After a few months of using the GH6 is time to answer the question pretty much every GH5 user is asking now.
The answer as always is … it depends. I hope this article will help you clarify your thinking.
I have done a number of tests on all the GH5 and GH6 series cameras including the original GH5, the GH5S, the GH5M2 and the GH6.
While many people talk about dynamic range most only care about noise and in particular if this will show in your footage or not.
Unfortunately read noise accurate calculation are only possible for RAW image files not video. Video has an additional issue which is temporal noise.
As noise is random by nature each frame will have its own noise and the changes in noise generate that flickering effect that everybody hates. This is called temporal noise and to an extent every camera has it.
Obviously if you have less noise you will see less flickering but all cameras will have some.
The other discussion that has been going on forever is that large pixels are better for low noise, this is also not true as more pixels can be added and noise averaged out. So the only thing that matters is sensor size, sensor construction and the sensor coating.
The original GH5 did not have a great coating so when the GH5M2 was released sharing the same coating of the G9 most people were saying well it won’t matter much while instead it does.
The benefit that the AR coating brings to the GH5M2 compared to the original GH5 is around 2/3 Stops which is not negligible.
The other difference among the various GH cameras is how VLOG is implemented.
In the GH5/GH5M2 VLOG is simply a curve and achieves no major benefit compared to other photo styles but it avoids you clipping highlights at expense of additional noise. This noise is managed overexposing 1 stop.
In the GH5s/GH6 VLOG applies underexposure behind the scenes of 1 and 1 1/3 stops so dynamic range is maximized. Both cameras have strategy to deal with noise. The GH5S applies noise filtering the GH6 scaling the net result is that VLOG in those camera is better than shooting something else.
Using a mix of read noise on RAW files and calculation of how noise is managed I have created the following chart that shows how noise goes at bit level when ISO goes up.
Here you can see all the cameras I think this graphic explains pretty much what happens at high ISO. For low ISO you need to take into account shot noise and my analysis is not able to evaluate that however this will make a small difference to the evaluations.
So lets go into the specifics
I am a hybrid user I want the best of both worlds which camera is better for me?
The GH5M2 is currently the best camera in this category, it offers the best still image performance, it has IBIS and video is very good and can be improved with an external recorder if you wish. It also records 8 bits which is fine for those who do not want 10 bits at all costs and uses SD cards. The dynamic range of a still image is the best of all GH series cameras as seen on photonstophotos. Remember that RAW files are not denoised or scaled like video.
I am a GH5 video user should I buy a GH6
Assuming that you shoot vlog because if you don’t any camera works just fine the answer is yes unless you are always at ISO 400 with your GH5 and do not want to buy more ND filter the GH6 is a significant step forward.
You need to evaluate however if you need all the GH6 offers.
I am a GH5S video user is the GH6 for me?
While the GH6 performance is better than the GH5S in the high ISO zone at low ISO is worse. The GH6 has IBIS and all the features the GH5S has however it is limited to 12800. The GH6 also produces 25 megapixels photos but as a GH5S user this was probably not important.
So the answer is yes if you don’t need really high ISO (>12800).
I am a GH5M2 video user is the GH6 for me?
If you don’t mind ND filters, use the camera in both daylight and low light and you need any of the features like 120fps 4k then the answer is yes.
The GH5 has been a very competitive camera and the GH5M2 further improved on it. The GH5S has its own niche and all of those are strong proposition. When looking at the GH6 the key criteria is that you are focused on video and that you need all the codecs and feature the camera has.
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.
In 2018 I wrote the original article as I had acquired the GH5 and I was faced with a ton of non-sense on which format to use when I was shooting video. With the S series software stack Panasonic has made some changes to the options available and I thought it was about time to refresh the original article. As Before I will focus my analysis on 4K video and ignore other formats. This time I will be looking at the NTSC standard of 29.97 and 59.94 frames per second. This is simply because today majority of content produced by Panasonic consumer digital cameras is consumed online and all computer screen work at 60 Hz refresh rate so shooting anything different than 30 or 60 will result in choppy video. This presents some challenges if you are in a PAL zone and are shooting under artificial lights however for the purpose of this article I want to just ignore this issue, obviously you could shoot 24 fps and hope in a 24 – 30 conversion which is scatty of course. For simplicity I will refer to 30 and 60 fps and not exact values.
Today we have 5 settings for UHD
200 Mbps 420 10 Bits Long GOP 60 fps
150 Mbps 420 8 Bits Long GOP 60 fps
100 Mbps 420 8 Bits Long GOP 30 fps
150 Mbps 422 10 Bits Long GOP 30 fps
400 Mbps 422 10 Bits All-Intra 30 fps.
The last option is only available on the GH5 series and on the S1H. The first option is only available on the S series and the GH5M2.
Long GOP vs All Intra
The difference between Long GOP and All Intra is that in the Long GOP what is encoded is a group of pictures (GOP) and not separate individual pictures.
Within a Group of Pictures there are different type of frames:
I (Intra coded) frames containing a full picture
P (Predictive coded) frames containing motion interpolated picture based on a prediction from previous frames
B (bi-predictive coded) frames containing a prediction from previous or future frames
It is important to note that frames are not stored sequentially in a GOP and therefore the GOP needs to be decoded and the frames reordered to be played, this requires processing power.
The reason why H264/HEVC is very efficient is that within a group of picture there is only one full frame and the rest are predictions clearly if the prediction algorithm is accurate the level of perceived quality of long GOP is very high and similar to All-Intra clips.
This is the reason why comparing All Intra and Long Gop using static scenes or scenes with repetitive movement that can be predicted very accurately by the codec is a fundamental error.
So which format should you choose?
In order to understand the workings we need to dig deeper into the structure of the GOP but before doing so let’s evaluate the All-Intra codec.
AVC All-Intra explanation
This codec records at 400 Mbps so with 30 fps this means circa 13.4 Mbits per frame or 1.67 MB per frame and there is no motion interpolation so each frame is independent from the others. The implementation of All-Intra of the GH5 does not make use of CABAC entropy but only CAVLC coding is used, this makes the resulting files easier to read and to edit. The idea of All intra is that you don’t require powerful hardware to edit without conversion in an intermediate codec. However based on my experience this is not entirely through and you need a decent GPU to play it back and edit real time without issues.
If you consider a Jpeg image of your 3840×2160 frame on the GH5 you see that it stores around 4.8 MB per image because there is no chroma sub-sampling so if you wanted to have exactly the same result you would need to use ProRes 4444 to get a comparable quality (this not even taking into account that Jpeg are 8 bits images).
Video uses chroma sub-sampling so only part of the frame contain colours at a given time. Apple in their ProRes white paper declare that both ProRes 422 and 422 HQ are adequate to process 10 bit colour depth and 422 sub-sampling however they show some quality differences and different headroom for editing. If you count 50% for 4.2:0 sub-sampling and 67% for 422 you get around 2.34 MB and 3.5 MB frame sizes that correspond to ProRes 422 and ProRes 422 HQ individual frame sizes.
it would appear that All Intra 400 Mbps would fall short of Apple recommended bit-rate for 422 10 bit colour however practical tests show that AVC All intra at 400 Mbps is perceptually identical to ProRes 422 HQ and uses much less space. We also did some SNR measures time ago with the friend Paal Rasmussen and we did not find significant improvements shooting ProRes 422 HQ vs All-I on card.
Long GOP Codecs
Coming back to the other recording quality option we still need to evaluate how the various long GOP codecs compare relative to each other.
In order to fully understand a codec we need to decompose the GOP into the individual frames and evaluate the information recorded. If you look on Wikipedia it will tell you that P frames are approximately half the size of an I frame and B frame are 25%. I have analysed the Panasonic GH5M2 clips using ffprobe a component of ffmpeg that tells you what is exactly in each frame to see if this explains some of the people claims that there is no difference between the settings.
Link to Panasonic on the H264 implementation is here: documentation
There is unfortunately no documentation of the HEVC implementation that I have found to date.
200 Mbps 420 10 Bits Long GOP 60 fps Analysis
An analysis with ffprobe shows a GOP structure with N=30 and M=1 where N is the length in frames of the group of pictures and M is the distance between I or P frames.
This codec does not have B frames but only P frames.
Analysing a set of I frames of a fixed subject at 60 fps resulted in a frame size of 1.16MB for the I frames. This value is quite low however we need to understand that HEVC is much more efficient than H264.
I shot this test video time ago comparing the recording of this codec with a Ninja V in ProRes 422 HQ. As you can see no major differences however I have not pushed the grading in the clip.
The speed ramps in this video use this codec
150 Mbps 420 8 Bits Long GOP 60p Analysis
An analysis with ffprobe shows a GOP structure with N=30 and M=3 where N is the length in frames of the group of pictures and M is the distance between I or P frames.
So each Group of Pictures is made like this
IBBPBBPBBPBBPBBPBBPBBPBBPBBPBB before it repeats again.
Analysing a set of I frames of a fixed subject at 30 fps resulted in a frame size of 1.26MB for the I frames.
One very important aspect of the 150 Mbps codec is that as the GOP is double the length of the single frame rate 100 Mbps codec there are the same number of key frames per second and therefore it is NOT true that this codec is better at predicting motion however the additional frames result in better slow motion performance than what is done in software in majority of cases.
100 Mbps 420 8 Bits Long Gop 30 fps Analysis
An analysis with ffprobe shows a GOP structure with N=15 and M=3 where N is the length in frames of the group of pictures and M is the distance between I or P frames.
So each Group of Picture is made like this
IBBPBBPBBPBBPBBP before it repeats again.
Analysing a set of I frames of a fixed subject at 30 fps resulted in a frame size of 1.49MB for the I frames which is the highest if we exclude All I.
150Mbps 422 10 Bits Long Gop 30 fps
An analysis with ffprobe shows a GOP structure with N=15 and M=1 which means this codec does not use B frames but just I and P frames so the GOP structure is as follows:
IPPPPPPPPPPPPPP before it repeats again.
Analysing a set of I frames of a fixed subject at 30 fps resulted in a frame size of 1.25MB for the I frames.
H264 Codec Ranking for Static Image Quality UHD
So in terms of absolute image quality and not taking into account other factors the Panasonic GH5M2 and S series Movie recording settings ranked by codec quality are as follows:
400 Mbps 422 10 Bit All intra 30 fps (1.67 MB per frame)
100 Mbps 420 8 Bit Long Gop 30 fps (1.49 MB per frame)
150 Mbps 420 8 Bit Long Gop 60 fps (1.26 MB per frame)
150 Mbps 422 10 Bit Long Gop 30 fps (1.25 MB per frame)
The 100 Mbps and 400 Mbps codec are marginally different with the 150 Mbps long GOP really far away.
Note that as the technology is different I cannot directly compare the new 200 Mbps codec however based on visual impression and ability to grade I would recommend this over the 150 Mbps 420 8 bits
If you have a camera that has the 400 Mbps All Intra this remains the best format to use. V90 cards have dropped in price and are now available up to 256 GB. Unfortunately this option is only available on the GH5 series and on the S1H.
If you have a camera that does not have the All-I you can of course purchase an external recorder that in some cases will allow you to shoot RAW however this is not necessarily going to give better image quality and will definitely extend your processing time.
My revised advice, if your camera does not have the ALL I and you don’t have an external recorded, is as follows:
Use the 100 Mbps Long Gop codec it is very efficient in the compression and the perceived quality is very good. You need to get the exposure and white balance right in camera as the clips may not withstand extensive corrections. There is a risk with footage with a lot of motion of some errors in motion interpolation that can generate artefacts but this based on experience is not very high.
Use the new 200 Mbps HEVC for double frame rate it is not hard to process as HEVC 10 bits has hardware acceleration on all platforms.
Generally there appears to be no benefit using the internal 422 10 Bit codec nor the 420 8 bit double frame rate due to the limitations of the GOP structure, in addition the lack of hardware acceleration for H264 10 bits means you will need to convert the files for editing and they do not open with standard programs or load on phones or tablets. The same is true for All Intra but at least you can edit it ok.
To conclude this is a summary table with all key information
A certain number of GH5 users have upgraded to the S5, I was one of them until I sold the camera after 1 month of using and after buying a Ninja V. If you are a Panasonic S1/S5 user you need not only to contend with recording time limits but also with lack of codecs on the camera to fully use the potential that it has. You need to add an external recorder to really see the benefits because in real life situations you are not shooting a step chart so the dynamic range is destroyed by compression quality and errors and SNR drops. It would be interesting to test how does the GH5M2 400 Mbps compare with one of the S cameras using the 150 Mbps 10 bit codec but this is not something I did. I would only warn everyone going down that path that you may get less than what you think and you may require additional hardware to get there. Take also into account that S series only shoot 50/60 fps in APSC/Super35 mode and that in full frame mode there is a substantial amount of rolling shutter that makes pans and tilt practically not possible.