GH3 appear to be quite similar in this respect.
Using the Lumix G 100-300mm f/4-5.6 at 300mm in combination with the ETC mode gives an effective reach of around 1500mm equivalent, filling the moon into almost the entire video frame: