Quite a lot of people like to use S-Log2 or S-Log3 in custom mode. I’m not a fan of this method myself, I prefer to use CineEI, but for some people using S-Log2 or S-Log3 in custom works for them. If you use S-Log2/3 in custom mode then you are working with 709 color space, so if you want to use a LUT in post you need a LUT designed for this combination. So I have created two sets, one set for S-Log2 and one set for S-Log3. The LUT’s include over and under exposure compensation and you can download them here.
NORMAL: Indicates correct Slog2 exposure, middle grey at 32% and white at 59%, for SLog3 use middle grey 41%, white 61%.
1OVER etc indicates that the LUT will compensate for footage one stop over exposed.
If you are exposing the Slog2 so that skin tones are in the 60-70% region you will most likely need to use the 2 or 3OVER LUT’s.
Click on the links below to download the LUT sets. PLEASE DO NOT HOST THESE ELSEWHERE OR DISTRIBUTE THESE ELSEWHERE OR VIA ANY MEANS OTHER THAN A LINK TO THIS PAGE.
Cameras with bayer CMOS sensors can in certain circumstances suffer from an image artefact that appears as a grid pattern across the image. The actual artefact is normally the result of red and blue pixels that are brighter than they should be which gives a magenta type flare effect. However sometimes re-scaling an image containing this artefact can result in what looks like a grid type pattern as some pixels may be dropped or added together during the re scaling and this makes the artefact show up as a grip superimposed over the image.
Grid type artefact.
The cause of this artefact is most likely off-axis light somehow falling on the sensor. This off axis light could come from an internal reflection within the camera or the lens. It’s known that with the F5/F55 and FS7 cameras that a very strong light source that is just out of shot, just above or below the image frame can in some circumstances with some lenses result in this artefact. But this problem can occur with almost any CMOS Bayer camera, it’s not just a Sony problem.
The cure is actually very simple, use a flag or lens hood to prevent off axis light from entering the lens. This is best practice anyway.
So what’s going on, why does it happen?
When white light falls on a bayer sensor it passes through color filters before hitting the pixel that measures the light level. The color filters are slightly above the pixels. For white light the amount of light that passes through each color filter is different. I don’t know the actual ratios of the different colors, it will vary from sensor to sensor, but green is the predominant color with red and blue being considerably lower, I’ve used some made up values to illustrate what is going on, these are not the true values, but should illustrate the point.
In the illustration above when the blue pixel see’s 10%, green see 70% and red 20%, after processing the output would be white. If the light falling on the sensor is on axis, ie coming directly, straight through the lens then everything is fine.
But if somehow the light falls on the sensor off axis at an oblique angle then it is possible that the light that passes through the blue filter may fall on the green pixel, or the light from the green filter may fall on the red pixel etc. So instead of nice white light the sensor pixels would think they are seeing light with an unusually high red and blue component. If you viewed the image pixel for pixel it would have very bright red pixels, bright blue pixels and dark green pixels. When combined together instead of white you would get Pink or Blue. This is the kind of pattern that can result in the grid type artefact seen on many CMOS bayer sensors when there are problems with off axis light.
This is a very rare problem and only occurs in certain circumstances. But when it does occur it can spoil an otherwise good shot. It happens more with full frame lenses than with lenses designed for super 35mm or APSC and wide angles tend to be the biggest offenders as their wide Field of View (FoV) allows light to enter the optical path at acute angles. It’s a problem with DSLR lenses designed for large 4:3 shaped sensors rather than the various wide screen format that we shoot video in today. All that extra light above and below the desired widescreen frame, if it isn’t prevented from entering the lens has to go somewhere. Unfortunately once it enters the cameras optical path it can be reflected off things like the very edge of the optical low pass filter, the ND filters or the face of the sensor itself.
The cure is very simple and should be standard practice anyway. Use a sun shade, matte box or other flag to prevent light from out of the frame entering the lens. This will prevent this problem from happening and it will also reduce flare and maximise contrast. Those expensive matte boxes that we all like to dress up our cameras with really can help when used and adjusted correctly.
I have found that adding a simple mask in front of the lens or using a matte box such as any of the Vocas matte boxes with eyebrows will eliminate the issue. Many matte boxes will have the ability to be fitted with a 16:9 or 2.40:1 mask ( also know as Mattes hence the name Matte Box) ahead of the filter trays. It’s one of the key reason why Matte Boxes were developed.
Note the clamp inside the hood for holding a mask in front of the filters on this Vocas MB216 Matte Box. Not also how the Matte Box’s aperture is 16:9 rather than square to help cut out of frame light.Arri Matte Box with Matte selection.
You should also try to make sure the size of the matte box you use is appropriate to the FOV of the lenses that you are using. An excessively large Matte Box isn’t going to cut as much light as a correctly sized one. I made a number of screw on masks for my lenses by taking a clear glass or UV filter and adding a couple of strips of black electrical tape to the rear of the filter to produce a mask for the top and bottom of the lens. With zoom lenses if you make this mask such that it can’t be seen in the shot at the wide end the mask is effective throughout the entire zoom range.
Many cinema lenses include a mask for 17:9 or a similar wide screen aperture inside the lens.
Here are two sets of LUT’s for use in post production with the PXW-FS7, PMW-F5 and PMW-F55.
These LUT’s are based around the Sony 709(800) LUT and the Sony LC-709TypeA LUT (Arri Alexa look). But in addition to the base LUT designed for when you shoot at the native ISO there are LUTs for when you shoot at a lower or higher EI.
When you shoot at a high or low EI the resulting footage will be either under or over exposed when you add the standard LUT. These LUT’s include compensation for the under or overexposure giving the best possible translation from SGamut3.cine/S-log3 to rec-709 or the Alexa look and result in pleasing skin tones and a nice mid range with minimal additional grading effort.
If you find these LUT’s useful please consider buying me a coffee or beer.
A very useful feature not well documented on the FS7, F5 and F55 cameras (and the F65 too) is the High/Low Key feature.
The High/Low Key function works by changing the brightness range of the image displayed in the viewfinder, this is very useful when shooting in the Cine-EI Mode and using a LUT to help judge your exposure.
My preferred LUT for exposure assessment is the 709(800) LUT. As this LUT is compatible with the gamma curve used in most TV’s and monitors it provides a nice contrasty image with what I would call “normal” brightness levels (middle grey at 42%, white at 90%, skin tones around 60-70%). So if you expose via the 709(800) LUT so that the pictures look right on the screen or in the viewfinder then your S-Log recordings will also be correctly exposed.
But the 709(800) LUT, like most LUT’s cannot show the full 14 stop capture range of the the S-Log recordings. So sometimes you might see an image via the LUT that looks correctly exposed but the highlights might look clipped or blown out as they are beyond the range of what the LUT can show as in the image below where the sky looks blown out. This is where the High/Low Key function comes in to play.
Normal range 709(800) as seen in the viewfinder. Is the sky over exposed or not in the Slog recording? It’s hard to tell.
To access the function you have to assign High/Low Key to one of the cameras assignable buttons. Once assigned to a button on the first press of the button the viewfinder or monitor image will show the High Key parts of the shot. To do this the VF or monitor picture is made darker so that you can “see” into the full highlight capture range. “High Key” will be displayed in the top left hand corner of the viewfinder. As you can see in the image below we can now see that the sky is not blown out, so we know the S-log recording will be OK.
The High Key function darkens the LUT image so we can view the High Key range of the Slog recordings . We can see that the sky is not over exposed so the Slog recording will be not be clipped or over exposed.
The second press of the button shows the Low Key (darker) parts of the scene. This is done by making the image much brighter so you can “see” into the shadows better and the entire under exposure range of what is being recorded is shown. “Low Key” is displayed in the top left of the viewfinder screen.
The Low Key function brightens the LUT image so we can see whats going on in the deepest shadows and dark areas (Low Key areas) of the Slog capture range.
The third press of the button returns the image to the normal range that the LUT can show.
So by using the High / Low Key function you can see the entire range that the camera is capturing, check for over exposure or under exposure issues without having to turn the LUT on or off. This is a really useful function that I recommend you take advantage of when shooting with CineEI and LUT’s. However do remember to make sure you are back to the standard view range when setting your exposure level.
I have created two new sets of film look LUT’s for the FS7, F5 and F55. These LUT’s should be used in conjunction with S-Log3 and SGamut3.cine. They will give you a high contrast film like look that mimics Kodak film stock with slightly blue dark and mid tones and warm skin tones. The are 3D cube LUT’s and the two sets include LUT’s with compensation for under and over exposure.
To use the LUT’s in camera on the PXW-FS7, PMW-F5 or PMW-F55 then the LUT’s need to be placed in the PMWF55_F5 folder on an SD card. The correct folder structure should look like this:
PRIVATE – SONY – PRO – CAMERA – PMWF55_F5
Slog3_cine-film-look-luts
If you find the LUT’s useful please consider buying me a drink, they did take some time to create:
I have just published a major update to my guide to Cine-EI on the PMW-F55 and F5. The guide now goes in to a lot more depth. I have tried to make it easy to understand but it is also quite technical, I have deliberately included the technical background stuff so that hopefully you will understand why Cine-EI and LUT’s work the way they do. I’ve added a whole new section on exposure methods for some of the different LUT’s as well as how to create your own LUT’s.
Please take a look if you use these cameras. Soon I will add a section on post production.
Been playing a lot with HFR recently on my F5. One of the niggles with HFR/S&Q on the PMW-F55 and F5 is that you don’t have LUT’s when shooting HFR. But, in firmware V4 Sony added a new high contrast mode for the viewfinder. I now have this allocated to one of my assignable buttons and it makes a pretty good LUT alternative for shooting in HFR.
I find that when shooting with S-Log3 HFR I can get a pretty good approximation of correct exposure using the VF High Contrast mode and as the image has decent contrast, focus is much easier than when trying to work without any kind of LUT. Sadly this is only available in the viewfinder, but I find that it is much more obvious if your exposure is off when you use the VF High Contrast mode.
The camera automatically turns this mode OFF when you power the camera down, so you must re-enable it when you power cycle the camera. This is probably a good thing as it means you shouldn’t accidentally find it left on next time you power up the camera and forget you had been using it..
Sadly zebras etc either measure the LUT output or the Slog, they are NOT effected by the viewfinder HC mode, so in HFR they will be measuring the SLog.
It’s very easy to check out this function for yourself. In regular, non HFR Cine EI,at the native ISO, turn ON the 709(800) LUT and view the image in the viewfinder making a mental note of what it looks like. Now turn the VF LUT’s OFF and turn on the VF High Contrast mode. You will see that the VF image almost exactly the same in both modes.
So at the native ISO: Cine EI + 709(800) LUT gives the same image in the VF as CineEI NO LUT + VF High Contrast mode.
I recommend that if you haven’t played with this in HFR/S&Q you give it a try. It’s not a true LUT, but it looks just the same as the 709(800) LUT.
It’s very easy to create your own 3D LUT for the Sony PMW-F5 or PMW-F55 using DaVinci Resolve or just about any grading software with LUT export capability. The LUT should be a 17x17x17 or 33x33x33 .cube LUT (this is what Resolve creates by default).
Simply shoot some test Slog2 or Slog3 clips at the native ISO. You must use the same Slog and color space as you will be using in the camera.
Import and grade the clips in Resolve as you wish the final image to look. Then once your happy with your look, right click on the clip in the timeline and “Export LUT”. Resolve will then create a .cube LUT.
Then place the .cube LUT file created by the grading software on an SD card in the PMWF55_F5 folder. You may need to create the following folder structure on the SD card, so first you have a PRIVATE folder, in that there is a SONY folder and so on.
PRIVATE : SONY : PRO : CAMERA : PMWF55_F5
Put the SD card in the camera, then go to the File menu and go to “Monitor 3D LUT” and select “Load SD Card”. The camera will offer you a 1 to 4 destination memory selection, choose 1,2,3 or 4, this is the location where the LUT will be saved. You should then be presented with a list of all the LUT’s on the SD card. Select your chosen LUT to save it from the SD card to the camera.
Once loaded in to the camera when you choose 3D User LUT’s you can select between user LUT memory 1,2,3 or 4. Your LUT will be in the memory you selected when you copied the LUT from the SD card to the camera.
First of all. You can use either, LUT’s or Looks. But there is a quite marked difference in the way they behave, especially if you use EI gain.
At the native ISO there is little to choose between them. But just to confirm my earlier suspicions about the way the 3D LOOK’s behave I ran a quick test.
I found that when you lower the EI gain, below native, the output level of the LOOK lowers, so that depending on the EI, the clipping, peak level and middle grey values are different. For example on my PMW-F5 at 500 EI the LC709TypeA LUT has a peak output (clipping) level of just 90% while at 2000 ISO it’s 98%. This also means that middle grey of the LOOK will shift down slightly as you lower the EI. This means that for consistent exposure at different low EI’s you may need to offset your exposure very slightly. It also means that at Native EI if the waveform shows peak levels at 90% you are not overexposed or clipped, but at low EI’s 90% will mean clipped Slog, so beware of this peak level offset.
When you raise the EI of the LOOKS, the input clipping point of the Look profile changes. For each stop of EI you add the LOOK will clip one stop earlier than the underlying Slog. For example set the LC709TypeA LUT to 8000 ISO (on my PMW-F5) and the LOOK itself hard clips 2 stops before the actual SLog3 clips. So your LOOK will make it appear that your Slog is clipped up to 2 stops before it actually is and the dynamic range and contrast range of the LOOK varies depending on the EI, so again beware.
So, the Looks may give the impression that the Slog is clipped if you use a high ISO and will give the impression that you are not using your full available range at a low ISO. I suspect this is a limitation of 3D LUT tables which only work over a fixed 0 to1 input and output range.
What about the 1D LUT’s? Well the LUT’s don’t cover the full range of the Slog curves so you will never see all of your dynamic range at once. However I feel their behaviour at low and high EI’s is a little bit more intuitive than the level shifts and early clipping of the LOOKs.
The 1D LUT’s will always go to 109%. So there are no middle grey shifts for the LUT, no need to compensate at any ISO. In addition if you see any clipping below 109% then it means your SLog is clipping, for example if you set the camera to 500 ISO (on an F5), when you see the 709(800) LUT clipping at 105% it’s because the Slog is also clipping.
At High ISO’s you won’t see the top end of the SLog’s exposure range anyway because the LUT’s range is less than Slog’s range, but the LUT itself does not clip, instead highlights just go up above 109% and this is in my opinion more intuitive behaviour than the clipped LOOK’s that don’t ever quite reach 100% and clip at lower than 100% even when the Slog itself isn’t clipped.
At the end of the day use the ones that work best for you, just be aware of the limitations of both and that the LUT’s and LOOKs behave very differently. I suggest you test and try both before making any firm decisions.
Personally I prefer to use the 709(800) LUT for exposure as the restricted range matches that of most consumer TV’s etc so I feel this gives me a better idea of how the image may end up looking on a consumers TV. Also I find my Slog exposure more accurate as the LUT’s restricted range means you are more likely to expose within finer limits. In addition as noted above I fell the LUT’s behaviour is more predictable and intuitive at high and low EI’s than the LOOK’s.
In addition the higher contrast makes focus easier. I will often switch in and out of the LUT to look at how the Log is coping with any over exposure. This is my personal preference, but I do also use other LUT’s and Looks in particular the 709TypeA from time to time.
There is an ongoing and much heated debate on another forum about the practicalities of using the LUT’s or Looks built in to the PMW-F5 and PMW-F55 for setting the correct exposure of your SLog or Raw footage. In response to this I put together a very rough video demonstrating how this actually works.
Before watching the video, do please understand the following notes:
Correct exposure is normally determined by the level at which middle grey is recorded. This is true of both video and film production. Light meters are calibrated using middle grey. Expose with a light meter and you will find middle grey at the levels indicated below.
Different gamma curves may use different middle grey levels depending on the contrast required and the dynamic range of the gamma curve. Generally speaking, the greater the dynamic range, the lower middle grey must be set in order to leave room above middle grey for the extra dynamic range. This means that the relationship between middle grey and white will be different from curve to curve. Don’t always expect white to be some fixed value above middle grey. Some of the Sony looks for example LC709TypeA are very low contrast and while middle grey still sits at around 42% (The ITU standard for Rec-709 is 41.7%), because it is a low contrast, high dynamic range curve white is at a lower level, around 70%. The Hypergamma LUT grey points are given by the “G40″ or G33” number – G40 meaning middle grey at 40%.
When you take Slog or raw in to post production it is expected that the middle grey of the recordings will be at the correct nominal level (see chart below). If it is not, when you apply a post production Slog or raw LUT then the footage may appear incorrectly exposed. If you try to bring Slog or raw into an ACES workflow then ACES expects middle grey to be at the correct values. So it is important that your Slog or raw is exposed correctly if you want it to work as expected in post.
Correct exposure levels for Sony’s Slog.
Having said all of the above… If you are using CineEI and lowering or raising the EI gain from the native ISO then your Slog or raw will be exposed brighter or darker than the levels above. But I must assume that this is what you want as you are probably looking to adjust the levels in post to reduce noise or cope with an over exposure issue. You may need to use a correction LUT to bring your Slog levels back to the nominal correct levels prior to adding a post production LUT.
Anyway, here’s the video.
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