Something I find useful to consider is that “Exposure” is the amount of light that you put onto the sensor or film stock in your camera. It isn’t brightness, it is how much light. If you think about it, if you use a light meter to find you exposure settings, the light meter has no idea how bright the pictures will be, all it does is give you the shutter and aperture values needed to put the correct amount of light onto the sensor or film stock.
How Cine EI Works.
Next we need to think about how Cine EI works. You have to remember that when shooting using Cine EI the only thing that changes when you change the EI value is the brightness of the LUT and it is also worth considering that different LUTs may be completely different brightness. There is no change to the sensitivity of the sensor and no direct change to the brightness of what is recorded. To change the brightness of what is recorded YOU must change the aperture, shutter speed or ND etc. Normally you would monitor your images via a LUT and then you must adjust the exposure so the image on the viewfinder looks correct at the new Exposure Index, or use the waveform to measure the LUT and use this to set the exposure for the new EI. And by changing the exposure you are adding an exposure offset putting more (or less) light on to the sensor than would be normal at the base EI.
AE In Cine EI.
If you wish to use auto exposure in the Cine EI mode then you need to understand that the camera’s auto exposure system measures what is being recorded. It does not measure the LUT levels. The auto exposure system is unaware of your desire to expose the sensor more or less brightly than normal and will always base the exposure on the base ISO, not the Exposure Index. As a result if you are using AE and you go from 800 EI to 400 EI the image seen via the internal LUT will get darker by one stop, the AE will NOT compensate for the lower EI. If you were to manually brighten the exposure by one stop the cameras exposure meter will think you are now over exposed – because you are!
The only way around this is to add an offset to the AE system to account for the offset added by the different Exposure Index. For example if you want to shoot at 400EI (The LUT becoming 1 stop DARKER) then you would need to add a +1.0 stop offset to the cameras AE settings to offset the exposure 1 stop brighter. Each time you halve the EI you should add an extra +1 stop of offset. Each time you double the EI you should include an extra -1 stop offset.
There are a couple of ways to do this but the quickest is to use the Quick Menu function that is by default assigned to button 5 on the hand grip or button 8 on the handle. Press the direct menu button and then use the thumbstick to go the AE+0 indication just above the shutter speed indicator and add your offset.
Or you can long press the menu button to go into the cameras main menu then go to the – Shooting – Auto Exposure page and add your offset to the Level setting.
I don’t recommend the use of Auto Exposure in Cine EI. For a start AE uses the average brightness of the scene to set the exposure level, often this isn’t appropriate for Log. When shooting with log generally you want to ensure that it is your mid range is exposed at the right level and you don’t want bright highlights to result in an under exposed mid range. Additionally if the exposure changes mid shot this can make grading very difficult. If you do use auto exposure in Cine EI, then as well as adding any necessary offsets I also recommend slowing down the responsiveness of the AE using the “Speed” setting in the Auto Exposure menu. Using a value such as -60 will slow down the rate at which the AE will change the exposure which helps avoid rapid auto exposure changes for momentary light changes within the scene.
It is really important to remember that Exposure is NOT brightness. Exposure is how much light you put on the sensor. A light meter doesn’t know how bright you want your pictures to be. All it knows is the correct amount of light to put on to the sensor for the “correct” exposure. If using an external light meter provided you put the right values into your light meter it will give you the correct exposure settings, even though it has no idea how bright your pictures will be and the camera’s internal exposure meter acts in a similar way, so offsets are needed to match each EI you use.
This came up in one of the user groups today and I thought I would repeat the information here.
One issue when using the Atomos Ninja V+ rather than an older Atomos Shogun or Inferno is that the Ninja V+ doesn’t have an internal S-Log2 option. This seems to cause some users a bit of confusion as most are aware that for the best results the FS5 MUST to be set to PP7 and S-Log2 as this is the only setting that fully optimises the sensor setup.
When you shoot raw, you are recording linear raw, the recordings don’t actually have any gamma as such and they are not S-log2 or S-Log3, they are raw. The S-Log2 setting in the FS5 just ensures the camera is optimised correctly. If you use the S-Log3 settings, what you record is exactly the same – linear raw, just with more noise because the camera isn’t as well optimised.
Any monitor or post production S-Log2 or S-Log3 settings are simply selecting the intermediate gamma that the raw will be converted to for convenience. So when the Ninja V+ states S-Log3 this is simply what the Ninja converts the raw to, before applying any LUT’s. It doesn’t matter that this is not S-Log2 because you didn’t record S-Log2, you recorded linear raw. This is simply what the Ninja V+ will use internally when processing the raw.
You have to convert the raw to some sort of gamma so that you can add LUT’s to it and as S-Log3 LUT’s are commonly available S-Log3 is a reasonable choice. With earlier recorders you had the option to choose S-Log2 so that when viewing the native S-Log2 output from the camera, what you saw on the monitors screen looked similar to what you saw on the FS5’s LCD screen when the FS5 was set to S-Log2. But S-Log2 is no longer included in the latest monitors, so now you only have the option to use S-Log3. But from an image quality point of view this monitor setting makes no difference and has no effect on what is recorded (the FS5 should still be set to PP7 and S-Log2).
In post production in the past, for consistency it would have been normal to decode the raw to S-Log2 so that everything match throughout your production pipeline from camera to post. But again, it doesn’t really matter if you now decode the raw to S-Log3 instead if you wish. There will be no significant quality difference and there is a wider range of S-Log3 LUT’s to choose from.
If the footage is too noisy then it is under exposed, it’s the only reason why the footage will be excessively noisy. It is true that raw bypasses the majority of the cameras internal noise reduction processes, but this only makes a small difference to the overall noise levels.
Even with the latest Ninja V+ what is recorded when outputting raw from the FS5 is 12 bit linear raw.
12 bit Linear raw is a somewhat restricted format. 12 bits is not a lot of code values to record a high dynamic range linear signal. This is why most cameras use log recording for wide dynamic ranges, log is much more efficient and distributes the available recording data in a way very sympathetic to the way human vision works.
In practice what this means is that the 12 bit linear raw has LOTS of data and image information in the upper mid range and the very brightest highlights. But relatively very little picture information in the lower mid range and shadows. So if it is even the slightest bit under exposed the image will degrade very quickly as for each stop yu go down in brightness you halve the amount of image information you have.
In an underexposed image the noise will be very coarse in appearance and the image will be difficult to grade. You really do need to expose the raw nice and bright and because of the way the data is distributed, the brighter you can get away with the better. Never be afraid of exposing linear raw “just a little bit brighter”. It is unlikely to severely bite you if you are over exposed but highly likely to bite you if it is even a fraction under.
The 12 bit linear raw from the FS5 is not going to be good in low light or when shooting scenes with large shadow areas unless you can expose bright so that you are bring your levels down in post. If you have to bring any levels up in post the image will not be good.
Raw is not a magic bullet that makes everything look great. Just as with S-Log it must be exposed carefully and 12 bit linear raw is particularly unforgiving – but when exposed well it is much better than the internal 8 bit log recordings of the FS5 and can be a fantastic format to work with, especially given the low cost of an FS5.
I recommend going back to basics and using a white card to measure the exposure. If monitoring the raw via S-Log3 the white card needs to be exposed around 70%. If using a light meter with the FS5 set the light meter to 640 ISO.
If you do want to use a LUT on the Ninja to judge your exposure use a LUT with a -1.5 stop offset. The darker LUT will encourage you to expose the raw brighter and you will find the footage much easier to grade. But it should also be considered that it is also quite normal to add a small amount of selective noise reduction in post production when shooting raw.
This is a common problem and something people often complain about. It may be that the LCD screen of their camera and the brightness of the image on their monitor don’t ever seem to quite match. Or after the shoot and once in the grading suite the pictures look brighter or darker than they did at the time of shooting.
A little bit of background info: Most of the small LCD screens used on video cameras are SDR Rec-709 devices. If you were to calibrate the screen correctly the brightness of white on the screen would be 100 Nits. It’s also important to note that this level is the level that is also used for monitors that are designed to be viewed in dimly lit rooms such as edit or grading suites as well as TV’s at home.
The issue with uncovered LCD screens and monitors is your perception of brightness changes according to the ambient viewing light levels. Indoors in a dark room the image on it will appear to be quite bright. Outside on a Sunny day it will appear to be much darker. It’s why all high end viewfinders have enclosed eyepieces, not just to help you focus on a small screen but also because that way you are always viewing the screen under the very same always dark viewing conditions. It’s why a video village on a film set will be in a dark tent. This allows you to then calibrate the viewfinder with white at the correct 100 NIT level and then when viewed in a dark environment your images will look correct.
If you are trying to use an unshaded LCD screen on a bright sunny day you may find you end up over exposing as you compensate for the brighter viewing conditions. Or if you also have an extra monitor that is either brighter or darker you may become confused as to which is the right one to base your exposure assessments on. Pick the wrong one and your exposure may be off. My recommendation is to get a loupe for the LCD, then your exposure assessment will be much more consistent as you will then always be viewing the screen under the same near ideal conditions.
It’s also been suggested that perhaps the camera and monitor manufacturers should make more small, properly calibrated monitors. But I think a lot of people would be very disappointed with a proper calibrated but uncovered display where white would be 100 NITs as it would be too dim for most outside shoots. Great indoors in a dim room such as an edit or grading suite but unusably dim outside on a sunny day. Most smaller camera monitors are uncalibrated and place white 3 or 4 times brighter at 300 NIT’s or so to make them more easily viewable outside. But because there is no standard for this there can be great variation between different monitors making it hard to understand which one to trust depending on the ambient light levels.
A question poped up today asking about how to expose S-Cinetone when shooting green screen. The answer is really quite simple – no differently to how you would expose S-Cinetone anywhere else. But, having said that it is important to understand that S-Cinetone is a bit different to normal Rec-709 and this needs to be considered when shooting for chroma key or green screen.
S-Cinetone’s highlight roll off and shoulder starts much lower than most “normal” rec-709 curves. From around 73% the gamma curve changes and starts to compress the levels and reduce contrast. In the shdows there is a variable toe that increases contrast at lower brightness levels. The nominal “normal” brightness levels are also lower, all part of the contemporary film like look S-Cinetone is designed to give. A 90% reflectivity reference white card would be exposed at approx 83% instead of the more normal 90% (if you were using a light meter you should end up with a 90% white card at 83IRE). A white piece of paper will be a bit brighter than this as printer and copier paper etc is designed to look as bright as possible, typically printer paper comes out around 3 to 5% brighter than a proper white card.
The lower start to the highlight roll-off means that if you place skintones around 70% the brighter parts of a face will be affected by the rolloff and this will make them flatter. Expose skin tones at 60% and the face will be more contrasty and in my opinion look better. Although darker this would still be well with the “normal” exposure range for S-Cinetone so you will not have excessive noise and it will still key well.
S-Cinetone would be considered correctly exposed when a 90% white card is exposed between 78% and 88%. This is quite a wide window and is due to the way S-Cinetone is designed to give differening contrast levels simply by exposing a touch brighter or darker. The variable toe and shoulder mean that exposing brighter will make the image flatter and exposing darker more contrasty. Exposing as you would with normal Rec-709 levels with a white card at 90% will place skintones rather higher than “normal” and they will appear very flat. So either expose so a white card falls in the 78-88% window or use a calibrated monitor to observe how the skin tone look and be careful not to overexpose them.
Your greenscreen should be between 40IRE and 60IRE for a good clean key, I normally aim for 50IRE with S-Cinetone, but provided you don’t go below 40IRE or above 60IRE you should be good.
Lots of people have been asking about how to expose S-Cinetone, whether with the FX9, FX6, A7SIII or the FX3.
The short answers is: So that it looks nice!
S-Cinetone has a variable toe and knee. So exposing it brighter results in not only a brighter image but also an image with flatter skin tones and less shadow contrast, overall looking more video like.
Exposing a little bit darker results in a more contrasty film like image. Faces and skin tones have more texture. There is no one optimum exposure level. A white card could be anywhere between 78% and 88% depending on the look you want. Typical skin tones will vary from between anywhere between 55% and 75%.
Personally I like the way S-Cinetone looks when it’s exposed with Skin tones at around 63% and white at around 81%.
See the video I on S-Cinetone on the FX9 for more details as it all applies equally to the FX9 and FX6 as well as the A7SIII and FX3. The only small difference is that the base ISO’s are a little different between each camera.
In the course of my tests with the FX3 and comparing it with the FX6 and FX9 I discovered a strange anomaly with the FX3 and A7SIII ISO ratings when compared to the FX6 and FX9.
The FX3’s default picture profile is PP11 and S-Cinetone. If you have an FX6 or FX9 these cameras also default to S-Cinetone in SDR mode. In the FX6 and FX9 the base ISO for S-Cinetone is 320 ISO. Therefore you would assume that if you also set the A7SIII or the FX3 to 320 ISO and expose all the cameras the same, same aperture, shutter etc that the exposures would match.
BUT THE EXPOSURES DON’T MATCH!!
The FX3 and the A7SIIII are just over 1 stop brighter than the FX6 and FX9 when all the exposure settings are matched. I tested all the cameras with the same lens to ensure this wasn’t a lens issue, but it isn’t the lens.
I then went on to test other gamma/picture profile settings and I found a just over 1 stop difference between the FX3 and my FX6/FX9 in any similar combination EXCEPT S-LOG3!
When using Picture Profile 2 on the FX3 which is uses Sony’s “Still” gamma and then using the “Still” Profile on the FX6 there is a difference of around 1 stop. If I set the FX3 to PP3 (ITU-709) and the FX6 to ITU-709 then the difference is again around 1 stop, in every case the FX3 is brighter except when you select S-Log3 where the FX3 and the FX6/FX9 match almost perfectly!
I find this very strange. They should not be different. My light meter suggests to me that the FX6/FX9 are correct.
Comparing to my light meter I believe the FX6/FX9 ratings to be correct and the FX3 to be between 1 and 1.3 stops brighter than it should be when using gammas that are not S-Log3. What I really don’t understand is why the FX3/A7SIII match the FX6/FX9 when using S-Log3 but do not match when using the other profiles, normally I would expect to see a consistent offset. This further makes leads me to be sure this is not a problem with my light meter, but something else.
I would love to hear from anyone else that’s able to take a look at the ISO ratings of the A7SIII and compare it with an FX6 or FX9.
The bottom line is – DON’T EXPECT TO PUT THE SAME EXPOSURE SETTINGS INTO BOTH AN FX3 AND AN FX6/FX9 AND GET THE SAME RESULTS, because you won’t, unless you are using S-Log3, then they match.
Also in the clip metadata I found that 0dB for S-Cinetone is 100 ISO, and whether this is a coincidence or not, if I set the FX3 to 100 ISO and the FX6 to 320 ISO and then match shutter speed and aperture then the exposures are very close.
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/
While I had the light meter and exposure test chart out for the FX6 I decided to do the same exposure level confirmation test for the FX9. No nasty surprises, the FX9’s ISO ratings certainly appear to be correct. Again using a DSC Labs exposure reference chart with 18% middle grey and 90% white plus my trusty Sekonic I tested the FX9 at both 800 ISO and 4000 ISO and my light meter and the camera were in good agreement. At 800 ISO the light meter was saying f4.01 while the camera was at f4, I suspect this tiny difference is probably down to transmission losses in the lens.
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 either S-Log3 or raw with the best possible dynamic range.
It also 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 an approximation of how your footage will look after it’s been graded as well as to assist you in getting the exposure 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.
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, but in addition to the built in LUTs you can load your own “user LUTs” into the camera as what the FX6 calls “Base Looks” making this a very flexible and capable system. 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 formated in card slot 2 of the FX6. The LUT’s should be 17x or preferably 33x cube LUT’s 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.
ENABLE A LUT.
To take full advantage of the Cine EI mode the next step is to enable a LUT for the viewfinder and also optionally for the HDMI and SDI outputs.
The default LUT 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 LUTs and Base Looks. Each LUT/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 LUT that you chose to use needs to be exposed at.
Another LUT that the FX6 includes is Sony’s 709(800) LUT. This LUT is more closely aligned with the levels used in normal TV productions, so it looks very 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) LUTs 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 LUT’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 OK, but it isn’t particularly accurate. My prefered 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.
If you are not familiar with a waveform display it 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 of the video image. The thin 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 to 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.
MEASURING THE EXPOSURE.
The waveform display measures the signal that is on the HDMI and the SDI output. So once you have turned on the LUT for the HDMI/SDI it is the levels of the LUT that is being measured. What the waveform is measuring is indicated just above the waveform display.
To make it easier to understand how CineEI works and to show you how I like to have my FX6 setup, I find it easier to start off 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 equal to the Recording or Base ISO then we can establish the correct exposure for the S-Log3 using a white card or white piece of paper and then also check the exposure of the LUT.
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:
When using the CineEI mode you can change the EI 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.
I do not set an Exposure Index higher than the base recording ISO. The reason for this is that 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 that 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 correct exposure for the LUT and the correct, or base exposure for the S-Log3. Expose the LUT corrrectly 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 above we can see that the correct S-Log3 exposure for 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.
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 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 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.
TURN ON THE LUT.
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, 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 and the white card is 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 higher average brightness levels there is no need to expose the log brighter. But there is a bit more noise at 12,800 ISO base. As a result it can be beneficial to expose the S-Log3 a bit brighter when using 12,800 ISO base.
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.
As we have not changed 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
Because the image in the viewfinder is now dark and the white card no longer reaches the correct exposure for the LUT, we now adjust the exposure. 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 is much brighter 2 stops brighter like this, the S-log3 white card level becomes 79%, so it appears slightly above the 77% Zebra 1 line.
Buy 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.
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.
In the examples given here I have used a white card to 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 – 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.
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.
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.