Tag Archives: LUT

Why do we strive to mimic film? What is the film look anyway?

 

Please don’t take this post the wrong way. I DO understand why some people like to try and emulate film. I understand that film has a “look”. I also understand that for many people that look is the holy grail of film production. I’m simply looking at why we do this and am throwing the big question out there which is “is it the right thing to do”? I welcome your comments on this subject as it’s an interesting one worthy of discussion.

In recent years with the explosion of large sensor cameras with great dynamic range it has become a very common practice to take the images these cameras capture and apply a grade or LUT that mimics the look of many of todays major movies. This is often simply referred to as the “film look”.

This look seems to be becoming more and more extreme as creators attempt to make their film more film like than the one before, leading to a situation where the look becomes very distinct as opposed to just a trait of the capture medium. A common technique is the “teal and orange” look where the overall image is tinted teal and then skin tones and other similar tones are made slightly orange. This is done to create colour contrast between the faces of the cast and the background as teal and orange are on opposite sites of the colour wheel.

Another variation of the “film look” is the flat look. I don’t really know where this look came from as it’s not really very film like at all. It probably comes from shooting with a log gamma curve, which results in a flat, washed out looking image when viewed on a conventional monitor. Then because this look is “cool” because shooting on log is “cool” much of the flatness is left in the image in the grade because it looks different to regular TV ( or it may simply be that it’s easier to create a flat look than a good looking high contrast look). Later in the article I have a nice comparison of these two types of “film look”.

Not Like TV!

Not looking like TV or Video may be one of the biggest drivers for the “film look”. We watch TV day in, day out. Well produced TV will have accurate colours, natural contrast (over a limited range at least) and if the TV is set up correctly should be pretty true to life. Of course there are exceptions to this like many daytime TV or game shows where the saturation and brightness is cranked up to make the programmes vibrant and vivid.  But the aim of most TV shows is to look true to life. Perhaps this is one of the drivers to make films look different, so that they are not true to life, more like a slightly abstract painting or other work of art. Colour and contrast can help setup different moods, dull and grey for sadness, bright and colourful for happy scenes etc, but this should be separate from the overall look applied to a film.

Another aspect of the TV look comes from the fact that most TV viewing takes place in a normal room where light levels are not controlled. As a result bright pictures are normally needed, especially for daytime TV shows.

But What Does Film Look Like?

But what does film look like? As some of you will know I travel a lot and spend a lot of time on airplanes. I like to watch a film or 2 on longer flights and recently I’ve been watching some older films that were shot on film and probably didn’t have any of the grading or other extensive manipulation processes that most modern movies go through.

Lets look at a few frames from some of those movies, shot on film and see what they look like.

Lawrence-of-Arabia-01-1024x576 Why do we strive to mimic film? What is the film look anyway?
Lawrence of Arabia.

The all time classic Lawrence of Arabia. This film is surprisingly colourful. Red, blues, yellows are all well saturated. The film is high contrast. That is, it has very dark blacks, not crushed, but deep and full of subtle textures. Skin tones  are around 55 IRE and perhaps very slightly skewed towards brown/red, but then the cast are all rather sun tanned. But I wouldn’t call the skin tones orange. Diffuse whites typically around 80 IRE and they are white, not tinted or coloured.

braveheart1-1024x576 Why do we strive to mimic film? What is the film look anyway?
Braveheart.

When I watched Braveheart, one of the things that stood out to me was how green the foliage and grass was. The strong greens really stood out in this movie compared to more modern films. Overall it’s quite dark, skin tones are often around 45 IRE and rarely more than 55 IRE, very slightly warm/brown looking, but not orange. Again it’s well saturated and high contrast with deep blacks. Overall most scenes have a quite low peak and average brightness level. It’s quite hard to watch this film in a bright room on a conventional TV, but it looks fantastic in a darkened room.

Indy_cuts_bridge Why do we strive to mimic film? What is the film look anyway?
Raiders Of The Lost Ark

Raiders of the Lost Ark does show some of the attributes often used for the modern film look. Skin tones are warm and have a slight orange tint and overall the movie is very warm looking. A lot of the sets use warm colours with browns and reds being prominent. Colours are well saturated. Again we have high contrast with deep blacks and those much lower than TV skin tones, typically 50-55IRE in Raiders. Look at the foliage and plants though, they are close to what you might call TV greens, ie realistic shades of green.

A key thing I noticed in all of these (and other) older movies is that overall the images are darker than we would use for daytime TV. Skin tones in movies seem to sit around 55IRE. Compare that to the typical use of 70% zebras for faces on TV. Also whites are generally lower, often diffuse white sitting at around 75-80%. One important consideration is that films are designed to be shown in dark cinema theatres where  white at 75% looks pretty bright. Compare that to watching TV in a bright living room where to make white look bright you need it as bright as you can get. Having diffuse whites that bit lower in the display range leaves a little more room to separate highlights from whites giving the impression of a greater dynamic range. It also brings the mid range down a bit so the shadows also look darker without having to crush them.

Side Note: When using Sony’s Hypergammas and Cingeammas they are supposed to be exposed so that white is around 70-75% with skin tones around 55-60%. If used like this with a sutable colour matrix such as “cinema” they can look quite film like.

If we look at some recent movies the look can be very different.

the_revenant Why do we strive to mimic film? What is the film look anyway?
The Revenant

The Revenant is a gritty film and it has a gritty look. But compare it to Braveheart and it’s very different. We have the same much lower skin tone and diffuse white levels, but where has the green gone? and the sky is very pale.  The sky and trees are all tinted slightly towards teal and de-saturated. Overall there is only a very small colour range in the movie. Nothing like the 70mm film of Laurence of Arabia or the 35mm film of Braveheart.

deadmen-1024x576 Why do we strive to mimic film? What is the film look anyway?
Dead Men Tell No Tales.

In the latest instalment of the Pirates of the Caribbean franchise the images are very “brown”. Notice how even the whites of the ladies dresses or soldiers uniforms are slightly brown. The sky is slightly grey (I’m sure the sky was much bluer than this). The palm tree fronds look browner than green and Jack Sparrow looks like he’s been using too much fake tan as his face is border line orange (and almost always also quite dark).

wonder_woman_still_6 Why do we strive to mimic film? What is the film look anyway?
Wonder Woman.

Wonder woman is another very brown movie. In this frame we can see that the sky is quite brown. Meanwhile the grass is pushed towards teal and de-saturated, it certainly isn’t the colour of real grass.  Overall colours are subdued with the exception of skin tones.

These are fairly typical of most modern movies. Colours generally quite subdued, especially greens and blues. The sky is rarely a vibrant blue, grass is rarely a grassy green. Skin tones tend to be very slightly orange and around 50-60IRE. Blacks are almost always deep and the images contrasty. Whites are rarely actually white, they tend to be tinted either slightly brown or slightly teal. Steel blues and warm browns are favoured hues. These are very different looking images to the movies shot on film that didn’t go through extensive post production manipulation.

So the film look, isn’t really about making it look like it was shot on film, it’s a stylised look that has become stronger and stronger in recent years with most movies having elements of this look. So in creating the “film look” we are not really mimicking film, but copying a now almost standard colour grading recipe that has some film style traits.

BUT IS IT A GOOD THING?

In most cases these are not unpleasant looks and for some productions the look can add to the film, although sometimes it can be taken to noticeable and objectionable extremes. However we do now have cameras that can capture huge colour ranges. We also have the display technologies to show these enormous colour ranges. Yet we often choose to deliberately limit what we use and very often distort the colours in our quest for the “film look”.

HDR TV’s with Rec2020 colour can show both a greater dynamic range and a greater colour range than we have ever seen before. Yet we are not making use of this range, in particular the colour range except in some special cases like some TV commercials as well as high end wild life films such as Planet Earth II.

This TV commercial for TUI has some wonderful vibrant colours that are not restricted to just browns and teal yet it looks very film like. It does have an overall warm tint, but the other colours are allowed to punch through. It feels like the big budget production that it clearly was without having to resort to  the modern defacto  restrictive film look colour palette. Why can’t feature films look like this? Why do they need to be dull with a limited colour range? Why do we strive to deliberately restrict our colour pallet in the name of fashion?

What’s even more interesting is what was done for the behind the scenes film for the TUI advert…..

The producers of the BTS film decided to go with an extremely flat, washed out look, another form of modern “film look” that really couldn’t be further from film. When an typical viewer watches this do they get it in the same way as we that work in the industry do?  Do they understand the significance of the washed out, flat, low contrast pictures or do they just see weird looking milky pictures that lack colour with odd skin tones? The BTS film just looks wrong to me. It looks like it was shot with log and not graded.  Personally, I don’t think it looks cool or stylish, it just looks wrong and cheap compared to the lush imagery in the actual advert (perhaps that was the intention).

I often see people looking for a film look LUT. Often they want to mimic a particular film. That’s fine, it’s up to them. But if everyone starts to home in on one particular look or style then the films we watch will all look the same. That’s not what I want. I want lush rich colours where appropriate. Then I might want to see a subdued look in a period piece or a vivid look for a 70’s film. Within the same movie colour can be used to differentiate between different parts of the story. Take Woody Allen’s Cafe Society, shot by Vittorio Storaro for example. The New York scenes are grey and moody while the scenes in LA that portray a fresh start are vibrant and vivid. This is I believe important, to use colour and contrast to help tell the story.

Our modern cameras give us an amazing palette to work with. We have the tools such as DaVinci Resolve to manipulate those colours with relative ease. I believe we should be more adventurous with our use of colour. Reducing exposure levels a little compared to the nominal TV and video – skin tones at 70% – diffuse whites at 85-90%, helps replicate the film look and also leaves a bit more space in the highlight range to separate highlights from whites which really helps give the impression of a more contrasty image. Blacks should be black, not washed out and they shouldn’t be crushed either.

Above all else learn to create different styles. Don’t be afraid of using colour to tell your story and remember that real film isn’t just brown and teal, it’s actually quite colourful. Great artists tend to stand out when their works are different, not when they are the same as everyone else.

 

Advertisements

Guide to Cine EI – Still Current.

Just a reminder that my guide to shooting with Cine EI for the PMW-F5 and F55 cameras is still just as valid today as it was when I wrote it back in 2013. There have been a few tweaks to the cameras menu here and there, but the principles and basic operation have not changed.

So if you are new to Cine-EI please take a look at the guide. It takes you through how to shoot with Cine EI, which LUT’s to use and how to expose them.

Cine-EI Mode when recording S-Log2/3 and raw on the F5 and F55.

Want to shoot direct to HDR with the PXW-FS7, PMW-F5 and F55?

Sony will be releasing an update for the firmware in the Sony PXW-FS5 in the next few days. This update amongst other things will allow users of the FS5 to shoot to HDR directly using the Hybrid Log Gamma HDR gamma curve and Rec2020 color. By doing this you  eliminate the need to grade your footage and could plug the camera directly in to a compatible HDR TV (the TV must support HLG) and see an HDR image directly on the screen.

But what about FS7 and F5/F55 owners? Well, for most HDR productions I still believe the best workflow is to shoot in S-Log3 and then to grade the footage to HDR. However there may be times when you need that direct HDR output. So for the FS7, F5 and F55 I have created a set of Hybrid Log Gamma LUT’s that you can use to bake in HLG and Rec2020 while you shoot. This gives you the same capabilities as the FS5 (with the exception of the ability to add HLG metadata to the HDMI).

For a video explanation of the process please follow the link to my new Patreon page where you will find the video and the downloadable LUT’s.

Looking For LUT’s for the Sony S-Log2 and S-Log3 Cameras?

This website has a great feature. If you look up in the top left corner of every page you will see a small magnifying glass symbol. If you click on that it will allow you to search the entire site for information… and there’s lots and lots of hint, tips and guides going back many years.

One thing though that a lot of people keep asking about is LUT’s or Look Up Tables. I have lots and they are all (for the moment at least) provided for free. There will be some paid LUT sets coming soon. If you follow the link below you will get a single page that lists all the current LUT articles on the web site. Links to my free LUT sets will be included in these articles.

Remember that LUT’s for S-Log2 and S-Log3 can be used in any camera with S-Log2 or S-Log3. So a LUT for the FS7 can also be used in the FS5 for example.

Here’s the link: http://www.xdcam-user.com/?s=LUT%27s

Using S-Log2 and S-Log3 with the Sony A6300 (with LUT’s to download).

Sony_A6300 Using S-Log2 and S-Log3 with the Sony A6300 (with LUT's to download).The new Sony A6300 is making quite a stir. This compact interchangeable lens camera has an amazing feature set that is very similar to the features found on it’s bigger brothers the A7sII and A7RII.

As a video camera it’s also capable recording using the XAVC-S codec in  both HD and UHD(4K). It can even shoot at 120fps in HD.  It also has picture profiles so you can tailor the look of the pictures or to suit different shooting conditions. The Cinegammas are very useful for challenging lighting conditions as they offer an improved highlight roll-off. As well as the Cinegammas the camera also has the S-Log2 and S-Log3 log gamma curves as well as S-Gamut, S-Gamut3 and S-Gamut3.cine.

Log gamma curves are very different to conventional gamma curves. Conventional gamma curves (like rec-709 or Cinegamma) are designed to produce a pleasing on screen image without any post production work (although the cinegammas do typically benefit with some tweaking in post). To do this conventional gammas keep the mid-range contrast compatible with conventional TV’s and monitors, so the picture has natural contrast when viewed on a TV. Then to help deal with bright highlights conventional gammas use some kind of highlight roll off or knee to increase the brightness range the camera can capture without effecting the mid range.  Unfortunately this means that the highlights are somewhat compromised, looking very flat, lacking contrast and this is often what gives video the “video look”. In addition it also means that if you are over exposed when you shoot, the picture will look bad and no amount of post production correction will ever make it look good. Most TV camera operators will be very familiar with the phrase “protect your highlights”, meaning don’t over expose, if anything under expose a tiny bit to keep the highlights looking good.

Log gamma curves such as S-Log2 and S-Log3 are very different.  They extended the dynamic range that the camera can capture. To do this they no longer try to be directly compatible with conventional TV’s and monitors and just focus on capturing the biggest possible range. The pictures will be made compatible with the TV or monitor via adjustments made during editing or in post production. So working with S-log2 and S-Log3 is a two step process – shooting and grading (grading is the term used for adjusting the look of an image in post production).

Because log gamma no longer needs to have a contrast range that matches the display range, more dynamic range can be squeezed into a conventional recording codec. It also means that there is no longer a need to use any highlight roll off or knee, so there is a lot more picture information in the highlights and brighter parts of the image. As a result exposing log gamma extra brightly is not normally a problem and in many cases brings lot of advantages. Log gamma curves do have a shadow roll off that mimics the real world shadow roll off. As a result log gammas really don’t like being under exposed, instead they prefer to be over exposed. So unlike conventional gamma where we “protect the highlights” with log gamma you need to “protect the shadows”. Under exposed log looks bad. It will lack color and it will be noisy and grainy.

For most camera operators it’s quite disconcerting to start shooting very slightly over exposed as it goes against everything you’ve learnt about shooting with a conventional video camera. But trust me, shooting 1 to 2 stops brighter than the recommended levels given by Sony on the A6300 (and any other Sony Log camera) will normally bring the best results.

I wrote a guide on how to do this with the Sony A7s here: http://www.xdcam-user.com/2014/08/exposing-and-using-slog2-on-the-sony-a7s-part-one-gamma-and-exposure/

The very same techniques can be used with the A6300, A7SII and A7RII. The A6300 etc also have S-Log3, but as these are 8 bit cameras (even when using an external recorder) I would still recommend that you use S-Log2. Besides, viewing and monitoring S-Log3 is tough as the pictures look even flatter than S-Log3.

If you follow the link below you will find a set of LUT’s (Look Up Tables) that can be applied to A6300 footage in post production to give different looks. There are some film-look LUT’s and 709 (normal TV look) LUT’s and in each case there are LUT’s for normal exposure as well as footage exposed 1 stop and 2 stops brighter. If a LUT name includes “1OVER” this means that the LUT is designed to work with footage that has been exposed 1 stop brighter than the levels given by Sony. My recommendation is to shoot at between 1 and 2 stops bright. For both S-Log2 and S-Log3 this would mean setting zebras to 70% and exposing a piece of white paper so that zebras are just starting to appear on the white paper.

If you find these LUT’s useful please consider buying me a coffee or a beer. I’m not paid to write these articles. For the LUT set I would appreciate a Cocktail, but am happy with whatever you feel is appropriate or affordable.


Type



pixel Using S-Log2 and S-Log3 with the Sony A6300 (with LUT's to download).

To download the LUT set please click the link: Alisters A6300 Mega LUT Kit

 

Set of 20 Cube LUT’s for the Sony A7S.

I’ve been doing a lot of work on shooting SLog-2 with the A7s. I realised almost straight away that a set of LUT’s for this camera would really help speed up my grading and testing. In addition as the camera is only 8 bit I have found that I am actually getting the best results from the Slog-2 if I over expose it just a little bit, depending of course on the scene. So I created a set of LUT’s that includes compensation for shooting at the nominal correct exposure as well as either 1 or 2 stops over exposed. In all there are 20 LUT’s in two sets. One is Rec-709 based LUT’s and the other Filmic LUT’s to act as starting points for further grading.

I am in the process of creating the complete workflow and SLog-2 guide for the A7s which I should be publishing later next week which will have much more information on how to use these LUT’s. But in the mean time here are the LUT’s if anyone want’s to play (and I would like feedback on what you think of them).

The LUT naming goes something like this:

AC A7S  709(800) ZERO

AC  (That’s me!).    A7S (The Camera).

709(800) = Output gamma or style.     ZERO = Exposure off set.

The exposure offset refers to the number of stops the footage is over exposed by relative to the normal SLog2 exposure level of Middle Grey at 32% and 90% white at 59%. ZERO menas no exposure offset. 1STOP would be used when the SLog2 was exposed 1STOP over and in this case the LUT then shifts the exposure back down 1 stop to compensate.

709 = Vanilla Rec-709, very contrasty, but limited highlight response and hard clip of over exposure.

709(800) = Rec-709 gamma with 800% (high) dynamic range. Will be slightly low contrast but deals much better with over exposure or bright highlights than vanilla 709.

Film-Like1 = An extended range gamma with highlight roll off (+400% range), slightly de-saturated, slightly more film like color (small red/yellow removed).

Filmic2 = Extended range low contrast gamma with very good over exposure handling. Slightly de-saturated. Good grading start point.

Filmic3 = Similar to Filmic2 but a little more contrast at the expense of a little less highlight roll off.

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.

Alisters A7S 709 LUTS v2

Alisters A7S Filmic LUTS set1
If you find the LUT’S useful, please consider buying me a beer or a coffee.


Type



pixel Set of 20 Cube LUT's for the Sony A7S.

Major Update to my Cine-EI guide for the PMW-F55 and PMW-F5

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.

http://www.xdcam-user.com/2013/12/cine-ei-mode-when-recording-s-log23-and-raw-on-the-f5-and-f55/

How to create a user LUT for the PMW-F5 or F55 in Resolve (or other grading software).

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.

LUT’s or LOOK’s when exposing via a LUT on the PMW-F5 or PMW-F55

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.

Exposing via LUT’s with the PMW-F5 and PMW-F55.

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.

log-exposure-1024x190 Exposing via LUT's with the PMW-F5 and PMW-F55.
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.