I hope you found the tests useful and I guess the key question is:
Is the GH5S still worth it in 2022?
I have prepared a comparison table with the GH5 and GH5M2 using data available and for noise my subjective measurements supported by the video evidence.
As you can see from the table the GH5S still has some unique features:
RAW support (ProRes RAW and BRAW)
High ISO performance straight out of camera
Slightly lighter and better battery life
So if any of the above are essential to you there is still a case for the GH5S.
However the GH5M2 with Neat Video will cost you $1,699+$129=$1,828, for sure you will have to work without Vlog and RAW but you will have many other benefits and you will not need a recorder to shoot 50/60 fps bringing the overall cost down significantly.
For part 3 of my test I ran the GH5S side by side with GH5M2 with the same settings used for daylight. The GH5S used VLOG which is the best photo style for it while the GH5M2 used CineD2, again the best photo style for it. Bear in mind if you had run this comparison with both cameras on VLOG the GH5S would have trashed the GH5M2 at high ISO because the implementation of VLOG in the GH5M2 is simply not performing.
The two cameras were set in multi metering with focus at hyperfocal distance. I tried to match the field of view using the 10-25mm on the GH5M2, make no mistake the PL 15/1.7 I used on the GH5S is an amazing and very sharp lens. Both cameras were set to auto white balance and I put the GH5M2 in auto ISO because it shows on screen the value it is using while the GH5S was set in complete manual. Whenever the GH5S was displaying a negative value on the meter I would increase ISO 1/3 Ev. The GH5M2 was left to deal with it in auto as I had previously confirmed the meters were aligned, or at least this is what I thought until this test.
I started all the way from ISO 200 and waited until night fall.
If you want to watch the video and form your own view here is the link. You will need a Tv with zoom function to be able to see the fine details.
My expectation was that the cameras would perform almost the same until ISO 1600 at that point the dual gain of the GH5S should produce better results. I will spare the analysis at lower ISO values as it does not really say much.
As explained in the video you need to focus on three part of the image. The top part and any residual tone of the sky tells you if the camera is loosing DR. The tables at the bottom are a sign of loss of detail due to noise but also of possible temporal noise reduction. Temporal noise is a flickering resulting from noise scattered differently in the frames. When the image retains detail but has this flicker it is said to have temporal noise. If the clip looks stable but lacking a bit of edge details it is a sign of potential temporal noise reduction in camera.
Due to the lower pixel count temporal noise reduction in the GH5S would perform better than in a higher pixel count camera.
Here the GH5S is in low gain and my expectation was performance to be very similar. At this ISO value the GH5S retained good detail however showed more noise in each part of the frame.
The noise levels appear identical in the static parts of the frame.
All in all at ISO 1250 the situation appears very similar the GH5S has a bit more noise but still have detail compared to the GH5M2.
The light dropped suddenly so I did not manage to record the ISO 1600 step on both camera at the same time as I was distracted by external factors (had to order at the bar).
Although the noise appear similar I would say the GH5S retained more detail at ISO 2000, consider the observation is far away and on the edges of the frame so it is a difficult scenario.
Looking at the static part gives a different picture with the GH5M2 having an edge and the GH5S smudging details.
I was expecting the GH5S to be a clear winner at its second native ISO.
The part of the frame with motion did not show a much better detail for the GH5S while the static part looked cleaner.
This behaviour makes me think that the GH5S has a stronger temporal noise reduction filter. When it does not detect motion it goes down hard resulting in a very clean image. When it does detect movement it becomes more cautious especially if the moving parts use only a small area. This would explain the mixed behaviour in the ISO 2500 situation.
Overall I was expecting much better performance and a clear difference between the two.
My expectation was that as the ISO was going up the gap between the two cameras would have increased however at ISO 3200 I was surprised to see the GH5M2 made a recovery and the quality is almost identical.
In addition I can see the GH5S noise reduction starting to eliminate some details when it can’t quite work out what to do. Look at the table tops near the two walkers in the frame.
At this point I was presented an additional surprise the two camera started to have a gap in the metering so for a good few minutes the GH5M2 stayed on ISO 3200 while the GH5S was reaching out for more gain.
Ultimately this resulted in identical image quality in the parts with motion with the GH5S retaining some fine details better but the GH5M2 producing at the end a comparable result.
I won’t bore you with the static parts as they look identical.
The GH5M2 reached ISO 4000 however the GH5S had already moved to 5000. The consequence is that the image quality was the same.
Again the static parts were the same.
Eventually both cameras were at ISO 5000 and here I could see a lead of the GH5S in the motion details but no benefit in the static details in terms of sharpness. However when you actually play the footage you can see the flickering of the temporal noise on the GH5M2.
The static details retain the same definition and resolution.
At this point is very clear to me that what is giving an edge up to now to the GH5S is the superior performance of noise reduction in camera as the actual dynamic range did not seem to be an element. If at all the sky becomes washed out sooner in the GH5S.
From this point onwards the GH5S takes the lead however I would not say that the resulting image quality was very high. I would frankly avoid this ISO level but in desperate cases can certainly be used.
Perhaps more interestingly the GH5M2 although more noisy seems to preserver more details of the static part.
It became apparent during this test and you will see it clearly in the video that the GH5S has a very effective in camera noise reduction (even with NR=-5 this is still on) potentially because it does not have many pixels and can be quite aggressive with it. I tried using Neat Video with the GH5S however there was loss of detail, with the GH5M2 I could apply a temporal filter to the ISO 5000 you can see the results in the video and see what you think.
I was surprised to see the camera meter reading differently considering the matched set up. I also could see that the light level had to fall considerably so that the GH5S would have a benefit. In substance until both cameras were at ISO 5000 (I was using f/1.7 lenses) it did not look like the higher sensitivity of the GH5S was sufficient on its own to give a performance edge.
I continued the test all the way to ISO 25600 for the GH5S the results were not exciting although you could say the camera does a decent job at showing some information. In general it seemed the camera was running out of dynamic range and also of image quality.
At this point (ISO 12800) I would say that the benefit of the GH5S was now a full stop. In addition it can go to 25600.
Low Light Sensitivity
I was expecting to see a material difference between the GH5S and the GH5M2 from ISO 1600 or at latest ISO 2500 with this gap growing at higher values. What I have seen instead is a bizarre progression where the GH5M2 would catch up and almost match the GH5S until ISO 4000 with a clear benefit only when the exposure was 5000 for both. It looks like in line with the aptina Dr Pix paper benefits only arrive near 0.01 lux*sec becoming higher later.
So we need 50% of ambient light * exposure time / aperture stop to be 0.01.
If we think about it f/2 1/60 this means aperture in stop is 2 which means a factor of 4. So working the inverse in order to get 0.01 lux*sec we would have 2*60*4*0.01=4.8 Lux.
If we consider an f/1/7 lens than this becomes 3.4 Lux and finally with an f/1.4 lens this would be 2.4 Lux.
In reality most f/1.4 or f/1.7 lenses really are just f/1.8 or f/2 so a value of 4 Lux for ambient light is reasonable. And this is the point where the benefit would start getting better as it goes darker. This is also consistent with my test the real performance difference started really to manifest a lot at ISO 5000 and became higher later.
We also have to consider thought that certain part of the image like the deep shadows will show a benefit sooner even if the ambient light is broadly sufficient. So it is not as clear cut as it would appear and the test confirmed such behaviours.
Perhaps the biggest surprise was how effective a traditional front illuminated sensor can be and how small was the gap with the GH5M2.
A key difference between my tests and others you can find on the net is that nobody actually runs tests with two cameras side by side and we have seen that at high ISO values the cameras did not meter exactly the same but what matters is the image quality at that point in time so the test still stands.
One thing has to be said though and this is that as of today if you want a micro four thirds camera style device (not a box or a cinema camera with no weather sealing) that works in low light with VLOG you are left with only one choice and that is the GH5S.
In the next part a wrap and some considerations about use cases and current competition for the GH5S.
The second part of the test consisted in running the GH5S in parallel to the GH5M2 using CineD2. If you wonder why I did not use VLOG on the GH5M2 is because as discussed in a previous article VLOG on the GH5/GH5M2 is just a picture profile and does not really do anything other than deteriorate the noise in the shadows. So I used CineD2 as I wanted the maximum performance out of the GH5M2. The GH5S instead performs better in VLOG for reasons explained in the VLOG article as well.
So with the two cameras on tripods I went out for a walk and took several shots with similar exposure settings. Instead of using ISO 400 I used 200 on the GH5M2 which means the lens was one stop brighter on the GH5M2.
The practical tests confirmed what I was expecting based on the light box tests:
The GH5S has a tendency to oversaturated reds and move blue to cyan so deep blues in the sky are almost never available. This was not so much of an issue during this test as the sky was overcast however you can see the clouds do not really have any blue tones.
Auto white balance during the day performed consistently to the GH5M2 generating most times the same reading or at most a 200K difference. On this basis I do not understand why users speak about a magenta cast in some shots.
The GH5S had better battery performance of the GH5M2 and I think this has to do with the LCD which is now much dimmer than the new camera as you can see in the picture.
I did not see any more dynamic range in the GH5S. I would say a tad less than the GH5M2 on CineD2 at base ISO. This is visible in the second scene where I spot metered on the subject. Both camera had almost no tones left in the sky although they did not clip with the GH5M2 having perhaps an edge there.
Looking at the waveform after ETTR with the cameras showing near clipping you can see that the highlights are practically the same however VLOG has lower midtones and less darks.
This is the full video on youtube so you can make your own calls. The footage has been stretched to maximise DR ad hoc in the first scene and hues have been corrected for daylight. No other grading has been performed. In the second scene both cameras were maxed out and no further stretching has been done as it was not improving the scene.
The potential benefit of the GH5S over other models
The following table extrapolates the GH5S dynamic range considering a shift of 3dB in gain (ISO 400 -> 200 shifted)
Delta GH5M2 Max
Delta GH5 Max
PDR table with gain shit
Please note this is an extrapolation I have not take measures however assuming VLOG impacts all cameras equally once gain is taken into account what you see there is that the GH5S has a potential benefit between 0.76 and 1.46 Ev over the original GH5 which is consistent with user experiences and website tests.
When you look at the GH5M2 the potential benefit drops to 0.5 and under 1600 is almost zero becoming 2/3 Ev when the GH5S is in high gain. This is also consistent to various tests on websites like dpreview and CineD.
The table does not consider however that CineD2 on the GH5M2 does accomplish more than VLOG in virtue of less noise and also does not consider the fact that some of the DR will be lost in the underexposure happening behind the scenes.
Part 2 Wrap Up
It is not difficult to see that the GH5S has good performance in daylight conditions however it does not really have any edge worth investing in it for this use case. So if you are not always at high ISO levels (>>1600) you may be getting better value from the GH5M2 that costs less takes photos and has IBIS. To be perfectly honest due to the way VLOG works I did not see major benefit even when I tested the S5 because the extra DR in the highlight was not really useful.
When we look at the GH5 instead the GH5S does remain superior but this is due to weakness of the GH5 itself. It really is quite clear that the software stack of the GH5 is really dated and the camera fairly noisy.
In the next article I will analyse two side by side shots of the GH5S and GH5M2 in low light.
Since its announcement exactly 4 years ago the GH5S has been an enigmatic and successful camera for Panasonic. Today 4 January 2022 it still retails at £1,899 and it has upheld price more than the original GH5.
You would wonder who would want to get a 10 megapixel camera without stabilisation and the answer is many people that are solely focussed on video. The camera has built a reputation for low light performance and dynamic range and has been praised for its ‘color science if there is such a thing.
So after using the GH5M2 for six months I decided to rent a unit from Wex Photo and run a side by side comparison for myself.
When I say side by side I do not mean just in theory I mean in practical with the cameras close to each other and shooting the same scene.
For my tests I used a light box and a set of grey, white and color checkers and the same identical lens Panasonic 30mm macro. And for the outdoor scenes I set the GH5s with a Panasonic Leica 15mm 1.7 and the GH5M2 with a 10-25mm. As the GH5S has a multi-aspect sensor I needed to zoom the lens to less than 14mm to get the same field of view.
Before getting into the actual tests it is time to debunk a few myths about the GH5s.
Less Pixels = Less Rolling Shutter not more Dynamic Range
Camera readout is limited mostly by the speed of the Analog to Digital conversion. So having less pixels helps readout and reduces rolling shutter. This is the reason why all camcorder and dedicated cinema cameras have the minimum amount of pixels required and nothing extra.
This is true for the GH5S, the reputable website CineD as well as dpreview show a benefit of a couple of milliseconds for the GH5S over other cameras with a 20 megapixels micro four third sensor. This may be important when doing panning shots or using the camera on a dashboard or gimbal.
On the bigger pixels helping dynamic range there are a number of sources that explain why this is not the case but more importantly the the GH5S sensor has actually a quad bayer structure with cells of 4.6 microns made of 4 pixels each. So in reality the GH5S sensor has 43.64 megapixels arranged in 10.91 million cells that give 10.91 megapixels in 4:3 aspect ratio 9.07 megapixels in the 17:9 wide format. So not only bigger pixels are no help to dynamic range but the GH5S sensor actually has more pixels.
The sensor in the GH5S does not have higher dynamic range than other MFT cameras
Photonstophotos managed by Bill Claff is the only site that has measures of almost all camera models. While engineering dynamic range is purely determined by the difference between saturation signal and lowest readable signal, photographic dynamic range is what we see and is generally determined from setting a defined SNR for the image scaled to 12″ size long or 8 megapixels. This is roughly the 4K video resolution so it is a good starting point.
From this graph we can see that the G9, although based on the same sensor of the original GH5, outperforms the latter and the GH5s when it comes to dynamic range.
I am always cautious with measures taken by others so I did a full test and asked Bill to check the difference.
While in some cases there was an improvement of 0.18 Ev this would not be sufficient to push this sensor above the G9.
So the Panasonic GH5S sensor does NOT have more dynamic range of other Panasonic cameras with more pixels on the same format although it does quite well and at high ISO outperforms the GH5 at RAW level.
The multi aspect sensor has a bigger size in video but this does not improve dynamic range significantly
Due to the multi aspect ratio it is true that the sensor does not loose from a crop when changing aspect however we need to understand more what the potential benefit is.
A higher megapixel sensor with pixel of 3.3 microns will use its whole width and a cropped part of the height. If we look at 5184×2916 pixels surface this measures (5184×3.3)x(2916×3.3)=164.62 square millimeters. The GH5S with a cell size of 4.6 microns will have a surface of (3840×4.6)x(2160×4.6)=175.5 square millimeters.
Considering that dynamic range is proportional to the square root of the surface the improvement would be SQRT(175.5/164.62)=1.032 which in Stops is 0.046. So the larger area does not really do anything in 16:9 aspect ration.
In 17:9 the situation is a bit different and this benefit is 0.14 Ev still nothing so large to have a very significant impact.
During my tests I found the change of horizontal field of view which is what really matters confusing so personally I like to have a standard sensor with crop considering the benefits of multi-aspect are really limited.
The sensor of the GH5S has higher sensitivity
One of the features that the GH5S has is the so called Dual Native ISO. This is a marketing term for the Aptina DR-PIX technology which has been implemented by Sony for some time.
A white paper is here as you can read the technology enables sensors to increase sensitivity at the expense of dynamic range. The potential improvement is up to 5 dB however this is only true for very low light levels. To give an idea at deep twilight there is around 1 lux so with an exposure time of 1/50 of a second we have 0.02 lux*s this is not in the core range for this technology so more is required.
Back illuminated sensor give the additional sensitivity required as explained on Sony semiconductors page.
Now the combination of dual gain and back illumination means that the GH5S can do better at low light levels but also can tolerate very high levels of ISO. So the GH5S has additional high ISO capability for around two stops which means you can almost shoot in the dark. The key question is when does this matter when you have a fast lens.
Looking at an exposure waterfall calculator we can see that with an f/1.4 lens at 1/60 and ISO 3200 we can still cover twilight which is when public illumination is switched on.
In general terms all being equal the GH5S would have around 2/3 stops benefits in low light or in deep shadows compared to other cameras with MFT sensor.
This is quite interesting to test and quite simple using a color checker and a noise reduction software like neat video.
Here the first two samples are grey and black patches in VLOG at ISO 1600 using the Low Gain setting.
We can see that while the noise level on the middle grey is contained the black patch jumps to 4.4.
If we take the same reading manually selecting the High Gain range we can see how the situation changes.
On the middle grey we are in a very similar situation. However when we look now at the black patch we can see that the level of noise has dropped significantly.
So we can see that switching the camera from low to high gain at the same ISO has a significant benefit on darks in terms of noise.
VLOG to the rescue
With what we have said so far there has not been enough to substantiate why the GH5S would have more video dynamic range than the GH5 but VLOG comes to the rescue.
When Panasonic introduced the Varicam 35 in 2014 they were presented with the issue of having too much dynamic range.
Panasonic already have their CineLike Gamma that was able to manage 12 stops of dynamic range however this was no longer sufficient.
So the Varicam35 was provided with RAW output and with AVC Intra recording on their expensive expressp2 cards. VLOG provided an opportunity to compress the camera dynamic range in a 10 bit container that could then be recorded on card.
Panasonic made a first attempt to deliver VLOG to their Lumix with the GH4 however at 8 bit depth it did not work well. The GH5 is the first camera to have a 10 bit implementation however due to the smaller sensor it was limited to a smaller range called VLOG L which covers 12 stops of dynamic range.
A report by EBU indicates that the GH5S has more dynamic range in both CinelikeD and HLG modes compared to VLOG. Those are not scientific but are a suggestion that perhaps for a sensor with a maximum dynamic range around 12 stops VLOG is not the most efficient option. HLG presents challenges due to the color space and gamut differences however CineLike D does not require anything specific to process. Users have complained about the color accuracy of CinelikeD and generally Panasonic has been sponsoring VLOG and so have many websites under the assumption that this was the best way to preserve the full dynamic range.
While this may be true for larger sensors it would appear that this is not definitely true for the smaller MFT format.
In addition the implementation of VLOG among different camera is not the same as I already wrote here.
So in summary it is true that if you want to use VLOG the GH5S is a better option with a benefit that can be around 1 stop at high ISO over the best performing MFT camera at time of writing the GH5M2.
If you want to see the behaviour of the GH5S using a color checker you can appreciate the low level of noise at high ISO.
Color Accuracy and White Balance
I used a vectorscope to evaluate how the GH5S reproduces hues in VLOG. All tests done with factory settings and official Panasonic VLOG
You can see that the skin tone marker is exactly on target however red is more saturated than other colors and cyan is desaturated
The blue use is also shifted towards cyan.
This means that the GH5S can potentially produce a red cast and not give deep blue skies.
The weather was rubbish during my tests however from this example you can see how the red is definitely overboard by looking at the hat of the runner that comes on the scene.
This is something to watch out and a hue correction in post is required in most cases to bring things to normal.
Note that this issue with VLOG and the oversaturated red is also present in the GH5M2 that has very much the same color science or lack of thereof and will produce reddish tones on your skin that need to be corrected.
Take into account that hue correction is not resolved by setting a custom white balance.
For the hardcore pixel peepers I have shot a whole sequence of xrite color checker at all ISO steps
On a positive note the GH5S in VLOG meters correctly unlike the other GH5 siblings that are 1 stop overexposed.
You can see on the waveform monitor that setting the target at zero gives middle grey exactly on 50% on multi metering. On spot it will go at 45% which is what is expected.
Part 1 Wrap Up
From a series of quite simple tests done in a light box my expectation is that the GH5S will do ok but not sensationally in bright scenes and will do better in low light low dynamic range scenes.
In the next article I will analyse two side by side shots of the GH5S and GH5M2 in daylight.
If you have a GH5 (Mark I, II or S) you are probably not just doing underwater video but also taking scenes on land. In fact perhaps you are reading this blog and you do not even use your camera underwater.
Either way you know by now that shooting video just with your camera handheld is not a terribly good idea and the tools required are different from photography where once you have a tripod a remote shutter and a bunch of filters are practically set.
Video requires quite a bit of hardware. I have gone through this process and even tried to adapt some of my underwater hardware but it was really bulky and at the end you are better off with proper gear so I use Smallrig.
Smallrig is a Chinese company that makes tons of various bits for your camera for a variety of situations. The first item you need is a cage and they have just released a new updated version for the GH5 cameras.
Clicking the image above will take you to Amazon UK where you can check details of the item.
The cage is the starting point and you can put your camera strap the weight of 190 grams does not add terribly to the camera and in any case if you have a GH5 you are used to carry some more weight. The cage lives permanently on my GH5 unless I put it in the underwater housing.
I am now going to go through a series of set up that I use with some other components as well but first some words of warning.
Smallrig suggests to use a Nato handle on the left hand side however this blocks the HDMI side port from opening. In addition the arri locating pins are too high and if you use a side handle in arri format it will hang and not be level with the cage.
I wrote Smallrig to tell them and they accepted the feedback the reality is that they do not test designs with camera they run 3D simulations and they do not go and open all the ports, plugs etc. So the only handles that actually work with this cage and do not impede any functionality are in this article.
Monopod/Tripod Rig for Wildlife shooting
The basic rig for monopod and handheld work (this means you hold the camera steady and you do not move) has a top handle and a side handle plus a small microphone and if required an LCD shade.
I have gone through a series of handles for this cage and I have settled for the following items:
We are looking at £180 for all this hardware this stuff is not cheap however I just can’t emphasize how more ergonomic and effective this is compared to holding the camera directly.
I have this rig used it for my deer film project.
There are situations where setting up a gimbal is too much and you want to take simple footage handheld just using the camera IBIS. This works very well with a standard zoom lens like the Panasonic DG Leica 12-60mm or the Lumix 12-60mm.
In those situations is better to have two handles and the set up needs to be as light as possible.
You will notice that the handles are smaller and they are also lighter. If you walk with your camera you are typically using the LCD and with two handles you are able to be much more steady if you were just gripping the camera.
You can also use the EVF instead of the LCD if you prefer to have three points of contact with the camera.
In those situation where you are in a studio or controlled environment you can use manual focus for pulling and usually you also have a monitor to have precise exposure. I tend to use this on a fluid video head and sturdy tripod for indoor shots.
Here I am shooting the mighty PanaLeica 10-25mm and I have my trusted Swit CM-55c field monitor.
I have an atomos ninja however since the GH5M2 has 60 fps in camera at 10 bits I only use it in bright outdoor scenes and the SWIT is just better in terms of tools and lighter.
With the new linear focus option for manual focus you can have a complete 360 degree turn of the wheel for manual focus if you so wish or shorter runs if preferred. I use 300 degrees.
It can be a bit daunting to search for the right items that do the job when you want to use your cage I hope this article will help you making the right choices and save time without having to do the trial error and return process I have done in the last year!
There is no doubt that LOG formats in digital cameras have a halo of mystery around them mostly due to the lack of technical documentation on how they really work. In this short article I will explain how the Panasonic V-Log actually works on different cameras. Some of what you will read may be a surprise to you so I have provided the testing methods and the evidence so you can understand if LOG is something worth considering for you or not. I will aim at making this write up self-contained so you have all the information you need here without having to go and search elsewhere, it is not entirely possible to create a layman version of what is after all a technical subject.
A logarithmic operator is a non-linear function that processes the input signal and maps it to a different output value according to a formula. This is well documented in Panasonic V-Log/V-Gamut technical specifications. If you consider the input reflection (in) you can see how the output is related to the input using two formulas:
IRE = 5.6*in+0.125 (in < cut1 ) *
IRE = c*log10(in+b)+d (in >= cut1 )
Where cut1 = 0.01, b=0.00873, c=0.241514, d=0.598206
There are few implications of this formula that are important:
0 input reflectance is mapped to 7.3% IRE
Dark values are not compressed until IRE=18%
Middle Grey (18% reflectance) is still 42% IRE as standard Rec709
White (90% reflectance) is 61% IRE so much lower than Rec709
100% IRE needs input reflectance 4609 which is 5.5 stops headroom for overexposure.
So what we have here is a shift of the black level from 0% to 7.3% and a compression of all tones over 18% this gives the washout look to V-LOG that is mistakenly interpreted as flat but it is not flat at all. In fact the master pedestal as it is known in video or black level is shifted. Another consequence of this formula is that VLOG under 18% IRE works exactly like standard gamma corrected Rec709 so it should have exactly the same performance in the darks with a range between 7.3% and 18% instead of 0-18%.
In terms of ISO measured at 18% reflectante V-LOG should have identical ISO value to any other photo style in your camera this means at given aperture and exposure time the ISO in a standard mode must match V-LOG.
When we look at the reality of V-LOG we can see that Panasonic sets 0 at a value of 50% IRE so generally ⅔ to 1 full stop overexposed this becomes obvious when you look at the waveform. As a result blacks are actually at 10% IRE and whites at 80% once a conversion LUT is applied.
Challenges of Log implementation
LOG conversion is an excellent method to compress a high dynamic range into a smaller bit depth format. The claim is that you can pack the full sensor dynamic range into 10 bits video. Panasonic made this claim for the GH5s and for the S1H, S5.
There is however a fundamental issue. In a consumer digital camera the sensor is already equipped with a digital to analog converter on board and this operates in a linear non log mode. This means the sensor dynamic range is limited to the bit depth of the analog to digital converter and in most cases sensors do not even saturate the on board ADC. It is true that ADC can also resolve portions of bits however this does not largely change the picture.
If we look at the sensor used in the S1H, S5 this is based on a Sony IMX410 that has saturation value of 15105 bits or 13.88 stops of dynamic range. The sensor of the GH5s which is a variant of Sony IMX299 has a saturation of 3895 (at 12 bits) or 11.93 stops.
None of the S1H, S5 or GH5s actually reaches the nominal dynamic range that the ADC can provide at sensor level. The sensor used by the GH5 has more than 12 stops dynamic range and achieves 12.3 EV of engineering DR, as the camera has 12 bits ADC it will resolve an inferior number of tones.
So the starting point is 12 or 14 stops of data to be digitally and not analogically compressed into 10 bits coding. Rec709 has a contrast ratio requirement of 1000:1 which is less than 10 stops dynamic range. This has not to be confused with bit depth. With 8 bits depth you can manage 10 stops using gamma compression. If you finish your work in Rec709 the dynamic range will never exceed log2(1000)=9.97 stops. So when you read that rec709 only has 6.5 stops of DR or similar it is flawed as gamma compression squeezes the dynamic range into a smaller bit depth.
When we look at a sensor with almost 14 stops of dynamic range the standard rec709 gamma compression is insufficient to preserve the full dynamic range as it is by default limited to 10 stops. It follows that logically LOG is better suited to larger sensors and this is where it is widely used by all cinema camera manufacturers.
In practical terms the actual photographic dynamic range (this is defined as the dynamic range you would see on a print of 10″ on the long side at arm length), the one you can see with your eyes in an image, is less than the engineering value. The Panasonic S5 in recent tests showed around 11.5 stops while the GH5S is around 10 and the GH5 9.5 stops of dynamic range. Clearly when you look at a step chart the tool will show more than this value but practically you will not see more DR in real terms.
This means that it is possible that a standard gamma encoded video in 10 bits can be adequate in most situations and nothing more is required. There is also a further issue with noise that the log compression and decompression produces. As any conversion that is not lossless the amount of noise increases: this is especially apparent in the shadows. In a recent test performed with a S5 in low light and measured using neat-video assessment V-Log was one of the worst performed in terms of SNR. The test involved shooting a color checker at 67 lux of ambient illumination and reading noise level on the 4 shadows and darks chips. Though this test was carried out at default setting it has to be noted that even increasing the noise reduction in V-LOG does not eliminate the noise in the shadow as this depends on how V-LOG is implemented.
The actual V-Log implementation
How does V-LOG really work? From my analysis I have found that V-Log is not implemented equally across cameras, this is for sure a dependency on the sensor performance and construction. I do not know how a Varicam camera is built but in order to perform the V-Log as described in the document you need a log converter before the signal is converted to digital. In a digital camera the sensor already has an on board ADC (analog to digital converter) and therefore the output is always linear on a bit scale of 12 or 14 bits. This is a fundamental difference and means that the math as illustrated by Panasonic in the V-LOG/V-Gamut documentation cannot actually be implemented in a consumer digital camera that does not have a separate analog log compressor.
I have taken a test shot in V-LOG as well as other standard Photo Styles with my Lumix S5 those are the RAW previews. V-LOG is exactly 2 2/3 stops underexposed on a linear scale all other parameters are identical.
What is happening here? As we have seen ISO values have to be the same between photo styles and refer to 18% middle grey however if you apply a log conversion to a digital signal this results in a very bright image. I do some wide field astrophotography and I use a tool called Siril to extract information from very dark images this helps visualise the effect of a log compression.
The first screenshot is the RAW file as recorded a very dark black and white image as those tools process separately RGB.
The second image shows the same RAW image with a logarithmic operator applied; this gives a very bright image.
Now if you have to keep the same middle grey value exposure has to match that linear image so what Panasonic does is to change the mapping of ISO to gain. Gain is the amplification on the sensor chip and has values typically up to 24-30 dB or 8 to 10 stops. While in a linear image the ISO would be defined as 100 at zero gain (I am simplifying here as actually even at 100 there will be some gain) in a log image zero gain corresponds to a different ISO value. So the mapping of ISO to gain is changed. When you read that the native ISO is 100 in normal mode and 640 in V-LOG this means that for the same gain of 0 dB a standard image looks like ISO 100 and a V-LOG image looks like ISO 640, this is because V-LOG needs less gain to achieve the same exposure as the log operator brightens the image. In practical terms the raw linear data of V-LOG at 640 is identical to an image taken at 100.
This is the reason why when a videographer takes occasional raw photos and leaves the camera in V-LOG the images are underexposed.
The benefit of the LOG implementation is that thanks to log data compression you can store the complete sensor information in a lower bit depth in our case this means going from 14 to 10 bits.
There are however some drawbacks due to the fact that at linear level the image was ‘underexposed‘, I put the terms in italic as exposure only depends on time and aperture of the lens, so in effect is lack of gain for which there is no term.
The first issue is noise in the shadows as those on a linear scale are compacted, as the image is underexposed: a higher amount of noise is present and this is then amplified by the LOG conversion. It is not the case that LOG does not have noise reduction, in fact standard noise reduction expects a linear signal gamma corrected and therefore could not work properly (try setting a high value in V-LOG on a S camera to see the results), the issue is with the underexposure (lack of gain) of the linear signal.
There are also additional side effects due to what is called black level range, I recommend reading on photonstophotos a great website maintained by Bill Claff. When you look at black levels you see that cameras do not really have pure black but have a range. This range results in errors at the lower scale of the exposure; the visible effect is colour bleeding (typically blue) in the shadows when there is underexposure. As V-LOG underexposed in linear terms you will have issues of colour bleeding in the shadows: those have been experienced by several users so far with no explanation.
The other side effect is that the LUT to decompress V-LOG remains in a 10 bit color space which was insufficient to store the complete dynamic range data and this does not change. So the LUT does not fully reverse the log compression in Panasonic case this goes into the V709 CineLike Gamma which is in a Rec709 gamma. As the full signal is not decompressed means that there are likely errors of hue accuracy so V-LOG does not have a better ability to reproduce accurate colors and luminance and this is the reason why even after a LUT is applied it needs to be graded. If you instead decompress V-LOG in a log space like Rec2020 HDR you will see that it does not look washed out at all and colors are much more vibrant as the receiving space has in excess of 20 stops.
Some users overexpose their footage saying they are doing ETTR. Due to the way log is implemented this means it will reach a clipping point sooner and therefore the dynamic range is no longer preserved. This is a possible remedy to reduce the amount of noise in low light however the log compression is not fully reversed by the LUT that is expecting middle grey exposure and therefore color and luminance accuracy errors are guaranteed. If you find yourself regularly overexposing V-LOG you should consider not using it at all.
Shadow Improvement and input referred noise
The Lumix cameras with dula gain sensor have a different behaviour to those without. This is visible in the following two graphs again from Bill Claff excellent website.
The first is the shadow improvement by ISO here you can see that while the GH5/G9 stay flat and are essentially ISO invariant, the GH5S and S5 that have a dual gain circuit have an improvement step when they go from low to high gain. What changes here is due to the way the sensors of the GH5s and S5 are constructed, the back illumination means that when the high gain circuit is active there is a material improvement in the shadows and the camera may even have a lower read noise at this ISO (gain) point than it had before because of this.
Another benefit of dual gain implementation is easier to understand when you look at input referred noise graphs. You can see that as the sensor enters the dual gain zone the input referred noise drops. Input referred noise means the noise that you would need to feed as an input to your circuit to produce the same noise as output. So this means when that step is passed the image will look less noisy. Again you can see that while the GH5 stays relatively flat the GH5s and S5 have a step improvement. Is it is not totally clear what happens in the intermediate zone for the GH5s possibly intermediate digital gain or more noise reduction is applied.
The combination of a certain type of sensor construction and dual conversion gain can be quite useful to improve shadows performance.
Do not confuse dual gain benefit with DR preservation, while dual gain reduces read noise it does not change the fact that the highlights will clip as gain is raised. So the effective PDR reduces in any case and is not preserved. The engineering DR is preserved but that is only useful to a machine and not to our eyes.
Now we are going to look at specific implementation of V-LOG in various camera models.
Front Illuminated 12 bits Sensors
Those are traditional digital cameras for photos and include the GH5, G9 for example. On those cameras you will see that the V-Log exposure shows a higher ISO value of 1 stop compared to other photo styles at identical aperture and shutter speed setting but the actual result is the same in a raw file so your RAW at 400 in VLOG is the same of another photo style at 200. This is a direct contradiction of Panasonic own V-Log model as the meter should read the same in all photo styles so something is going on here. As there is no underexposure it follows that there is no real log compression either. Those cameras are designed in a traditional way so low ISO (gain) is good high ISO (gain) is not. This is visible in the previous graphs.
Those screenshot show how the raw data of an image taken at ISO 250 in standard mode is identical to the V-LOG image and therefore shows how there is not LOG compression at all in the GH5. V-LOGL of the GH5 is therefore just a look and does not have any increase of dynamic range compared to other photo styles.
Is this version of V-LOGL more effective than other photo style with a compressed gamma like CineLikeD? According to Panasonic data CineLikeD has 450% headroom so it is already capable of storing the whole dynamic range that the GH5 can produce (450% means 12.13 stops vs 12.3 theoretical maximum).
In addition noise performance of V-Log is worse because all is doing is acting on shadows and highlights and not really doing any log conversion. The business case for acquiring a V-Log key on those cameras is limited if the objective was to preserve dynamic range as the camera already has this ability with photo styles included with the camera and moreover the V-LOG is not actually anything related to LOG compression otherwise the image would have needed to have less gain and would have shown underexposed. The fact that the camera is shooting at nominal ISO 400 means most likely that some form of noise reduction is active to counter the issue that V-Log itself introduces of noise in the shadows. So in this type of camera V-LOG is only a look and does not accomplish any dynamic range compression.
Back Illuminated 12 bits readout sensors
The cameras that have this technology are the GH5s and the BGH1, the back illumination gives the sensor a better ability to convert light into signal when illumination levels are low. Those cameras have actually a sensor with an 14 bits ADC but this is not used for video.
In order to decompose the procedure I have asked a friend to provide some RAW and Jpeg images in Vlog and normal. You can see that in the GH5s there is 1 stop underexposure and therefore a light form of log compression.
In the GH5s implementation the camera meters zero at the same aperture shutter and ISO in LOG and other photo styles and zero is 50% IRE so actually is 1 stop overexposed.
The procedure for V-Log in this cameras is as follows:
Meter the scene on middle grey + 1 stop (50%)
Reduce gain of the image 1 stop behind the scenes (so your 800 is 400 and 5000 is 2500)
Digital log compression and manipulation
As the underexposure is mild this means the log compression is also mild as it is only recovering 1 stop as the two effect cancels this is actually a balanced setting.
The IMX299 dual gain implementation was a bit messed up in the GH5s but has been corrected in the BGH1 with the values of 160 and 800. It is unclear what is happening to the GH5s and why Panasonic declared 400 and 2500 as the dual gain values as those do not correspond to sensor behaviour, perhaps additional on sensor noise reduction only starts at those values or just wanting to make a marketing statement.
Back Illuminated 14bits Sensors
Here we have the S1H and S5 that have identical sensors and dual gain structure.
The metering behaviour on the S series is the same as the GH5s so all photo styles result in identical metering. The examples were at the beginning of this post so I am not going to repeat them here.
Now the gain reduction is 2 and ⅔ stops which is significant. After this is applied a strong log compression is performed. This means that when you have ISO 640 on the screen the camera is actually at gain equivalent to ISO 100 and when you have 5000 is at 640 resulting in very dark images. In the case of the S5/S1H VLOG does offer additional dynamic range not achievable with other photo styles.
Interestingly V-Log on the S series does achieve decent low light SNR despite the strong negative gain bias. Here we can see that the Log implementation can be effective however other photo styles that do not reduce gain may be a better choice in low light as gain lifts the signal and improves SNR. It is also important to note that the additional DR of VLOG compared to other photo styles is in the highlights so it only shows on scenes with bright areas together with deep darks this was noted on dpreview and other websites.
Should you use V-LOG?
It looks like Panasonic is tweaking the procedure for each sensor or even camera as they go along. The behind the scenes gain reduction is really surprising however it is logical considering the effect of a log compression.
Now we can also see why Panasonic calls the GH5s implementation V-LOGL as the level of log compression is small only 1 stops as opposed to VLOG in the S series where the compression is 2 ⅔ stops. We have also seen that V-LOG, at least in a digital consumer camera with sensor with integrated ADC, has potentially several drawbacks and those are due to the way a camera functions.
Looking at benefits in terms of dynamic range preservation:
GH5/G9 and front illuminated sensor: None
GH5s/BGH1 back illuminated MFT: 1 stop
S5/S1H full frame: 2 ⅔ stops
What we need to consider is that changing the gamma curve can also store additional dynamic range in a standard video container. Dpreview is the only website that has compared the various modes when they reviewed the Panasonic S1H.
A particularly interesting comparison is with the CineLikeD photo style that according to Panasonic can store higher dynamic range and is also not affected by the issues of V-LOG in the shadows or by color accuracy problems due to log compression. The measures of dpreview show that:
On the GH5s V-LOG has 0.3 stops benefits over CineLikeD
On the S1H V-LOG has a benefit of 0.7 stops over CineLikeD2
Considering the potential issues of noise and color bleeding in the shadows together with hue accuracy errors due to the approximation of the V-LOG implementation I personally have decided not to use V-LOG at all for standard dynamic range but to use it for HDR footage only as the decompression of V-LOG seems to have limited to no side effects. In normal non HDR situations I have shot several clips with V-LOG but I never felt I could not control the scene to manage with other photo styles and the extra effort for a maximum benefit of 0.7 Ev is not worth my time nor the investment in noise reduction software or the extra grading effort required. As HDR is not very popular I have recently stopped using V-LOG altogether due to lack of support of HDR in browsers for online viewing.
Obviously this is a personal consideration and not a recommendation however I hope this post helps you making the right choices depending on what you shoot.
This write up is based on my analysis on Panasonic V-LOG and does not necessarily mean the implementation of other camera manufacturers is identical however the challenges in a digital camera are similar and I expect the solutions to be similar too.
In order to product HDR clips you need HDR footage. This comes in two forms:
Cameras have been shooting HDR since years the issue has been that no consumer operating system or display were capable of displaying it. The situation has changed as Windows 10 and Mac Os now have HDR-10 support. This is limited for example on Mac Os there is no browser support but the Tv app is supported, while on windows you can watch HDR-10 videos on YouTube.
You need to have in mind your target format because Log and HLG are not actually interchangeable. HLG today is really only Tv sets and some smartphones, HDR-10 instead is growing in computer support and is more widely supported. Both are royalty free. This post is not about what is the best standard is just about producing some HDR content.
The process is almost identical but there are some significant differences downstream.
Let me explain why this graph produced using the outstanding online application LutCalc show the output input relationship of V-LOG against a standard display gamma for rec709.
V-LOG -> PQ
Looking at the stop diagram we can appreciate that the curves are not only different but a lot of values differ substantially and this is why we need to use a LUT.
Once we apply a LUT the relationship between V-LOG and Rec709 is clearly not linear and only a small parts of bits fit into the target space.
We can see that V-Log fills Rec709 with just a bit more than 60% IRE so there will need to be a lot of squeezing to be done to fit it back in and this is the reason why many people struggle with V-Log and the reason why I do not use V-Log for SDR content.
However the situation changes if we use V-Log for HDR specifically PQ.
You can see that net of an offset the curves are almost identical in shape.
This is more apparent looking at the LUT in / out.
With the exception of the initial part that for V-Log is linear while PQ is fully logarithmic the curve is almost a straight line. As PQ is a larger space than that V-Log can produce on a consumer camera we do not have issues of squeezing bits in as PQ accommodates all bits just fine.
Similar to V-LOG HLG does not have a great fit into an SDR space.
The situation becomes apparent looking at the In/Out Lutted values.
We can see that as HLG is also a log gamma with a different ramp up 100% is achieved with even less bits that V-Log.
So really in pure mathematical terms the fit of log spaces into Rec709 is not a great idea and should be avoided. Note with the arrival of RAW video we still lack editors capable to work in 16 bit depth space like photo editors do and currently all processes go through LOG because they need to fit into a 10/12 bits working space.
It is also a bad idea to use V-Log for HLG due to the difference of the log curves.
And the graph demonstrates what I said at the beginning. You need to decide at the outset your output and stick to a compatible format.
Importing Footage in Final Cut Pro X 10.4.8
Once we have HLG or LOG footage we need to import it into a Wide Gamut Library, make sure you check this because SDR is default in FCPX.
HLG footage will not require any processing, but LUTs have to be applied to V-LOG as this is different from any Rec2100 target spaces.
The most convenient way is to go into Organise workspace select all clips than press the i button and select General. Apply the Panasonic V-Log LUT to all clips.
Creating a Project
Once all files have been handled as required we create our HDR-10 project which in final cut means Rec2020 PQ.
The following screenshots demonstrate the effect of the LUT on footage on a PQ timeline.
With the LUT applied the V-LOG is expanded in the PQ space and the colours and tones come back.
We can see the brightness of the scene is approaching 1000 nits and looks exactly we we experienced it.
Once all edits are finished and just as last step we add the HDR Tools to limit peak brightness to 1000 Nits which is a requirement of YouTube and most consumer displays. The Scope flex slightly with an automatic highlight roll-off.
Exporting the Project
I have been using Panasonic AVCI 400 mbps so I will export a master file using ProRes422 HQ if you use a lower bitrate ProRes 422 may be sufficient but don’t go lower as it won’t be HDR anymore.
YouTube and other devices use default settings for HDR-10 metadata so do not fill the mastering display nor content information it is not required and you would not know how to fill it correctly with exception of peak brightness.
Converting for YouTube
I use the free program handbrake and YouTube guidelines for upload to produce a compatible files. It is ESSENTIAL to produce an mp4 file otherwise your TV and YouTube may not be able to display HDR correctly avoid any other format at all costs.
The finished product can be seen here
SDR version from HDR master
There are residual issues with this process one is the production of an SDR version. This currently works much better for HLG than HDR-10 which is interesting because HLG is unsupported on any computer so if you produce HDR HLG you are effectively giving something decent to both audiences.
For HDR-10 YouTube applies their own one fits all LUT and the results can be really bad. You may experience oversaturated colours in some cases, dark footage in others, and some clips may look totally fine.
At professional level you would produce a separate SDR grade however it is possible to improve the quality of YouTube conversion using specific techniques I will cover in a separate post.
Grading in HDR is not widely supported the only tools available are scopes and Tone Mapping of your display. There is no concept of correct exposure for skin tones, in one scene those have a certain brightness and in another this changes again because this is not a 0-100% relative scale but goes with absolute values.
If you invested in a series of cinema LUT you will find none of them work and compresses the signal to under 100 nits. So there is less headroom for looks. There are other things you can do to give some vintage look like adding grain but you need to be careful as the incredible brightness of the footage and the details of 10 bits means if you push it up too much it looks a mess. Currently I am avoiding adding film grain and if I add it I blend it to 10%-20%.
One thing that is interesting is that Log footage in PQ does have a nice feel to it despite the incredible contrast. After all Log is a way to emulate film specifically Cineon, this is true for almost all log formats. Then you would have the different characteristics of each film stock, this is now our camera sensor and because most of them are made by Sony or Canon the clips tend to look very similar to each other nowadays. So if you want to have something different you need to step in the world of Red or ARRI but this is not in the scope of what I am writing here and what you my readers are interested in.
Am keeping a playlist with all my HDR experiments here and I will keep adding to it.
If you find this useful please donate using the button on the side and I will have a drink on you…Cheers!
As you have read, I have been at the forefront of HDR use at home. I have a total of 5 devices with HDR certification of which 2 supporting all standards all the way to Dolby Vision and 3 supporting at least HLG and HDR-10. The consumption of content is composed for most of Netflix or Amazon originals and occasional BBC HLG broadcasts that are streamed concurrently to live programs. So, it is fair to say I have some practical experience on the subject and two years ago I started writing about shooting HLG with the GH5. This was mostly limited by lack of editing capabilities on the display side, but recently Mac OS 10.15.4 has brought HDR-10 support that means you can see HDR signal on a compatible HDMI or DisplayPort device. This is not HLG but there are ways around it as I wrote in a recent post. This post makes some considerations on the issues of shooting HDR and why as of 2020 shooting SDR Rec709 with your Panasonic GH5 is still my preferred option for underwater video and not.
Real vs Theoretical Dynamic Range
You will recall the schematic of a digital camera from a previous post.
This was presented to discuss dual gain circuits but if you ignore the two gain circuits it remains valid. In this post we will focus on the ADC which stands for Analog to Digital Converter. Contemporary cameras have 12- and 14-bits ADC, typically 14 bits ADC are a prerogative of DSLR cameras or high-end cameras. If we want to simplify to the extremes the signal arriving to the ADC will be digitalised on a 12- or 14-bits scale. In the case of the GH5 we have a 12-bits ADC, it is unclear if the GH5s has a 14-bits ADC despite producing 14-bits RAW, for the purpose of this post I will ignore this possibility and focus on 12-bits ADC.
12-bits means you have 4096 levels of signal for each RGB channel this effectively means the dynamic range limit of the camera is 12 Ev as this is defined as Log10(4096)/Log10(2)=12. Stop wait a minute how is that possible? I have references that the Panasonic GH5 dynamic range is 13 Ev how did this become 12?
Firstly, we need to ignore the effect of oversampling and focus on 1:1 pixel ratio and therefore look at the Screen diagram that shows just a bit more than 12 Ev. We then have to look at how DxOMark measures dynamic range this is explained here. In real life we will not be shooting a grey scale but a coloured scene, so unless you are taking pictures of the moon you will not get much more than 12 stops in any scenarios as the colours will eat the data.
This was for what concerns RAW sensor data before de-mosaicing and digital signal processing that will further deteriorate DR when the signal is converted down to 10-bits even if a nonlinear gamma curve is put in place. We do not know what is really the useable DR of the GH5 but Panasonic statement when V-LOG was announced referenced 12 stops dynamic range using a logarithmic curve so we can safely conclude that the best case is 12 stops when a log curve is used and 10 for a gamma curve with a constant correction factor. Again, it is worth stressing that the 12 stops DR is the absolute maximum at the camera setting with 0 gain applied aka base or native ISO which for the GH5 is 200 corresponding to 400 in log modes.
Shooting HLG vs SDR
Shooting HLG with the GH5 or any other prosumer device is not easy.
The first key issue in shooting HLG is the lack of monitoring capabilities on the internal LCD and on external monitors. Let’s start with the internal monitor that is not capable to display HLG signals and relies on two modes:
Mode 1 : priorities the highlights wherever they are
Mode 2 prioritise the subject i.e. center of the frame
In essence you are not able to see what you get during the shot. Furthermore, when you set zebra to 90% the camera will be rarely reaching this value. You need to rely on the waveform, that is not user friendly in an underwater scene, or on the exposure meter. If you have a monitor you will find if you are carefully in the spec that the screens are rec709 so will not display the HLG gamma while they will correctly record the colour gamut. https://www.atomos.com/ninjav : if you read under HDR monitoring gamma you see BT.2020 that is not HDR is SDR. So you encounter the same issues albeit on a much brighter 1000 nits display that you have on the LCD and you need to either adapt to the different values of the waveform or trust the exposure meter and zebra that as we have said are not very useful as it take a lot to clip. On the other hand if you shoot an SDR format the LCD and external monitor will show exactly what you are going to get except you shoot in V-LOG, in this case the waveform and the zebra will need to be adjusted to consider that VLOG absolute max is 80% and 90% white is 60%. Once you apply a monitor LUT however, you will see exactly what you are going to get on the internal or external display.
Editing HLG vs SDR
In the editing phase you will be faced with similar challenges although as we have seen there are workarounds to edit HLG if you wish so. A practical consideration is around contrast ratio. Despite all claims that SDR is just 6 stops I have actually dug out the BT.709, BT.1886, BT.2100 recommendations and I this is what I have found.
Specifications of ITU display standards
In essence Rec709 has a contrast ratio of 1000 which means 9.97 Stops of DR and already allows for 8- and 10-bits colour. BT.1886 was issued to consider CRT screens no longer exist and this means that the DR goes to 10.97 stops. BT.2100 has a contrast ratio of 200000:1 or 17.61 stops of DR.
DisplayHDR Performance Standards
Looking at HDR monitors you see that, with the exception of OLED screens, no consumer devices can meet BT.2100 standards; so even if you have an HDR monitor in most cases is falling short of BT.2100 recommendation.
Our GH5 is capable of a maximum 12 stops DR in V-Log and maybe a bit more in HLG however those values are far below BT.2100 recommendations and more in line with BT.1886 recommendation. If we look at DxOMark DR charts we see that at ISO 1600 nominal that is in effect just above 800 the DR has fallen below 10 Ev. Consider that this is engineering DR practically speaking you are getting your 12 stops just at ISO 200 and your real HDR range is limited to 200-400 ISO range this makes sense as those are the bright scenes. Consider that log photo styles start at ISO 400 but this really translates to ISO 200 on this chart as well as exposure values. Unless you are shooting at low ISO you will get limited DR improvement. Underwater is quite easy to be at higher ISO than 200 and even when you are at 200 unless you are shooting the surface the scene has limited DR anyway. Generally, 10 stops are more than adequate as this is what we get when we produce a Jpeg from a RAW file.
I think the final nail in the coffin arrives when we look where the content will be consumed.
Typical Devices Performance
Phones have IPS screen with some exceptions and contrast ratio below 1000:1 and so do computer screens. If you share on YouTube you will know phones and computer constitute around 85% of playback devices. Tv are around 10% and a small part of those will be HDR. So other than your own home you will not find many HDR devices out there to give justice to your content.
10-bits vs 8 bits
It is best practice to shoot 10 bits and both SDR and HDR support 10 bits colour depth. For compatibility purposes SDR is delivered with 8 bits colour and HDR on 10 bits colour.
Looking at tonal range for RAW files on 8 Megapixels we see that the camera has 24 bits depth over RGB this means 8 bits per channel and 9 bits tonal range. Tonal range are grey levels so in short, the camera will not produce 10 bits colour bit will have more than 8 bits of grey tones which are helpful to counter banding but only at low ISO, so more useful for blue skies than for blue water. Considering that image for photo competitions are JPEGs and that nobody has felt the need for something more we can conclude that as long as we shot at high bitrate something as close to a raw format 8 bit for delivery are adequate.
Cases for HDR and Decision Tree
There are cases where shooting HLG can be meaningful those include snorkelling at the surface on bright days. You will not be going at depth so the footage will look good straight off the camera, likewise, for bright shots in the sun on the surface. But generally, the benefit will drop when the scene has limited DR or at higher ISO values where DR drops anyway.
What follows is my decision tree to choose between SDR and HDR and 10 bits vs 8 bits formats. I like my pictures and my videos to look better than life and I think editing adds value to the imaging although this is not an excuse for poor capture. There are circumstances where editing is less important, namely when the scene is amazing by itself and requires no extra help, or when I am looking at fast paced, documentary style scenes that do not benefit from editing. For the rest my preference remains for editing friendly formats and high bit rate 10 bits codec all intra. Recently I have purchased the V-Log upgrade and I have not found difficult to use or expose so I have included this here as possible option.
The future of HDR
Except a cinema like setting with dark surrounding and low ambient light HDR mass consumption remains challenging. Yes, you can have high peak brightness but not high contrast ratio and this can be obtained with SDR for most already. There is a lot of noise in the cinema community at present because the PQ curve is hard to manage and the work in post processing is multiplied, clearly PQ is not a way forward for broadcasting and HLG will prevail thanks to the pioneering efforts of the BBC but the lack of monitoring and editing devices means HLG is not going to fit cine like scenarios and little productions. It could be a good fit for a zero-edit shooter someone that like to see the scene as it was.
When marketing myths and incorrect information is netted out we realise that our prosumer devices are very far away from what would be required to shoot, edit and consume HDR. Like many other things in digital imaging is much more important to focus on shooting techniques and how to make the most of what we have, instead of engaging on a quest for theoretical benefits that may not exist.
It has been almost two years from my first posts on HLG capture with the GH5 https://interceptor121.com/2018/06/15/setting-up-your-gh5-for-hlg-hdr-capture/ and last week Apple released Catalina 10.15.4 that now supports HDR-10 with compatible devices. Apple and in general computer are still not supporting HLG and it is unlikely this is ever going to happen as the gaming industry is following VESA DisplayHDR standard that is aligned to HDR-10.
After some initial experiments with GH5 and HLG HDR things have gone quiet and this is for two reasons:
There are no affordable monitors that support HLG
There has been lack of software support
While on the surface it looks like there is still no solution to those issues, in this post I will explain how to grade HLG footage in Final Cut Pro should you wish to do so. The situation is not that different on Windows and DaVinci Resolve that also only support HDR-10 monitors but I leave it to Resolve users to figure out. This tutorial is about final cut pro.
A word about Vlog
It is possible to use Vlog to create HDR content however VLOG is recorded as rec709 10 bits. Panasonic LUT and any other LUT are only mapping the VLOG gamma curve to Rec709 so your luminance and colours will be off. It would be appropriate to have a VLOG to PQ LUT however I am not aware this exists. Surely Panasonic can create that but the VLOG LUT that comes with the camera is only for processing in Rec709. So, from our perspective we will ignore VLOG for HDR until such time we have a fully working LUT and clarity about the process.
Why is a bad idea to grade directly in HLG
There is a belief that HLG is a delivery format and it is not edit ready. While that may be true, the primary issue with HLG is that no consumer screens support BT.2020 colour space and the HLG gamma curve. Most display are plain sRGB and others support partially or fully DCI-P3 or the computer version Display P3. Although the white point is the same for all those colour spaces there is a different definition of what red, green and blue and therefore without taking into this into account, if you change a hue, the results will not be as expected. You may still white balance or match colours in HLG but you should not attempt anything more.
What do you need for grading HDR?
In order to successfully and correctly grade HDR footage on your computer you need the following:
HDR HLG footage
Editing software compatible with HDR-10 (Final Cut or DaVinci)
An HDR-10 10 bits monitor
If you want to produce and edit HDR content you must have compatible monitor let’s see how we identify one.
Finding an HDR-10 Monitor
HDR is highly unregulated when it comes to monitors, TVs have Ultra HD Premium Alliance and recently Vesa has introduced DisplayHDR standards https://displayhdr.org/ that are dedicated to display devices. So far, the Display HDR certification has been a prerogative of gaming monitors that have quick response time, high contrast but not necessarily high colour accuracy. We can use the certified list of monitors to find a consumer grade device that may be fit for our purpose: https://displayhdr.org/certified-products/
A DisplayHDR 1000 certified is equivalent to a PQ grading device as it has peak brightness of 1000 nits and minimum of 0.005 this is ideally what you want, but you can get by with an HDR-400 certified display as long as it supports wide colour gamut. In HDR terms wide gamut means covering the DCI-P3 colour space at least for 90% so we can use Vesa list to find a monitor that is HDR-10 compatible and has a decent colour accuracy. Even inside the HDR-400 category there are displays that are fit for purpose and reasonably priced. If you prefer a brand more orientated to professional design or imaging look for the usual suspects Eizo, Benq, and others but here it will be harder to find HDR support as usually those manufacturers are focussed on colour accuracy, so you may find a display covering 95% DCI-P3 but not necessarily producing a high brightness. As long as the device supports HDR-10 you are good to go.
I have a Benq PD2720U that is HDR-10 certified, has a maximum brightness of 350 nits and a minimum of 0.35, it covers 100% sRGB and REC709 and 95% DCI-P3, so is adequate for the task. It is worth nothing that a typical monitor with 350-400 nits brightness offers 10 stops of dynamic range.
In summary any of this will work if you do not have a professional grade monitor:
Search professional display specifications for HDR-10 compatibility and 10 bits wide gamut > 90% DCI-P3
Final Cut Pro Steps
The easy way to have HDR ready content with the GH5 is to shoot with the HLG Photo Style. This produces clips that when analysed have the following characteristics with AVCI coded.
Limited means that it is not using the full 10 bits range for brightness you do not need to worry about that.
With your material ready create a new library in Final Cut Pro that has a Wide Gamut and import your footage.
As we know Apple does not support HLG so when you look at the Luma scope you will see a traditional Rec709 IRE diagram. In addition, the ‘Tone Mapping Functionality’ will not work so you do not have a real idea of colour and brightness accuracy.
At this stage you have two options:
Proceed in HLG and avoid grading
Convert your material in PQ so that you can edit it
We will go on option 2 as we want to grade our footage.
Create a project with PQ gamut and enter your display information in the project properties. In my case the display has a minimum brightness of 0.35 nits and max of 350 and it has P3 primaries with a standard D65 white point. It is important to know those parameters to have a good editing experience otherwise the colours will be off. If you do not know your display parameters do some research. I have a Benq monitor that comes with a calibration certificate the information is right there. Apple screens are typically also P3 with D65 white point and you can find the maximum brightness in the specs. Usually around 500 nits for apple with minimum of 0.5 nits. Do not enter Rec2020 in the monitor information unless your monitor has native primaries in that space (there are almost none). Apple documentation tells you that if you do not know those values you can leave them blank, final cut pro will use the display information from colour sync and try a best match but this is far from ideal.
For the purpose of grading we will convert HLG to PQ using the HDR tools. The two variants of HDR have a different way to manage brightness so a conversion is required however the colour information is consistent between the two.
Please note that the maximum brightness value is typically 1000 Nits however there are not many displays out there that support this level of brightness, for the purpose of what we are going to do this is irrelevant so DO NOT change this value. Activate tone mapping accessible under the view pull down in the playback window this will adapt the footage to your display according to the parameters of the project without capping the scopes in the project.
Finalising your project
When you have finished with your editing you have two options:
Stay in PQ and produce an HDR-10 master
Delete all HDR tools HLG to PQ conversions and change back the project to HLG
If you produce an HDR-10 master you will need to edit twice for SDR: duplicate the project and apply the HDR tool from HLG to SDR or other LUT of your choice.
If you stay in HLG you will produce a single file but is likely that HDR will only be displayed on a narrower range of devices due to the lack of support of HLG in computers. The HLG clip will have correct grading as the corrections performed when the project was in PQ with tone mapping will survive the editing as HLG and PQ share the same colour mapping. The important thing is that you were able to see the effects of your grade.
In my case I have an HLG TV so I produce only one file as I can’t be bothered doing the exercise two times.
The steps to produce your master file are identical to any other projects, I recommend creating a ProRes 422 HQ master and from there other formats using handbrake. If you change your project back to HLG you will get a warning about the master display you can ignore it.
Am not getting into ambient light filters but there are articles on that too.
Now I wanted to discuss editing as I see many posts on line that are plain incorrect. As it is true for photos you don’t edit just looking at an histogram. The histogram is a representation of the average of the image and this is not the right approach to create strong images or videos.
You need to know how the tools work in order to do the appropriate exposure corrections and colour corrections but it is down to you to decide the look you want to achieve.
I like my imaging video or still to be strong with deep blue and generally dark that is the way I go about it and is my look however the tools can be used to have the look you prefer for your materials.
In this YouTube tutorial I explain how to edit and grade footage produced buy the camera and turn it into something I enjoy watching time and time again.
I called this clip Underwater Video Colour Correction Made Easy as it is not difficult to obtain pleasing colours if you followed all the steps.
A few notes just to anticipate possible questions
Why are you not looking to have the Luma or the RGB parades at 50% of the scale?
50% of the IRE scale is for neutral grey 18% I do not want my footage to look washed out which is what happens if you aim at 50%.
2. Is it important to execute the steps in sequence?
Yes. Camera LUT should be applied before grading as they normalise the gamma curve. In terms of correction steps setting the correct white balance has an influence on the RGB curves and therefore needs to be done before further grading is carried out.
3. Why don’t you correct the overall saturation?
Most of the highlights and shadows are in the light grey or dark grey areas. Saturating those can lead to clipping or noise.
4. Is there a difference between using corrections like Vibrancy instead of just saturation?
Yes saturation shifts equally the colours towards higher intensity vibrancy tends to stretch the colours in both direction.
5. Can you avoid an effect LUT and just get the look you want with other tools?
Yes this is entirely down to personal preference.
6. My footage straight from camera does not look like yours and I want it to look good straight away.
That is again down to personal preference however if you crush the blacks or clip the highlights or introduce a hue by clipping one of the RGB channels this can no longer be remediated.
I hope you find this useful wishing all my followers a Merry Xmas and Happy 2020.