I have had the GH6 now for a bit more than one Month and it is time to get to conclusions in terms of the image quality in both photo and video.
In order to do that I have ran the GH6 side by side with the GH5M2 so far in my opinion the best hybrid Micro Four Thirds camera.
There have been a number of reviews online with regards to the GH6 video mode and for me two have stood out.
The first is the review from CineD and the second is from CVP
You do need to take into account a combination of factors when you look at video because the functionality and the camera image pipeline are what makes the video.
In general terms when it comes to functionality and codecs offered the GH6 is simply incredible. I have taken the opportunity to start bird video project and that would have not been possible with the GH5M2 or any previous GH series camera.
You can follow my work as it develops here
For the first time I am shooting in VLOG an entire project and this is due to the implementation in the GH6.
In the GH6 the implementation of VLOG is similar to what is done in the GH5s and the S series. So when you shoot in VLOG the camera is applying a negative adjustment of 1 1/3 stops behind the scenes.
This means when you are shooting at the 250 base ISO the camera is actually internally working at ISO 100.
In addition the GH6 no longer underexposed middle grey behind the scenes and it is spot on the grey card and in the RAW linear data.
In addition we now have a Dynamic Range Boost functionality that blends two frames one at High Gain and one at Low Gain to give you additional headroom in the highlights.
The result is that when you look at VLOG you have increased performance with dynamic range boost on from ISO 2000 and very strong dynamic range up to ISO 6400.
I have run some read noise tests using my astrophotography software and then applying the exposure shifts I come with the above result. Take into account that dynamic range in the GH5M2 is clipped on the highlights at 1 stop less so in reality although the graph seems to indicate that the GH5M2 at ISO 400 has more dynamic range this is not actually the case. However that is true is that up to ISO 1600 when the GH6 has dynamic range boost OFF the GH5M2 outperforms the GH6 in video.
I have shot side by side video and I will post on my YouTube channel some time soon.
However the first conclusion is:
if you do not need 4k120fps or 5.7k and don’t exceed ISO 1600 the GH5M2 is a better choice
What does this actually mean and how low light can you go? In practical terms f/2 1/60 ISO 1600 means 17 lux middle grey typical of floodlight buildings exteriors so not that dark but not that bright either. An indoor lounge with decent lights will have this level of illumination. Of course you can put a strong ND filter on the GH6 and enjoy more dynamic range however this has a number of other side effects.
The second conclusion is
Using dynamic range boost gives you 1 1/3 stops improvement on the GH5M2 from ISO 2000 and more highlight headroom but worse noise performance at low ISO
So what is the use case that will definitely favour the GH6? Typically need for high quality high frame rate formats and decent low light performance. The camera does pretty well up to ISO 6400 in VLOG.
If you don’t use VLOG there is noise reduction in camera so although it looks clean the details is not anymore there. So personally I would use VLOG when possible with the GH6.
When it comes to photos the design choices of the GH6 backfire. The camera has incredibly high levels of read noise as per this graphic.
In addition the read noise is higher in the low ISO before it turns to ISO 800 when dual gain output is in action.
This has of course a direct impact on the theoretical maximum dynamic range.
Here you can see that at values up to ISO 640 the GH5M2 really has an edge and the improvement of the GH6 is really limited to the region between 800 and 3200 the benefit is modest at best 0.5 stops.
So the third conclusion is:
If you are interested in the best photographic dynamic range in micro four thirds the GH5M2 (and the G9) are better choices
As an example those two images shot outdoor show that in effect our eyes do not really see read noise in a bright scene and once scaled the two camera cannot be taken apart. However if you had shot a long exposure at low ISO you will see grain with the GH6 under ISO 800.
For how hard I try I could not tell the difference between the two images above once processed and scaled.
Final disclosure all my figures look at pixel level noise and dynamic range. Scaling to a common size as shown by the image above will benefit the GH6 more as it has higher resolution but the difference is no so large that the data above is not valid so in general all I said above holds.
I have provided test files to Bill Claff of PhotonstoPhotos and he will publish more reliable and scientific results in due course.
We are both puzzled by the GH6 design and are waiting for another raw converter support to reconfirm however the triangulation of my data with other sources holds so I am quite confident of what I wrote here.