In addition Black Magic design have just release the public beta of DaVinci Resolve 18.5. With this update you can now use the Raw controls in the Grading room to control the ISO/White Balance/Tint etc of S-Log3 footage from the FX series cameras. This makes it so easy to adjust for any exposure offsets. https://www.blackmagicdesign.com/support/family/davinci-resolve-and-fusion
What do the zebras measure when shooting S-Log3 using the CineEI modes in the FX3 and FX30?
The convention for zebras with the majority of cameras is that zebras are a viewfinder applied measurement. As such they almost always measure the “viewfinder” image. As the LCD on the FX series cameras is in effect the viewfinder, the zebras measure what you see on that screen. So, when you have a LUT on, the zebras measure the LUT, not the S-Log3.
Common ways to use the zebras include measuring skin tones, which for the default s709 LUT will be somewhere in the region of 60% depending on the face brightness. You could also use the LUT’s to measure the brightness of a white card or white piece of paper which should be around around 81% for a proper white card or 83% for white paper.
You could also use Zebras to indicate when you are close to clipping Depending on the LUT that you are using the peak LUT output will typically be at 100%, so a common usage would be to have Zebra 2 (which measures from the zebra point and everything above) set to a touch below 100 to act as a clipping indicator. BUT it must also be remembered that depending on the Exposure Index in most cases the LUT will have a lower highlight range than the S-Log3 recordings. So, when your highlights hit 100% on the LUT there may still be available headroom in the S-Log3 recordings. If you end up backing off your exposure every time the LUT clips you may be missing out on the full recording range and un-necessarily bringing the mids and shadows down. So, my preference is to measure the exposure of a white card or skin tones and to get the mid range and shadows right, rather than obsessing over small amounts clipping.
The s709 LUT does fit the full highlight range of the S-Log3 into it’s output. But as there is only a tiny difference between +5 and +6 stops (approx 1.5%) it is very difficult to determine what is clipped and what is 1 stop below clipping. +4 stops above middle grey is output at 93% and +6 above middle grey is at 98% so it becomes very difficult to see what is really going on in the highlights via the LUT when the top 2 stops are crammed into just 5% of the recording range. Zebra 2 set to 95% (for example) would appear over 1.5 stops below clipping, even if set to 97% zebras will show almost a full stop below clip.
It is one of the frustrations of the FX3/FX30 that there is no way to monitor via the LUT and measure the S-Log3 at the same time.
For some reason many people now believe that the only way you can shoot with S-Log3 is by “over exposing” and very often by as much as almost 2 stops (1.7 stops is often quoted).
When Sony introduced the original A7S, the FS5, F5, F55 and FS7 shooting S-Log3 with these cameras was a little tricky because the sensors were quite noisy when used at the relatively high base ISO’s of these cameras. When exposed according to Sony’s recommendation of 41% for middle grey and 61% for a white card the end result would be fairly noisy unless you added a good amount of post production noise reduction. As a result of this I typically recommended exposing these particular cameras between 1 and 2 stops brighter than the base level. If using the F5 or FS7 I would normally use 800EI which would lead to an exposure +1.3 stops brighter than base. This worked well with these cameras to help control the noise, but did mean a 1.3 stop loss of highlight range. In other examples I used to recommend exposing a white card at white at 70% which would equate to an exposure a touch over 1 stop brighter than the base level.
With the introduction of the original Venice camera and then the FX9 we got a new generation of much lower noise sensors with dual base ISO’s. It soon became clear to me that these new cameras didn’t normally need to be exposed more brightly than the Sony recommended levels when using their low base ISO’s and even at their high base ISO’s you can typically get perfectly acceptable results without shooting brighter, although sometimes a small amount of over exposure or a touch of noise reduction in pots might be beneficial. No longer needing to expose more brightly brought with it a useful increase in the usable highlight range, something the earlier cameras could struggle with.
Then the A7S3, FX6 and FX3 came along and again at the lower of their base ISO’s I don’t feel it is necessary to shoot extra bright. However at the 12,800 high base ISO there is a fair bit more noise. So I will typically shoot between 1 and 2 stops brighter at the high base ISO to help deal with the extra noise. On the FX6 and FX3 this normally means using between 6400 and 3200 EI depending on the scene being shot.
Even though I and many others no longer advocate the use of extra bright exposures at the lower base ISO’s with these newer cameras it really does surprise me how many people believe it is still necessary to shoot up to 2 stops over. It’s really important to understand that shooting S-Log3 up to 2 stops over isn’t normal. It was just a way to get around the noise in the previous cameras and in most cases it is not necessary with the newer cameras.
Not having to shoot brighter means that you can now use the Viewfinder Display Gamma Assist function in the A7S3, A1 or the FX9 (for those times you can’t use a LUT) to judge your exposure with confidence that if it looks right, it most likely will be right. It also means that there is no longer any need to worry about offset LUT’s or trying to correct exposure in post before applying a LUT.
Of course, you can still expose brighter if you wish. Exposing brighter may still be beneficial in scenes with very large shadow areas or if you will be doing a lot of effects work. Or perhaps simply want an ultra low noise end result. But you shouldn’t be terrified of image noise. A little bit of noise is after all perfectly normal.
And one last thing: I don’t like the use of the term “over exposing” to describe shooting a bit brighter to help eliminate noise. If you have deliberately chosen to use a low EI value to obtain a brighter exposure or have decided to expose 1 stop brighter because you feel this will get you the end result you desire this is not (in my opinion) “over exposure”. Over exposure generally means an exposure that is too bright, perhaps a mistake. But when you deliberately shoot a bit brighter because this gets you to where you want to be this isn’t a mistake and it isn’t excessive, it is in fact the correct exposure choice.
I have updated my guide to the FX6’s CineEI mode to ensure it is up to date and compatible with any changes introduced in the Version 3 firmware update. The revised and updated guide includes new graphics that I hope will make the CineEI mode easier to understand for those completely new to shooting S-Log3 and the Sony FX6.
If you are struggling to get to grips with CineEI in the guide I take a step by step approach to using S-Log3 on it’s own without any LUT’s or EI offsets, then introducing the s709 LUT at the base EI and then show how you use different EI levels to offset you exposure. There are suggested exposure levels for both white and grey cards as well as skin tones.
I’ve been getting a lot of questions about the new FX3 firmware update. So, I thought I would put my answers to the questions here in one place. But before I get to my notes on what the firmware does, I will just say that if you are a Mac user, I recommend trying to borrow a PC to do the update. It is much much easier to do the update with a PC than a Mac! The firmware update is well worth doing. At first it might appear that the update makes it impossible to do some things the camera did before, but, if you follow my notes you will see that this is not actually the case.
What is the base ISO for S-Log3 in version 2? In the CineEI and CineEI Quick modes the base ISO defaults to 800/12800 ISO. This is different to before, but brings the FX3 in line with the other Sony Cinema line cameras and most other current digital cinema cameras. When not using the dedicated CineEI modes the base ISO for S-Log3 seems to revert back to 640 ISO as indicated by the way the camera adds a pair of bars, above and below the ISO indication from 500 ISO and down, to warn that you are below the native ISO.
Help, I can’t output 4K/UHD and record 4K/UHD internally while using the CineEI modes! It takes a lot of extra processing power to apply the LUT’s to the preview image while recording S-Log3. Unfortunately this seems to mean that there is no longer enough processing power to both record internal 4k/UHD and output 4K/UHD and have LUT’s at the same time. You can record internal 4K and 4K output raw, that’s one option. And you can record 4K and output HD. But if you need to record 4K/UHD internally and output 4K/UHD S-log3 you will need to come out of the cameras log mode.
How do you shoot S-Log3 when not using the Log modes? When you are not using the Log modes you will find that the old S-Log3 and S-Log2 picture profiles (7,8 and 9) are missing. However you can still go into any of the other picture profiles and change the gamma to S-Log3 and the color mode to S-Gamut3.cine or S-Gamut3. S-Log2 has been removed and is no longer available, but as S-Log2 is incapable of recording the full dynamic range of the FX3 this isn’t a big deal. Shooting S-Log3 this way allows you to record 4K/UHD internally and output 4K/UHD over the HDMI as in the previous version 1 firmware. I suspect that PP7/8/9 were removed simply to encourage users to use the dedicated log modes where everything is fully optimised for log rather than using a picture profile where any ISO can be used or other settings changed that may degrade the log.
What does “Embed LUT LUT File” do? When Embed LUT File is enabled the camera stores the LUT used in the “Private”, “M4ROOT”, “General” metadata folder on the recording card. In addition metadata about the LUT and the chosen exposure index is saved in the clip file. The LUT is NOT BAKED IN to the file, the recording remains as S-Log3. When you import the clip into the latest version of Sony’s Catalyst Browse software the LUT you used when shooting is automatically applied to the clip as well as the correct exposure offset for the Exposure Index used. The end result is the clip looks exactly the same in Catalyst Browse as it did on the cameras LCD when you were shooting. But because it is still an S-Log3 recording, you can still manipulate it as much as before and if you want you could use a different LUT in post. Hopefully in the future other edit and grading software will also read this metadata and apply the LUT automatically, this is really how this should all work (hope the FX6/FX9 get the same functionality).
How do I load a custom LUT into the FX3 camera? Start with an empty SD card and format the card in the camera. This will create the necessary folders needed for the LUT on the card. The FX3 accepts 33x 3D cube LUTS, this is the most commonly found LUT format. Next copy your chosen LUT to the “PRIVATE”, “SONY”, “PRO”, “LUT” folder. Then put the card into the camera and go to the menu “Exposure/Color”, “Color/Tone”, “Manage User LUTs” option. From here you will first chose a User memory slot to load the LUT into. You will then be prompted to choose the SD card that you saved the LUTs to, and then LUT you wish to load from the card. The LUT will be saved to the slot chosen – the original LUT name is kept, but if the name is too long it will be abbreviated. Once the LUT has been loaded into the camera you can then select it from the new Home Menu – page 1. You can save up to 16 user LUTs.
How do I bake in a LUT? To bake in a LUT you have to come out of the cameras dedicated Log shooting mode. In the normal shooting mode if you go to the menu’s “Exposure/Color”, “Color/Tone”, “Picture Profile” page you will see that as well as the picture profiles, a little lower down you will find 4 “PPLUT” settings. These initially correspond to the first 4 user LUT memories and allow you to select those LUTs as a baked in look. But if you have saved more than 4 user LUTs do not despair. You can go into the “PPLUT” setting and if you select “Basic Look” you can select any of your saved user LUTs.
What do the Zebras or histogram measure in the CineEI mode? The Histogram and zebras measure the brightness of the LUT when using the CineEI mode. Do note that when correctly exposed the s709 LUT will be a touch darker than S-Cinetone or normal Rec-709.
Average Skin Tones
90% Reflectivity white card (add 2-3% for white paper).
Will the A7S3 get the same firmware? As far as I know, no it will not. It is my understanding that this firmware is specifically for the FX3 as the FX3 is sold as a part of the Cinema Line and primarily as a video camera. The A7S3 is not part of the cinema line and is sold primarily as a photo camera that also shoots great video.
The smallest camera in Sony’s Cinema Line, the FX3 has a new, massive firmware update. Firmware version 2 adds a conventional CineEI mode as well as a “quick” CineEI mode (automatically switches the base ISO depending on the chosen EI value) for shooting S-Log3 and raw with the ability to monitor using custom LUTs. Additionally, if you wish you can also bake in you favourite LUT to your recordings. The firmware update also makes it possible to input timecode by using an special adapter cable that plugs into the cameras usb/multifunction port.
In the movie shooting mode the cameras on screen overlays are now moved above and below the main image area so that the images you are shooting are not obstructed by text or icons. This is really nice touch.
This update brings the FX3 into much closer functional alignment with the rest of the cinema line. Two make it all work the menu system has also been overhauled and a function menu can be quickly accessed by swiping the cameras touch screen.
Do not that this firmware does remove S-Log2 and that the camera will be reset to it’s factory defaults when the upgrade is performed. As far as I know the A7S3 will not get a similar update as this is not part of the Cinema Line. The firmware update is available for download from the Sony website. https://www.sony.co.uk/electronics/support/interchangeable-lens-camcorders-ilme-series/ilme-fx3/downloads
This is a question that comes up a lot. Especially from those migrating to a camera with a CineEI mode from a camera without one. It perhaps isn’t obvious why you would want to use a shooting mode that has no way of adding gain to the recordings.
If using the CineEI mode shooting S-log3 at the base ISO, with no offsets or anything else then there is very little difference between what you record in Custom mode at the base ISO and CineEI at the base EI.
But we have to think about what the CineEI mode is all about. It’s all about image quality. You would normally chose to shoot S-Log3 when you want to get the highest possible quality image and CineEI is all about quality.
The CineEI mode allows you to view via your footage via a LUT so that you can get an appreciation of how the footage will look after grading. Also when monitoring and exposing via the LUT because the dynamic range of the LUT is narrower, your exposure will be more accurate and consistent because bad exposure looks more obviously bad. This makes grading easier. One of the keys to easy grading is consistent footage, footage where the exposure is shifting or the colours changing (don’t use ATW with Log!!) can be very hard to grade.
Then once you are comfortable exposing via a LUT you can start to think about using EI offsets to make the LUT brighter or darker. When the LUT is darker you open the aperture or reduce the ND to return the LUT to a normal looking image and vice versa with a brighter LUT. This then changes the brightness of the S-log3 recordings and you use this offsetting process to shift the highlight/shadow range as well as noise levels to suit the types of scenes you are shooting. Using a low EI (which makes the LUT darker) plus correct LUT exposure (the darker LUT will make you open the aperture to compensate) will result in a brighter recording which will improve the shadow details and textures that are recorded and thus can be seen in the shadow areas. At the same time however that brighter exposure will reduce the highlight range by a similar amount to the increase in the shadow range. And no matter what the offset, you always record at the cameras full dynamic range.
I think what people misunderstand about CineEI is that it’s there to allow you to get the best possible, highly controlled images from the camera. Getting the best out of any camera requires appropriate and sufficient light levels. CineEI is not designed or intended to be a replacement for adding gain or shooting at high recording ISOs where the images will be already compromised by noise and lowered dynamic range.
CineEI exists so that when you have enough light to really make the camera perform well you can make those decisions over noise v highlights v shadows to get the absolute best “negative” with consistent and accurate exposure to take into post production. It is also the only possible way you can shoot when using raw as raw recordings are straight from the sensor and never have extra gain added in camera.
Getting that noise/shadow/highlight balance exactly right, along with good exposure is far more important than the use of external recorders or fatter codecs. You will only ever really benefit fully from higher quality codecs if what you are recording is as good as it can be to start with. The limits as to what you can do in post production are tied to image noise no matter what codec or recording format you use. So get that bit right and everything else gets much easier and the end result much better. And that’s what CineEI gives you great control over.
When using CineEI or S-Log3 in general you need to stop thinking “video camera – slap in a load if gain if its dark” and think “film camera – if its too dark I need more light”. The whole point of using log is to get the best possible image quality, not shooting with insufficient light and a load of gain and noise. It requires a different approach and completely different way of thinking, much more in line with the way someone shooting on film would work.
What surprises me is the eagerness to adopt shutter angles and ISO ratings for electronic video cameras because they sound cool but less desire to adopt a film style approach to exposure based on getting the very best from the sensor. In reality a video sensor is the equivalent of a single sensitivity film stock. When a camera has dual ISO then it is like having a camera that takes two different film stocks. Adding gain or raising the ISO away from the base sensitivity in custom mode is a big compromise that can never be undone. It adds noise and decreases the dynamic range. Sometimes it is necessary, but don’t confuse that necessity with getting the very best that you can from the camera.
I’ve added some updates to my guide to using the Cine EI Mode in the FX6 (towards the bottom) to cover the strange playback behavior where the EI levels are reversed. This can result in some very misleading brightness levels during playback that might make you think you exposed incorrectly. https://www.xdcam-user.com/2020/12/a-guide-the-the-fx6s-cineei-mode/
I have already done this a few times, but having seen some other tests suggesting the FX6’s ISO ratings were incorrect. So I decided to re-confirm my previous findings, which is that the ratings Sony give their cameras is correct. For the test I used a DSC labs exposure calibration chart which is an extremely accurate 18%/90% reflectivity chart and my trusty Sekonic light meter. As you can see at both 800 ISO and 12,800 ISO the light meters indicated exposure settings perfectly match the camera’s ISO ratings, shutter speed and aperture. For the 12,800 ISO test, as my light meter doesn’t go up to 12,800 ISO I set the light meter to 6400 ISO which is one stop lower than the cameras 12,800. The light meter indicated f11 which is one stop below the f16 required by the camera – confirming that the ISO rating is correct.
The FX6’s CineEI mode is designed to make shooting using S-Log3 or raw easy and straightforward. It optimises the camera so that settings such as the recording ISO, noise reduction and sharpening are all optimised for recording the highest possible quality S-Log3 or raw material with the largest possible dynamic range.
It makes sure that the S-Log3 or raw recordings are optimised for grading. In addition you can use a LUT (Look Up Table) in the viewfinder or on the HDMI/SDI output to provide a close approximation of how your footage will look after it’s been graded and this LUT will also to assist you in getting the exposure exactly right.
HINT: What is a LUT? A LUT is a simple Look Up Table of input values that represent different levels in the recording format (in this case S-Log3) and then converts those input values to new output values that are appropriate for the monitor or display range you are using. This conversion can included stylised adjustments to give the output image a specific look. A LUT can be applied to S-Log3 material to convert it so that it looks correct on a normal viewfinder or monitor.
To use the Cine EI mode correctly you must monitor what you are shooting via a LUT. Once you have a LUT enabled and you are viewing the LUT, either in the viewfinder or on a monitor an exposure offset can be applied to the LUT to make it darker or brighter than normal. This LUT brightness offset is used to allow you to deliberately offset how bright the recordings are, this is the “EI” or Exposure Index part of CineEI. More on that later.
BUILT IN LUTS
The FX6 has 3 built in LUTs, s709, 709(800) and S-Log3. In addition to the built in LUTs you can load your own “user MLUTs” into the camera as what the FX6 calls “Base Looks”. This makes this a very flexible and capable system. Sony refer to LUTs in the FX6 as MLUT’s or Monitor Look Up Tables. MLUTs = LUT’s they are not different.
Loading Your Own LUTs.
If you want to load you own LUTs into the camera these must be 3D Cube LUT’s and should be placed in the
— Private : SONY : PRO : LUT —
folder of an SD card or CFExpress card that has been formatted in card slot 2 of the FX6 (the lower slot). The LUT should be 17x or preferably 33x cube LUT designed for use with S-Log3 and SGamut3.cine. They are loaded via the main menu PAINT – BASE LOOK page.
As your material will require grading in post production, if you are shooting UHD or 4K you should NOT use XAVC-L because in UHD/4K XAVC-L is 8 bit 4:2:0. A much better choice is XAVC-I which is always 10 bit 4:2:2 and/or raw.
FIXED RECORDING ISO.
Once the camera is set to use the CineEI mode the recording sensitivity is fixed to either 800 ISO when in Lo Base sensitivity or 12,800 ISO when the camera is set to Hi Base sensitivity. These values cannot be changed and your recordings will always take place at one of these sensitivity levels.
Note: ISO and EI are not the same thing, even though they use similar numbers. ISO is very specifically the sensitivity of the camera, it is a measure of the sensors response to light. EI (Exposure Index) is a camera setting that alters the cameras EXPOSURE settings, EI does not change the sensitivity of the camera in any way.
ENABLE A MLUT (LUT).
To take full advantage of the Cine EI mode the next step is to enable a MLUT for the viewfinder and also optionally for the HDMI and SDI outputs. YOU MUST ENABLE A MLUT FOR CINE EI TO WORK.
My recommendation is as a minimum to enable a MLUT for the viewfinder. If you wish to record S-Log3 to an external recorder then you should not add a MLUT to the SDI/HDMI output. But if you are using an external monitor purely for monitoring it may be desirable to enable an MLUT for the SDI/HDMI output.
The default MLUT is Sony’s s709 LUT. This is the same LUT as used by the Venice digital cinema camera. s709 is designed to be a starting point for a film style look. To achieve this film style look it uses brightness levels more commonly found in feature films rather than the levels normally used in the majority of regular TV shows.
LUT EXPOSURE LEVELS
There are some important things to understand about different MLUTs and Base Looks. Each MLUT/Look will have it’s own optimum brightness levels. They will not all be the same. Some will be brighter or darker than others when exposed correctly, so it’s vital that you understand what levels any MLUT that you chose to use needs to be exposed at.
Another MLUT that the FX6 includes is Sony’s 709(800) LUT. This MLUT is more closely aligned with the levels used in normal TV productions, so it looks quite different to s709 and has very different brightness levels when exposed correctly.
The chart below gives the “correct” exposure values for S-Log3 as well as some guide values based on my own measurements for the s709 and 709(800) MLUTs found in the FX6.
Average Skin Tones
90% Reflectivity white card (add 2-3% for white paper).
MEASURING THE EXPOSURE.
There are many ways to measure your exposure when shooting using S-Log3 and MLUT’s. You could choose to use a light meter, in which case the light meter would be set to match the EI (Exposure Index) value set in the camera.
You can just look at the image in the viewfinder and judge when it looks right. Most of the time this is going to be OK, but it isn’t particularly accurate and if shooting outside in bright sunshine it may be difficult to see an unshaded LCD screen correctly.
My preferred method is to use a white card or grey card and then use the cameras built in video signal monitor and the waveform display to actually measure the brightness of the grey card or white card.
Note: When referring to a “white” exposure this means the exposure level of a white card that reflects 90% of the light that falls on it. It is not how bright your highlights are, or how bright clouds are. It is the brightness of a diffuse white card. A piece of white paper or a white shirt can be used if you don’t have a proper white card, but be aware that white printer paper or white fabrics are treated with brightening agents to make them look “bright” so white paper and white fabrics will be a little brighter, perhaps 94% reflectivity compared to 90% of a proper white card and this should be allowed for.
The Waveform Display.
If you are not familiar with a waveform display it is actually really easy to understand. The bottom of the waveform is black and the very top is 109%, the brightest that the camera can ever record to.
The left hand side is the left of the video image and the right is the right side of the video image. The thin grey reference lines across the waveform display are at 0% (the darkest a video image should ever normally be), 25%, 50%, 75% and 100%.
In addition the FX6’s waveform display includes 2 yellow lines. The position of these yellow lines is determined by the levels that the cameras zebras are set to. By default the lower yellow line will be at 70% to match Zebra 1 and the upper line at 100% to match zebra 2.
WHAT ARE YOU MEASURING?
The waveform display measures the signal that is on the HDMI and the SDI output. So when you turn on the MLUT for the HDMI/SDI it is the levels of the MLUT that are being measured. If you don’t have an MLUT enabled for the SDI/HDMI then you will be measuring the recorded S-Log3 level. What the waveform is measuring is indicated just above the waveform display, in the example above we can see it is indicating LUT s709, so we are measuring the s709 LUT.
UNDERSTANDING HOW IT ALL WORKS.
To make it easier to understand how CineEI works I find it easier to start by turning OFF the LUT for the SDI and HDMI and measuring the exposure of the S-Log3. If you do this when the the Exposure Index (EI) is set so that it is equal to the Recording or Base ISO then you can use a white card or piece of white paper to establish the correct exposure for the S-Log3. Once you have done that you can then enable the MLUT and check the exposure of the LUT. So, lets see how we do that:
FIRST CHECK AND SET THE EXPOSURE INDEX LEVELS.
With the cameras base ISO set to low / 800 ISO I recommend that you set the EI levels in the main menu SHOOTING – ISO/Gain/EI as follows:
ISO/GAIN BUTTON and CHANGING THE EI:
When using the CineEI mode you can change the EI value several ways. The most commonly used ways will likely be via the L/M/H ISO/Gain switch or by pressing the ISO/Gain button and then using the multi-function dial (MFD) to change the EI. Do note that when you use the multi-function dial or Direct Menu to change the EI this new EI setting changes the preset value associated with the current position of the L/M/H switch.
Personally I do not usually set an Exposure Index value that is higher than the base recording ISO value. The reason for this is that as you will see later, if you record using a high EI value your images will be noisy and grainy and could be very difficult to grade. Because you don’t ever see your final results until you get into post production, if you accidentally record noisy log you won’t really know how bad the footage will be until it is perhaps too late to do anything about it. So I set the EI for the Low Base 800 ISO as H>800EI, M>400EI, L>200EI. The difference between each of these EI’s is one stop and sticking to exact 1 stop increments makes it easier when you are checking any exposure changes.
For the 12,800 High base ISO I set the EI to H>12800EI, M>6400EI, L>3200EI.
FOR THIS EXAMPLE START AT LOW BASE/800 ISO and 800 EI.
By using the same EI as the base recording ISO there will be no offset or difference between the aperture, ND or shutter speed settings used for the correct exposure of the LUT and the correct, or “base exposure” for the S-Log3. Expose the LUT correctly and the S-Log3 will be also be normally exposed. Expose the S-Log3 normally and the LUT will look correct.
FOR THIS EXAMPLE LET’S START WITH THE SDI/HDMI LUT OFF.
For this example I am going to start with the LUT OFF for the SDI and HDMI, this way the waveform display will be measuring the S-Log3. Just above the waveform it should say SG3C/Slog3, telling you the waveform is measuring the S-Log3.
Referring to the table of exposure levels earlier in this article we can see that the correct exposure for S-Log3 using a white card (90% reflectivity white) is 61% – if using a normal piece of printer paper I suggest using a value a little higher (around 63%) as white paper tends to be a little brighter than a proper white test card. So, when measuring the S-Log3 we want to expose a white card at 61%. We can use the cameras zebras to help us find 61%.
SETTING ZEBRA 1 TO 61%
To make finding where 61% is on the waveform I recommend setting Zebra 1 to 61% so that the lower of the two yellow zebra lines on the waveform display is at 61%.
So now when checking the exposure of a white card when the waveform is measuring the S-Log3, it is simply a case of adjusting the exposure until the white card is at the same level as the 61% line. Alternately you could use an 18% grey card, in which case you would set Zebra 1 to 41%, however there are often times when I forget my grey card but I almost always have a piece of paper somewhere.
So now we know that the S-Log3 is correctly exposed lets turn ON the LUT for the SDI and HDMI outputs and check the exposure level of the s709 LUT (or any other LUT that you wish to use – by setting the S-Log3 exposure first, you can then determine the correct exposure level of any LUT that you might wish to use).
NOW TURN ON THE SDI/HDMI LUT – DON’T CHANGE ANYTHING ELSE.
And if we refer to the exposure chart given towards the top of the page we will see that white for the s709 LUT is 77%. So now let’s set Zebra 2 to 77% to make 77% easier to find on the waveform. Do remember however that other LUTs may need different levels, 77% is just for s709, 709(800) would require Zebra 2 to be set to 89%.
SET ZEBRA 2 TO 77% FOR s709
Now with the LUT ON for the SDI/HDMI we should see the brightness of the white card line up with the upper yellow line that represents Zebra 2 and 77%.
As you can see from the above example when the Base ISO and Exposure Index are matched, in this case the base ISO is 800 and the EI is 800, when the LUT for the SDI/HDMI is OFF and the white card is at 61% on the waveform the S-Log3 is correctly exposed. Then when the s709 LUT is ON for the SDI/HDMI the white card will be at 77%. We are correctly exposed. By having Zebra 1 set at 61% (for S-Log3) and Zebra 2 set for the white level for for your chosen LUT we can check either simply by turning the HDMI/SDI LUT ON or OFF.
USING THE 709(800) LUT INSTEAD
If you want a more contrasty looking image in the viewfinder and similar brightness levels to other video cameras – for example skin tones around 70% you might prefer to use the 709(800) LUT. When using the 709(800) LUT to measure a white card you should set Zebra 2 to 89%. It’s also worth noting that with the 709(800) LUT, if you wish, you could just leave the zebras at their default settings with Zebra 1 at 70% where just like a conventional Rec-709 video camera they will appear over brighter skin tones when viewing via the LUT.
CHANGING THE EXPOSURE INDEX TO OFFSET THE LOG EXPOSURE.
Sometimes it can be desirable to expose the S-Log3 a little brighter. For example when shooting scenes with a low average brightness level or scenes with large areas of shadows. The FX6 has very low noise levels at 800 ISO base. So, for most scenes with high average brightness levels there is not normally any need to expose the log any brighter than the normal Sony recommended levels. There is however a bit more noise at 12,800 ISO base. As a result it can be beneficial to expose the S-Log3 a bit brighter than the base level when using 12,800 ISO base to help keep the noise in the final image low.
CineEI Allows Accurate Control Over Exposure.
The CineEI mode makes this very easy to do in a very controlled manner. Keeping the amount of over exposure constant helps speed up the grading process as all your material can be graded in exactly the same way.
Over exposing or underexposing Log does not change the captured dynamic range, it will always be the same. However exposing log brighter will reduce the highlight range while at the same time increasing the shadow range. A brighter exposure will result in less noise after grading.
Exposing log darker will increase the highlight range but decrease the shadow range. A darker exposure will result in more noise after grading. Because under exposed log can become very noisy, very quickly I do not recommend under exposing log, because of this I strongly advise against ever using an EI that is higher than the base ISO as this will result in under exposed log.
CHANGING THE EI ONLY CHANGES THE LUT.
When you change the Exposure Index the only thing that actually changes is the brightness of the LUT. So for EI to work you must be monitoring via a LUT.
Below is what happens to the image in the viewfinder when you have a LUT enabled (s709 in this case) and you lower the EI from 800 EI down to 200 EI in 1 stop steps and make no changes to the exposure.
Changing the EI does not change the exposure in any way, the only thing changing is the brightness of the LUT. The recording levels have not yet changed in any way.
BUT NOW WE CHANGE THE EXPOSURE
At a lower than than base EI the image in the viewfinder is dark and the white card no longer reaches the correct exposure for the LUT, because we see this dark image and the level of the white card too low we now adjust the exposure to compensate.
In this example I simply opened the aperture by 2 stops from f8 to f4 to match the 2 stop change in the LUT brightness. Now the image in the viewfinder looks correct again and the white card is meeting the upper yellow line again (77% as set by Zebra 2 level).
BECAUSE THE EXPOSURE IS BRIGHTER THE S-LOG3 IS NOW ALSO BRIGHTER.
Because I have opened the aperture by 2 stops to make the 200 EI LUT exposure look right the S-Log3 recordings will now be 2 stops brighter. If I turn off the LUT for the SDI/HDMI we can see that the S-Log3 that will be recorded is now 2 stops brighter, the S-log3 white card level becomes 79%, so it appears slightly above the 77% Zebra 1 line.
By making the LUT darker by 2 stops, then adjusting the exposure upwards 2 stops to return the LUT to the original brightness we have made our recordings 2 stops brighter. This is how you use CineEI to alter the brightness of your recordings. A lower EI leads to a darker LUT and because the LUT looks dark we increase the exposure making the recording brighter. A brighter recording will have less noise than a darker recording.
At Low base ISO (800 ISO) the FX6 is a low noise camera, so there is no need to routinely over expose the log as there is with more noisy cameras like the FS5 or FS7. So I normally shoot at 800 EI. When using the high base ISO or 12,800 ISO there is a bit more noise and when using high base I will typically set the EI to 6400 EI as the 1 stop brighter recordings that this will result in helps compensate for the increased recording noise.
DYNAMIC RANGE and HIGHLIGHT/SHADOW RANGE:
When you shoot with a low EI the LUT will be dark and as a result f the dark viewfinder image you will expose brighter putting more light onto the cameras sensor. This brighter exposure will decrease the amount of noise in the final image and give you a greater shadow range. But at the same time it will decrease the highlight range that can be captured.
If you use a high EI value then the opposite happens. The brighter viewfinder image and higher LUT levels will make you want to expose darker to compensate. The resulting darker S-Log3 recording will have an increased highlight range but it will be considerably more noisy than recordings done at the base EI and will have a reduced shadow range. Generally I try to avoid ever using an EI value higher than the base ISO value. In a low light situation using a high EI value will make the image in the viewfinder brighter but on a small screen you won’t see the noise. I do not recommend using high EI values.
IF YOU DON’T HAVE A WHITE CARD?
In the examples given here I have used a white card to measure and set the exposure. This is accurate and highly repeatable. But there will be times where you may not have a white card. At these times CineEI can still be used either by setting the Zebras to the appropriate skin tone levels for the chosen LUT (see the table towards the beginning) or by carefully “eyeballing” the brightness of the LUT image on the viewfinder screen or a monitor screen – if it looks right, it probably is right. If you are eyeballing it I highly recommend a deep sunshade or other device to exclude as much light as possible from the viewfinder. With a properly shaded viewfinder or monitor it is perfectly possible to shoot just by eyeballing the LUT’d image on the screen. As an exposure that is a little too dark is often going to cause more problems than an exposure that is a little too bright, if “eyeballing” the image I suggest using an EI that is 1 stop lower than the base EI. So in the case of the FX6 I would use 400 EI for low base ISO and 6400 EI for high base ISO.
CLIP PLAYBACK QUIRKS (YOU MUST ENSURE YOU HAVE UPDATED YOUR CAMERAS FIRMWARE as there was a bug in the initial release firmware that caused the playback EI to be applied back to front).
One great FX6 feature is that when you play back clips in the CineEI mode the camera can apply a LUT to the clip. Simply enable the LUT you want to use as you would when shooting. The FX6 applies then the EI offset that you have assigned to the L/M/H gain/ISO switch.
HOWEVER YOU DO THIS BE AWARE THAT THE L/M/H Gain switch alters the brightness of the clips when played back via a LUT. The only time there is no playback offset is when the switch is set to 800EI. So make sure you understand what EI it is you are looking at when playing back clips in CineEI as if you use the wrong EI your clips may appear over or under exposed.
I hope you found this guide useful. Good luck with your FX6, it is a very capable camera.
Changing the way the camera looks and using LUTs in Custom Mode:
You can also use any user LUTs that you have loaded into the camera to alter the base look when you are shooting in custom mode. For more information on that please watch the video below.