Tag Archives: PMW-F55

Revealing Signal to Noise and Exposure experiment for PMW-F5, F55 and FS7.

Here’s a little experiment for you to try if you have a PMW-F5, PMW-F55 or PMW-FS7. It should help you understand a few key things about the way these cameras behave, notably:

1: Why ISO does not actually reflect the sensitivity of the camera.

2: Why it is beneficial to expose S-Log2 or S-Log3 brighter than the Sony recommended levels.

3: How to get the best possible S-Log footage.

4: Why S-log may be a poor choice for low light.

Ideally you will want to use an external waveform monitor connected to the cameras SDI output, but it is possible to use the built in waveform display.

Start with the camera in Custom mode. Choose “STD” gamma and Rec-709. Set the gain/ISO settings so that the camera is showing ISO.

Set the ISO to the base ISO (800 ISO on F5/FS7, 500 ISO on F55).

Expose a 90% white card so that white is 90% on the waveform display. This doesn’t need to be 100% accurate, you can use a piece of paper if you don’t have a proper white card. Don’t change the ISO/Gain, light the white card if you need to. Make a note of the aperture.

Now change the gamma selection to S-Log2, do not change the exposure.

Note how white now drops down to about 70% and also note that the ISO becomes 2000 ISO on an F5 or FS7 and 1250 ISO on an F55.

Think about this for a moment: If the ISO has gone up, how can white and the bulk of my image become darker?

Now switch the camera to show dB gain instead of ISO, the gain should be showing 0dB. Repeat the above switching from Standard 709 gamma to S-Log2 and note that the gain remains at 0dB for both rec-709 and S-Log2.

Think about this: The gain is the same for both 709 and S-log2 but the S-Log2 image is darker. As the gain is NOT changing then the sensitivity is not actually changing, so why does the ISO change?

If you were to use a light meter and start off with the light meter set to 800 (500) ISO the light meter would tell you to set the aperture to whatever it is you currently have to give the correct exposure in rec-709 with white at 90%.  If you had a light meter and you change the ISO setting on the light meter from 800(500)ISO to 2000(1250) ISO the light meter will tell you to close the aperture by 1.3 stops.

So, on your camera, while it is set to S-Log2 close the aperture from it’s original setting by 1.3 stops. Now you will find that white will be at the recording levels given by Sony for S-Log2 which is 59% for white and 32% for middle grey.

So what have we learnt from this? The gain is the same for both standard gamma and S-Log2, even though the ISO changes from 800(500) to 2000(1250) ISO. So the sensitivity and amount of noise coming from the sensor is the same in both cases. But the indicated ISO changes so that if you are using an external light meter, when you switch to S-Log the higher indicated ISO  will make the light meter tell you to close the aperture. This means there is less light falling on the sensor. This means that the recorded image will have a worse signal to noise ratio (noise remains the same, but signal is smaller).

To solution of course to this poorer signal to noise ratio is simply to open the aperture back up again by 1.3 stops. When shooting S-Log2 or S-Log3 using the CineEI mode I always recommend using 800EI on an F5 or FS7 or 640EI on an F55. This means your aperture becomes the same as it would be when shooting in vanilla Rec-709, the end result is the same, improved, signal to noise ratio. If you are not using CineEI or LUT’s, then expose white at 70%.

New AXS-R7 raw recorder for the PMW-F55 and F5.

axsr7_3q_160219_011-1010x1024 New AXS-R7 raw recorder for the PMW-F55 and F5.
AXS-R7 dual slot raw recorder.

After a brief teaser campaign Sony have now released details of a new raw recorder for the PMW-F5 and PMW-F55 cameras.

The AXS-R7 is a new more rugged dual slot recorder that works with A series AXS cards (that’s the newer smaller size, not the original large size cards). Being dual slot it should allow for relay recording.

axsa1ts48_front_160219_051-300x300 New AXS-R7 raw recorder for the PMW-F55 and F5.
New A series AXS cards.

The new recorder has a lot more processing power than the original to support new functions such as cache recording up to 30 seconds and has a more rugged housing with dust and moisture filters. One of the new features coming with this recorder is the ability to record at up to 120 fps in 4K raw. For this new faster AXS cards will be needed and these will be released at the same time as the recorder this summer.

To support the new recorder the F5/F55 cameras will get new firmware. Version 8 will also introduce the ability to record XAVC class 480 which in 4K is 480Mb/s at 24/25/30p and 960Mb/s at 50 and 60p.

So all in all a series of significant upgrades for these cameras that continue to just get better and better.

axsr7_others_160219_031-1024x769 New AXS-R7 raw recorder for the PMW-F55 and F5.
AXS-R7 docked with PMW-F55

Here’s the full Sony press release:

Basingstoke – February 25th, 2016: Sony’s next generation of CineAlta products provides enhanced features for production professionals now shooting in 4K RAW with large sensor cameras; handling large files can be done easily while maintaining the highest levels of image quality.

The new products include an upcoming RAW recorder, the AXS-R7 for the F55/F5 and higher-speed AXS memory cards. These are complemented by the newest firmware (Version 8) for the F55 and F5, continuing Sony’s development and support of the CineAlta platform by adding new features and capabilities directly based on user feedback.

“These new technologies answer the question of ‘why shoot in 4K 16-bit RAW’? And, demonstrate Sony’s commitment to the F5 and F55’” said Ainara Porron, Marketing Manager, Cinematography, Sony Professional Solutions Europe. “Working in 4K RAW and High Dynamic Range (HDR) opens up new creative possibilities for production professionals who are not prepared to compromise on image quality.”

New RAW Recorder

Compared to previous Sony 4K recorders, the new recorder doubles 4K RAW recording from 60 FPS up to 120 FPS from the F55 camera. For shooting at higher frame rates, the recorder captures 2K RAW at up to 240 FPS from the F55 and F5, for playback with 10x super slow motion.

With the recorder, 4K shooters can take advantage of RAW cache recording at 23.98p for up to approximately 30 seconds while in standby mode, an important feature in documentary or wildlife production where capturing spontaneous action is required.

The new recorder is designed for rugged field performance. A metal filter separates and seals the recorder’s ventilation shaft from the electronics to prevent the entry of dust and water. The recorder’s camera connections are more secure, with a large top bracket that accepts four widely spaced 1/4-inch screws.

AXS Memory

The additions to the CineAlta line also include new high-performance versions of Sony’s AXS memory cards (1TB and 512 GB capacities) with sustained read and write speeds of 4.8 Gbps, and 44 minutes at 59.94p or 22 minutes at 120 FPS. The dual-slot recorder also accepts current A-series of AXS media, but the new cards are designed to support the write speeds required for 4K RAW 120 FPS recording for those who require that level of performance.

PMW-F55/F5 Firmware Version 8

The latest firmware update (Version 8) for the F55 and F5, upgrade license installed, enables support for XAVC 4K Class 480 recording at 23.98p, 24p, 25p and 29.97p. Leading third-party vendors already support XAVC 4K Class 480, for those creative professional requiring a higher data rate version of XAVC.

“These newest additions and updates to our CineAlta platform are all the direct result of user feedback,” Porron added. “It’s no longer about simply delivering a product. It’s about delivering the right products that can grow with a customer and fit within a workflow that is constantly evolving as production requirements change.”

For a full list of features and capabilities, visit pro.sony.eu/cinematography

Planned availability is as below:

[if !supportLists]·       [endif]AXS-R7 New RAW recorder: Summer 2016

[if !supportLists]·       [endif]AXS-A1TS48 Media (1TB): Summer 2016

[if !supportLists]·       [endif]AXS-A512S48 Media (512 GB): Summer 2016

[if !supportLists]·       [endif]Firmware version 8: Summer 2016

More details will be announced at NAB.

Sony PMW-F55 to get 4K raw at 120fps.

F554K-HFR-e1454834907993 Sony PMW-F55 to get 4K raw at 120fps.More good news for Sony PMW-F55 owners. A rather obscure announcement over on the official Sony user group states that the PMW-F55 will gain the ability to record 4K raw at up to 120fps via an optional future accessory.

This is great news for F55 owners. We can hope that perhaps this option will get extended to the F5 as well (after all the FS700 and  can do it for short bursts and possibly the FS5 will be able to do it too using their internal memory caches to cache 4 seconds of the 4K HFR before copying it to the R5 or Odyssey).  I do hope that the F55 4K raw isn’t limited to a 4 second burst and that it’s the full 16 bit raw that you get at up to 60fps.

Quite what the optional accessory will be I don’t know, but my guess would be a new raw recorder or new faster AXS media, but it could also be an internal upgrade allow the high speed raw to be passed to the existing R5 and AXS media.

So, if I can hack an F5 for 4K, can I also get the F55’s color gamut?

So, we have seen that it is possible to trick an F5 into thinking its an F55 by altering an all file from the F5 and adding some F55 4K settings. This enables 4K internal recording and 4K output over HDMI on the F5. Internal 4K is one of the key differences between the lower cost F5 and the much more expensive F55. Another major difference is that the F55 has a global shutter so no CMOS image skew or other rolling shutter artefacts and the F55 has a larger colour gamut allowing better colour rendition and capture.

A question that has been asked is: Well if we can get 4K, can we also enable the larger colour gamut? One thing we do know is that the sensor used in the F55 is different to the sensor in the F5 as the sensor is replaced if you upgrade your F5 to an F55.

A cameras gamut is determined more by the sensors colour filters than the recording gamut. The recording gamut is like a bucket, the sensor a scoop. If the scoop isn’t big enough you won’t fill the bucket.

The color filters on the F55 are very different to those in the F5, so the F55 can capture a much greater gamut than the F5.

If you think about it, if you hold a red gel up infront of your eyes you will only see an extremely narrow colour gamut, just a single narrow part of the red spectrum. Imagine if you have a red, green and blue filter, you will now see a bit of red, a bit of green and a bit of blue. But you might only see a very narrow part of the full blue spectrum or a very narrow part of red or of green, you won’t see the full spectrum or a large gamut, just narrow slithers of it. The trick is to make filters that are wide enough and with the righ charcteristics to pass all of the R, G and B spectrum but sharply cut off unwanted colors, infra-red or UV at the exactly the right point. This is very hard to do. So the quality and accuracy of the color filters determines both the gamut and the precision of the colors that the camera can capture.

In practice it can be hard to see this difference as none of the monitors available today can show the full gamut that the F55 can capture so you can’t directly see it. But it does make a difference in post as the F55 is able to separate subtle hues more accurately and capture an extended tonal range, for example very subtle differences in skin tones that may be lost on a camera with poorer filters. This means when grading you are able to draw more tonal information out of the image when you transform the color space in to Rec 709 or DCI-P3 and it results in a more natural looking image.

The F5’s sensor gamut is probably somewhere around the size of DCI P3, maybe a bit bigger, but it’s clearly not as big as the F55’s. In addition the colour precision is not as great so some subtle tones are lost. It’s not a massive difference and the F5 does a great job. It’s not something that can be changed with software, it’s all down to the sensor hardware. The F5 just can’t fill the S-Gamut recording bucket so by using S-Gamut your wasting a lot of data. By using a smaller recording gamut like S-Gamut3.cine you can more effectively fill the bucket and make better use of the data available to you.

Hack to get internal 4K on the Sony PMW-F5 CAUTION THERE MAY BE ISSUES!!!!

STOP PRESS: It’s been found that this modification is also changing the exposure and dynamic range! See bottom of post.

Well, Paul Ream over at http://extrashot.co.uk/ has worked out how to make the F5 record 4K internally. It’s actually pretty straight forward. The camera can save a file called an “All File” on an SD card to memorise the way it’s set up. By mdifying this file you can trick the F5 to go into 4K or UHD frame size instead of the usual HD or 2K. First you have to modify line 15o of an existing All File (they are simple text files) where the frame rate and frame size are saved using a text editor, putting in the frame size you want. Then delete line 1 where the files MD5 checksum is stored. Save the file. Next determine the checksum of the file, then add the new checksum to line 1 and finally save the file to the SD card and read it in to the camera. By loading this modified (hacked???) all file in to the camera you can enable 4K and UHD recording to the SxS cards.

It’s certainly created a stir. Many F55 owners think they have been short changed because of this hack and of course most F5 are very happy. It will be interesting to see if any other F55 features can be unlocked on the F5 such as 4K output or 4K playback. Right now the hack is a little limited as you can’t even playback files to see if they are OK. Full details over on Extrashot in the latest podcast…. if you can grind your way through the bit on shoes and iphones without nodding off first.

UPDATE: So, now a few people have tried this, there have been a couple of reports of the dynamic range of image clipping and some other issues. I’ve had a quick look on an F5 (not mine, I’m travelling) and there is most definitely something odd going on as the pictures are darker and clip earlier in 4K XAVC compared to HD and 2K. I need to test this further to see what’s going on, but it’s not quite as perfect as perhaps hoped.

What we know: The hack tricks the camera into behaving like a PMW-F55. We know the F5 and F55 have different sensors with very different behaviour, different colour filters and different sensitivity, so the processing must be different for these two cameras.

My very quick test, shooting the same scene in 4K and in normal HD XAVC shows the 4K to be darker. Others are reporting that the 4K clips appear to over-exposure more readily than the HD.

SPECULATION: If the hack is doing more than just turning on 4K recording, if it is making the camera use the F55’s processing, then there will be a miss-match between the sensor and the processing and this might cause issues with dynamic range, gain and colour.

As soon as I get a chance (should be tomorrow) I will do some more involved testing to see exactly what is going on.

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 (and FS7).

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.

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

INTRODUCTION:

This guide to Cine-EI is based on my own experience with the Sony PMW-F5 and F55. There are other methods of using LUT’s and CineEI. The method I describe below, to the best of my knowledge, follows standard industry practice for working with a camera that uses EI gain and LUT’s.

If you find the guide useful, please consider buying me a beer or a coffee. It took quite a while to prepare this guide and writing can be thirsty work.


Type



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

If you want you can download this guide as a PDF by clicking on this link: Ultimate Guide to CineEI on the PMW. I’d really appreciate a drink if your going to take away the PDF.

In this guide I hope to help you get the very best from the Cine EI mode on Sony’s PMW-F5 and PMW-F55 cameras. The cameras have two very distinct shooting mode, Cine EI and Custom Mode. In custom mode the camera behaves much like any other traditional video camera where what you see in the viewfinder is what’s recorded on the cards. In custom mode you can change many of the cameras settings such as gamma, matrix, sharpness to create the look you are after in-camera. “Baking-in” the look of your image in camera is great for content that will go direct to air or for fast turn around productions. But a baked-in look can be difficult to alter in post production. In addition it is very hard to squeeze every last drop of picture information in to the recordings in this mode.

The other mode, Cine-EI, is primarily designed to allow you to record as much information about the scene as possible. The footage from the camera becoming in effect a “digital negative” that can then be developed in post and the final highly polished look of the film or video created. In addition the Cine-EI mode mimics the way a film camera works giving the cinematographer the ability to rate the camera at different ISO’s to those specified by Sony. This can be used to alter the noise levels in the footage or to help deal with difficult lighting situations.

One further “non-standard” way to use Cine-EI is to use a LUT (Look Up Table) to create an in-camera look that can be baked in to the footage while you shoot. This offers an alternative to custom mode. Some users will find it easier to create a specific look for the camera using a LUT than they would by adjusting camera settings such as gamma and matrix.

MLUT’s, LUT’s and LOOK’s (all types of Look Up Tables) are only available in the Cine-EI mode.

THE SIMPLIFIED VERSION:

Before I go through all the “why’” and “hows” first of all let me just say that actually CineEI is easy. I’ve gone in to a lot of extra detail here so that you can full master the mode and the concepts behind it.

But in it’s simplest form, all you need to do is to turn on the MLUT’s. Choose the MLUT that you like the look of, or is closest to the final look you are after. Expose so that the picture in the viewfinder or on your monitor looks how you want and away you go.

Then in post production bring in your Slog footage. Apply the same LUT as you used when you shot and the footage will look as shot, only as the underlying footage is either raw or Slog you have a huge range of adjustment available to you in post.

THAT’S IT! If you want, it’s that simple.

If you want to get fancy you can create your own LUT and that’s really easy too (see the end of the document). If you want less noise in your pictures use a lower EI. I shoot using 800EI on my F5 and 640EI on the F55 almost all the time.

Got an issue with a very bright scene and strong highlights, shoot with a high EI.

Again, it’s really simple.

But anyway, lets learn all about it and why it works the way it works.

LATITUDE AND SENSITIVITY.

The latitude and sensitivity of the F5/F55, like most cameras is primarily governed by the latitude and sensitivity of the sensor. The latitude of the sensor in these cameras is around 14 stops. Adding different amounts of conventional camera gain or using  different ISO’s does not alter the sensors actual sensitivity to light, only how much the signal from the sensor is amplified. Like turning up or down the volume on a radio, the sound level gets higher or lower, but the strength of the radio signal is just the same. Turn it up loud and not only does the music get louder but also any hiss or noise, the ratio of signal to noise does not change, they BOTH get louder. Turn it up too loud and it will distort. If you don’t turn it up loud enough, you can’t hear it, but the radio signal itself does not change. It’s the same with the cameras sensor. It always has the same sensitivity, but with a conventional camera we can add or take away gain (volume control?) to make the pictures brighter or darker (louder?).

NATIVE ISO:

Sony’s native ISO ratings for the cameras, 1250ISO for the F55 and 2000ISO for the F5 are values chosen by Sony that give a good trade off between sensitivity, noise and over/under exposure latitude. In general these native ISO’s will give excellent results. But there may be situations where you want or need different performance. For example you might prefer to trade off a little bit of over exposure headroom for a better signal to noise ratio, giving a cleaner picture. Or you might need a very large amount of over exposure headroom to deal with a a scene with lots of bright highlights.

The Cine EI mode allows you to change the effective ISO rating of the camera.

With film stocks the manufacturer will determine the sensitivity of the film and give it an Exposure Index which is normally the equivalent of the films measured ASA/ISO.  It is possible for a skilled cinematographer to rate the film stock with a higher or lower ISO than the manufacturers rating to vary the look or compensate for filters and other factors. You then adjust the film developing and processing to give a correctly exposed looking image. This is a common tool used by cinematographers to modify the look of the film, but the film stock itself does not actually change it’s base sensitivity, it’s still the same film stock with the same base ASA/ISO.

Sony’s Cine EI and EI modes on Red and Alexa are very similar. While it has many similarities to adding conventional video camera gain, the outcome and effect can be quite different. If you have not used it before it can be a little confusing, but once you understand the way it works it is very useful and a great way to shoot. Again, remember that the actual sensitivity of the sensor itself never changes.

CONVENTIONAL VIDEO CAMERA GAIN.

Increasing conventional camera gain will reduce the cameras dynamic range as something that is recorded at maximum brightness (109%) at the native ISO would be pushed up above the peak recording level and into clipping if the conventional camera gain was increased because we can’t record a signal larger than 109%. But as the true sensitivity of the sensor does not change, the darkest object the camera can actually detect remains the same. Dark objects may appear a bit brighter, but there is still a finite limit to how dark an object the camera can actually see and this is governed by the sensors noise floor and signal to noise ratio (from the sensors own background noise). Any very dark picture information will be hidden in the sensors noise. Adding gain will bring up both the noise and darkest picture information, so anything hidden in the noise at the native ISO (or 0db) will still be hidden in the noise at a higher gain or ISO as both the noise and small signal are amplified by the same amount.

Using negative conventional gain or going lower than the native ISO may also reduce dynamic range as picture information very close to black may be shifted down below black when you subtract gain or lower the ISO. At the same time there is a limit to how much light the sensor can deal with before the sensor itself overloads. So even though reducing the ISO or gain may make the picture darker, the sensor clipping/overload point remains the same, so there is no change to the upper dynamic range, just a reduction in recording level.

See also this article on gain and dynamic range.

As Sony’s Slog2 and Slog3 are tailored to capture the cameras full 14 stop range this means that when shooting with Slog2 or Slog3 the gamma curve will only work as designed and deliver the maximum dynamic range when the camera is at it’s native ISO. At any other recording ISO or gain level the dynamic range will be reduced. IE: If you were to use SLog2 or SLog3 with the camera in custom mode and not use the native ISO by adding gain or changing the ISO, you will not get the full 14 stop range that the camera is capable of delivering.

EXPOSURE LEVELS FOR DIFFERENT GAMMA CURVES AND CONTRAST RANGES.

It’s important to know (or better still understand) that different gamma curves with different contrast ranges will require different exposure levels. The TV system that we use today is currently based around a standard known as Rec-709. This standard specifies the contrast range that a TV set or monitor can show and which recording levels represent which display brightness levels. Most tradition TV cameras are also based on this standard. Rec-709 does have some serious restrictions, the brightness and contrast range is very limited as these standards are based around TV standards and technologies developed 50 years ago. To get around this issue most TV cameras use methods such as a “knee” to compress together some of the brighter part of the scene into a very small recording range.

Slide2 Cine-EI Mode when recording S-Log2/3 and raw on the F5 and F55.
A traditional TV camera with a limited dynamic range compresses only a small highlight range.

 

As you can see in the illustration above only a very small part of the recording “bucket” is used to hold a moderately large compressed highlight range. In addition a typical TV camera can’t capture all of the range in many scenes anyway. The most important parts of the scene from black to white is captured more or less “as is”. This leaves just a tiny bit of space above white to squeeze in a few highly compressed highlights. The signal from the TV camera is then passed directly to the TV and as the shadows, mid range and skin tones etc are all at more or less the same level as captured the bulk of scene looks OK on the TV/Monitor. Highlights may look a little “electronic” due to the very large amount of compression used.

But what happens if we want to record more of the scenes range? As the size of the recording “bucket”, the codec etc, does not change, in order to capture a greater range and fit it in to the same space, we have to re-distribute how we record things.

Slide3 Cine-EI Mode when recording S-Log2/3 and raw on the F5 and F55.
Recording a greater dynamic range into the same sized bucket.

Above you can see that instead of just compressing a small part of the highlights we are now capturing the full dynamic range of the scene. To do this we have altered the levels that everything is recorded at. Blacks and shadows are a little lower, greys and mids are a fair bit lower and white is a lot lower. By bringing all these levels down we make room for the highlights and the really bright stuff to be recorded without being excessively compressed.

The problem with this though is that when you output the picture to a monitor or TV it looks odd. It will lack contrast as the really bright stuff is displayed at the same brightness as the conventional 709 highlights. White is now only as bright as faces would be with a conventional TV camera and Faces are only a little bit above the middle grey level.

This is how Slog works. By re-distributing the recording levels we can squeeze a much bigger dynamic range into the same size recording bucket. But it won’t look quite right when viewed directly on a standard TV or monitor. It may look dark and certainly a bit washed out.

I hope you can also see from this that whenever the cameras gamma curve does not match that of the TV/Monitor the picture might not look quite right. Even when correctly exposed white may be at different levels, depending on the gamma being used, especially if the gamma curve has a greater range than the normal Rec-709 used in old school TV cameras.

THE CORRECT EXPOSURE LEVELS FOR SLOG-2 and SLOG-3.

Lets look at the correct exposure levels for SLog-2 and SLog-3. As these gamma curves have a very large dynamic range the recording levels that they use are different to the levels used by the normal 709 gamma curve used for conventional TV. As a result when correctly exposed, Slog looks dark and low contrast on a conventional monitor or in the viewfinder. The table below has the correct levels for middle grey and 90% reflectance white for the different types of Slog.

log-exposure-1024x190 Cine-EI Mode when recording S-Log2/3 and raw on the F5 and F55.
Correct exposure levels for Sony’s Slog.

The white level in particular is a lot lower than we would normally use for TV gamma. This is done to make extra space above white to fit in the extended range that the camera is capable of capturing, all those bright highlights, bright sky and clouds and other things that cameras with a smaller dynamic range struggle to capture.

Let’s now take a look at how to set the correct starting point exposure for SLog-3. You can use a light meter if you wish, but if you do want to use a light meter I would first suggest you check the calibration of the light meter by using the grey card method below and comparing the what the light meter tells you with the results you get with a grey or white card.

The most accurate method is to use a good quality grey card and a waveform display. For the screen shots seen here I used a Lastolite EzyBalance Calibration Card. This is a pop up grey card/white card that fits in a pocket but expands to about 30cm/1ft across giving a decent sized target. It has middle grey on one side and 90% reflectance white on the other. With the MLUT’s off, set the exposure so that the grey card is exposed at the appropriate level (see table above).

Note: To get the waveform to display you must have BOTH the SDI SUB and Viewfinder MLUT’s OFF or BOTH ON. The waveform is turned on and off under the  “VF” – “Display ON/OFF” – “Video Signal Monitor” settings of the main menu. Sadly the cameras built in waveform display is not the best so it may help to use an external monitor with a better waveform display.

LUT-middlegrey41 Cine-EI Mode when recording S-Log2/3 and raw on the F5 and F55.
Setting the correct exposure for Slog-3 using a grey card. Middle Grey should be 41%

If you don’t have access to a better waveform display you can use a 90% reflectance white card and zebras. By setting up the Zebras with a narrow aperture window of around 3% you can get a very accurate exposure assessment for various shades of white. For SLog-3 set the Zebras to 3% aperture and the level at 61%. Sadly the zebras don’t go below 60%. For Slog-2 using 60% will be accurate enough, a 1% error is not going to do any real harm. You can use exactly the same method for S-Log2 just by using the SLog-2 levels detailed in the chart above.

zebras61 Cine-EI Mode when recording S-Log2/3 and raw on the F5 and F55.
Setting up the Zebras to measure S-Log3 exposure of white card (90% reflectance white card).
LUT-white61 Cine-EI Mode when recording S-Log2/3 and raw on the F5 and F55.
Correct exposure for S-Log3 when using a 90% reflectance white target.

The image above shows the use of both the Zebras and Waveform to establish the correct exposure level for S-Log3 when using a 90% reflectance white card or similar target. Please note that very often a piece of white paper or a white car etc will be a little bit brighter than a calibrated 90% white card. If using typical bleached white printer paper I suggest you add around 4% to the white values in the above chart to prevent under exposure.

SO HOW DOES CINE-EI WORK?

cine-ei-menu-small Cine-EI Mode when recording S-Log2/3 and raw on the F5 and F55.
Cine EI is selected in the Base Settings page. It works in YPbPr, RGB and Raw main operation modes.

Cine-EI (Exposure Index) works differently to conventional camera gain. It’s operation is similar in other cameras that use Cine-EI or EI gain such as the F5, F55, F3, F65, Red or Alexa. You enable Cine-EI mode in the camera menus Base Settings page. On the F5 and F55 it works in YPbPr, RGB and RAW modes.

IMPORTANT: In the Cine-EI mode the ISO of the recordings remains fixed at the cameras native ISO (unless baking in a LUT,  more on that later). By always recording at the cameras native ISO you will always have 14 stops of dynamic range.

YOU NEED TO USE A LUT:

Important: For Cine-EI mode to work as expected you should monitor your pictures in the viewfinder or via the SDI/HDMI output through one of the cameras built in MLUT’s (Look Up Table), LOOK’s or User3D LUT’s. So make sure you have the MLUT’s turned on. If you don’t have a LUT then it won’t work as expected because the EI gain is applied to the cameras LUT’s.  At this stage just set the MLUT’s to on for the Sub&HDMI output and the Viewfinder out.

Lut-menu-page-on Cine-EI Mode when recording S-Log2/3 and raw on the F5 and F55.
For CineEI to work correctly you MUST turn on the LUT’s for the Viewfinder and/or Sub&HDMI output.
LUT-Camera-Button2 Cine-EI Mode when recording S-Log2/3 and raw on the F5 and F55.
You can turn the MLUT’s on and off by pressing the CAMERA button until you see the MLUT controls, then use the hotkeys to turn the MLUT’s on and off.

EXPOSING VIA THE LUT/LOOK.

At the cameras native ISO (2000 on F5, 1250 on F55), when shooting via a LUT you should adjust your exposure so that the picture in the viewfinder looks correctly exposed. If the LUT is correctly exposed then so too will the S-log. As a point of reference, middle grey for Rec-709 and the 709(800) LUT should be at, or close to 42%.

This is really quite simple, generally speaking when using a LUT, if it looks right, it probably is right. However it is worth noting that different LUT’s may have slightly different optimum exposure levels. For example the 709(800) LUT is designed to be a very close match to the 709 gamma curve used in the majority of monitors, so this particular LUT is really simple to use because if the picture looks normal on the monitor then your exposure will also be normal.

LUT-middlegrey42 Cine-EI Mode when recording S-Log2/3 and raw on the F5 and F55.
Correct exposure of Middle Grey for the 709(800) MLUT. Middle Grey should be 42%. 90% will be 90%.
LUT-white90 Cine-EI Mode when recording S-Log2/3 and raw on the F5 and F55.
Correct exposure of the 709(800) LUT using a 90% white card, white will be 90%. You can use zebras at 90% to check this level.

The above images show the correct exposure levels for the 709(800) LUT. Middle grey should be 42% and 90% white is… well 90%. Very simple and you can easily use zebras to check the white level by setting them to 90%. As middle grey is where it normally is on a TV or monitor and white is also where you would expect to see it, when using the 709(800) LUT, if the picture looks right in the viewfinder then it generally is right. This means that the 709(800) LUT is particularly well suited to being used to set exposure as a correctly exposed scene will look “normal” on a 709 TV or monitor.

Many of the other LUT’s and Looks however capture a contrast range that far exceeds the Rec-709 standard used in most monitors. So you may need to adjust your exposure levels slightly to allow for this.

The LC709-TypeA Look is very popular as a LUT for the PMW-F5 and F55 as it closely mimics the images you get from an Arri Alexa (“type A” = type Arri).

The “LC” part of the Look’s name means Low Contrast and this also means – big dynamic range. Whenever you take a big dynamic range (lots of shades) and show it on a display with a limited dynamic range (limited shades) all the shades in the image get squeezed together to fit into the monitors limited range and as a result the contrast gets reduced. This also means that middle grey and white are also squeezed closer together. With conventional 709 middle grey would be 42% and white around 80-90%, but with a high dynamic range/low Contrast gamma curve white gets squeezed closer to grey to make room for the extra dynamic range. This means that middle grey will remain close to 42% but white reduces to around 72%. So for the LC709 Looks in the F5/F55 optimum exposure is to have middle grey at 42% and white at 72%. Don’t worry too much if you don’t hit those exact numbers, a little bit either way does little harm.

LUT-white72 Cine-EI Mode when recording S-Log2/3 and raw on the F5 and F55.
Correct white level for the LC709 LOOK’s. White should be around 72%

 

RECOMMENDED LUT EXPOSURE LEVELS.

Here are some white levels for some of the built in LUT’s. The G40 or G33 part of the HG LUT’s is the recommended value for middle grey. Use these levels for the zebras if you want to check the correct exposure of a 90% reflectance white card. I have also include an approximate zebra value for a piece of typical white printer paper.

709(800) = Middle Grey 42%. 90% Reflectance white 90%, white paper 92%.

HG8009(G40) = Middle Grey 40%. 90% Reflectance white 83%, white paper 86%.

HG8009(G33) = Middle Grey 33%. 90% Reflectance white 75%, white paper 80%.

The “LC709” LOOK’s = Middle Grey 42%. 90% Reflectance white 72%, white paper 77%.

DONT PANIC if you don’t get these precise levels! I’m giving them to you here so you have a good starting point. A little bit either way will not hurt. Again, generally speaking if it looks right in the viewfinder or on your monitor screen, it is probably close enough not to worry about it.

If you ever need to confirm the correct levels for any given LUT or Look it’s really easy. Put the camera in to CineEI.  Turn OFF the MLUT’s (remember you can turn LUT’s on and off from the cameras side information screen by pressing the CAMERA menu button until you see the LUT options at the bottom of the display). With the MLUT’s OFF use a grey card or white card (or maybe your calibrated light meter) to set the exposure for the Slog curve you have chosen.

Once you have established the correct exposure for the SLog, without adjusting anything else, turn on the MLUT’s, ensure the camera is at the native ISO and choose the LUT or LOOK that you want to check.  Now you can measure the grey and white point for the LUT/Look you have chosen and see on the monitor or in the viewfinder what the correct exposure looks like via the LUT. It probably won’t be vastly different from normal 709 in most cases, especially middle grey this tends to stay very close to 42%, but it’s useful to do this check if you are at all unsure.

If  you can, use a LUT, not a LOOK. That’s my recommendation, not a hard and fast rule but if you’re new to CineEI, LUT’s and Looks please read on as to why I say this. Otherwise skip on to Baking-in the LUT/LOOK.

I recommend that for exposure evaluation you should normally try to use one of the cameras built in  MLUT’s not the LOOK’s. Especially if you are new to LUT’s and Looks. This is because the LUT’s behave differently to the Looks when you use a high or low EI.

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 is only very slight). 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 with the LOOK’s.

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 built in LUT’s don’t cover the full range of the Slog curves so you will never see all of your dynamic range at all 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 1D LUT’s range is less than Slog’s range, but the LUT itself does not clip, instead highlights just go up above 109% where you can’t see them and this in my opinion is 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, but my recommendation is to use the LUT’s rather than the LOOK’s when judging exposure.

Using the built in MLUT’s?

There are 5 built in MLUT’s: P1 709(800), P2 HG8009G40, P3 HG8009G33, P4 Slog2, P5 Slog3. You can only select the Slog2 LUT when the camera is set to SLog2 in the base settings, the same for the SLog3 LUT. You can also create your own 1D LUT’s in Sony’s Raw Viewer software and user 3D LOOK’s in most grading suites but that’s a whole other subject that I’m not going to cover right here (see this article for user 3D Look creation or go to the additional LUT creation section at the bottom of this document), for now lets just consider the built in LUT’s.

All 3 of the other built in LUTs have an 800% exposure range. The camera itself  has a 1300% exposure range when your shooting in CineEI, Raw,  SLog2 or SLog3 (1300% more than standard gamma). So if you want to see your full exposure range then you should select SLog as your LUT or turn the LUT’s off. However the pictures will be flat looking and lack contrast, which makes accurate focussing harder and you must set your exposure using the SLog levels given above, so in addition Slog 2 will look dark. Note that if you press the “camera” button by the side LCD screen 2 times you can use the hot keys around the LCD to change LUT and turn the LUT’s on and off.

If you use MLUT’s P1, P2 orP3 then the viewfinder pictures will have near “normal” contrast. Your exposure levels will be more normal looking (although P3 should have middle grey at 33% so should look a touch darker than normal) but you won’t be seeing the full recorded range, only 800% out of the possible 1300% is displayed, so some things might look clipped in the viewfinder while the actual recording is not. I suggest switching  the LUT’s off momentarily to check this, or connect a second monitor to the Main SDI to monitor the non LUT output. Do note that if using Slog2/Slog3 as a LUT and at a positive EI ISO you won’t see your full recording range. You will still see up to a stop more than the 800% LUT’s but at high EI’s the Slog2 or Slog3 LUT will clip slightly before the camera recordings. At low EI’s the Slog LUT’s will clip at the same time as the camera, but the level of the clipping point on any waveform display via the LUT output will be lower and this can be a little confusing. Unfortunately if you turn off the LUT’s you can’t get the cameras built in waveform display. This is where an external monitor with waveform becomes very handy to monitor the non LUT native ISO Slog output from the main HDSDI output.

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. The slightly restricted range will help highlight any contrast issue that may cause problems in post. It’s often easier to solve these issues when shooting rather than leaving it to later. 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.

BAKING IN THE LUT/LOOK.

When shooting using a high or low EI, the EI gain is added or subtracted from the LUT or LOOK, this makes the picture in the viewfinder or monitor fed via the LUT brighter or darker depending on the EI used. In Cine-EI mode you want the camera to always actually record the raw and S-Log2/S-log3 at the cameras native ISO (1250 ISO for F55 or 2000 ISO for F5). So normally you want to leave the LUT’s OFF for the internal recording. Just in case you missed that very important point: normally you want to leave the LUT’s OFF for the internal recording!

Lut-menu-page-sxs-off Cine-EI Mode when recording S-Log2/3 and raw on the F5 and F55.
Normally in CineEI you need to ensure that the LUT is OFF for the Main&Internal so that there is no LUT added to the SxS recordings.

Just about the only exceptions to this might be when shooting raw or when you want to deliberately record with the LUT/Look baked in to your SxS recordings. By “baked-in” I mean with the gamma, contrast and color of the LUT/Look permanently recorded as part of the recording. You can’t remove this LUT/look later if it’s “baked-in”.

No matter what the LUT/Look settings, if you’re recording raw on the R5 raw recorder the raw is always recorded at the native ISO.  But the internal SxS recordings are different. It is possible, if you choose, to apply a LUT/LOOK to the SxS recordings by setting the “Main&Internal” MLUT to ON. The gain of the recorded LUT/LOOK will be altered according to the CineEI gain settings. This might be useful to provide an easy to work with proxy file for editing, with the LUT/LOOK baked-in while shooting raw. Or as a way create an in-camera look or style for material that won’t be graded. Using a baked-in LUT/LOOK for a production that won’t be graded or only have minimal grading is an interesting alternative to using Custom Mode that should be considered for fast turn-around productions.

In most cases however you will probably not have a LUT applied to your primary recordings. If shooting in S-Log2 or S-Log3 you must set MLUT – OFF for “Main&Internal” See the image above. With “Main&Internal MLUT OFF” the internal recordings, without LUT, will be SLog2 or Slog3 and at the cameras native ISO.

You can tell what it is that the camera is actually recording by looking in the viewfinder. At the center right side of the display there is an indication of what is being recorded on the cards. Normally for Cine-EI this should say either SLog2 or Slog3. If it indicates something else, then you are baking the LUT in to the internal recordings.

LUT-Slog3-indication Cine-EI Mode when recording S-Log2/3 and raw on the F5 and F55.
The internal recording gamma is shown on the right of the VF. This is recording SLog-3

 

LUT-LUT709-indication Cine-EI Mode when recording S-Log2/3 and raw on the F5 and F55.
The indication here shows that the 709(800) LUT is being baked-in to the internal recordings.

CHANGING THE EI.

Latitude Indication.

At the native ISO you have 6 stops of over exposure latitude. This is how much headroom your shot has. Your over exposure latitude is indicated on the cameras side LCD panel as highlight latitude.

EI-indication Cine-EI Mode when recording S-Log2/3 and raw on the F5 and F55.
High light range indicated in “High Latitude” box as 6E or +6 stops. EI is 2000 (native F5 ISO)

REDUCING THE EI.

So what happens when you halve the EI gain to 1000EI?  1 stop of ISO will subtracted from the LUT. As a result the picture you see via the LUT becomes one stop darker (a good thing to know is that 1 stop of exposure is the same as 6db of gain or a doubling or halving of the ISO). So the picture in the viewfinder gets darker. But also remember that the camera will still be recording at the native ISO (unless baking-in the LUT).

EI-1000iso-indication Cine-EI Mode when recording S-Log2/3 and raw on the F5 and F55.
With the EI reduced to 1000EI from the native 2000EI the High Latitude decreases to 5.0E or +5 stops.

As you can see from the side panel indication, the cameras highlight latitude decreases by 1 stop.

Why does this happen and whats happening to my pictures?

First of all lets take a look at the scene, as seen in the cameras viewfinder when we are at the native EI (This would be 1250 on the F55 and 2000ISO on an F5) and then with the EI changed one stop down so it becomes 500EI on F55 or 1000EI on the F5. The native ISO on the left, the one stop lower EI on the right.

VF-side-by-side Cine-EI Mode when recording S-Log2/3 and raw on the F5 and F55.
2000EI and 1000EI as seen in the viewfinder of an F5 with NO exposure change.

So, in the viewfinder, when we lower our EI by one stop (halving the EI) the picture becomes darker by 1 stop. Note that if you were using the waveform display or histogram the indicated levels would also become lower. The waveform, histogram and zebras all measure the output from the LUT or the image seen in the viewfinder. So as this becomes one stop darker, they would also read 1 stop darker/lower. If using an external monitor with a waveform display connected to the SDI SUB out (SDI’s 3&4) or HDMI and the LUT is enabled for “Sub&HDMI” this too would get darker and the levels decrease by one stop.

What do you do when you have a dark picture? Well most people would normally compensate for a dark looking image by opening the iris to compensate. As we have gone one stop darker with the EI gain, to return the viewfinder image back to the same brightness as it was at the native EI you would open the iris by one stop.

If using a light meter you would start with the meter set at 2000/1250 ISO and set your exposure according to the what the meter tells you. Then you reduce your EI gain on the camera (the viewfinder image gets darker). Now you also change your ISO on the light meter to the new EI ISO. The light meter will then tell you to open the iris by one stop.

So now, after reducing the EI by one stop and then compensating by opening the iris by 1 stop, the viewfinder image is the same brightness as it was when we started.

But what’s happening to my recordings?

Remember the recordings, whether on the SxS card (assuming the Main&Internal LUT is OFF) or RAW always happens at the cameras native ISO (2000 on the F5 and 1250 on the F55), no matter what the EI is set to. As a result, because we opened the iris by 1 stop to compensate for the dark viewfinder or new light meter reading the recording will have become 1 stop brighter. Look at the image below to see what we see in the viewfinder alongside what is actually being recorded. The EI offset exposure as seen in the viewfinder (left hand side) looks normal, while the actual native ISO recording (right hand side) is 1 stop brighter.

VF-and-Internal Cine-EI Mode when recording S-Log2/3 and raw on the F5 and F55.
At 1000EI the Viewfinder image on the left is 1 stop darker than the actual recorded image (on the right) which is recorded at the native 2000 ISO (F5).

How does this help us, what are the benefits?

When I take this brighter recorded image in to post production I will have to bring the levels back down to normal as part of the grading process. As I will be reducing my levels in post production by around 1 stop (6db) any noise in the picture will also be reduced by 6db. The end result is a picture with 6db less noise than if I had shot at the native ISO. Another benefit may be that as the scene was exposed brighter I will be able to see more shadow information.

Is there a down side to using a low EI?

Because the actual recorded exposure is brighter by one stop I have one stop less headroom. However the F5 and F55 have an abundance of headroom so the loss of one stop is often not going to cause a problem. I find that going between 1 and 1.5 EI stops down rarely results in highlight issues. But when shooting very high contrast scenes and using a low EI it is worth toggling the LUT on and off to check for clipping in the SLog image. This can be done from the side panel of the camera by pressing the “Camera” button until you see the MLUT controls on the side display and turning the MLUT on or off.

What is happening to my exposure range?

What you are doing is moving the mid point of your exposure range up in the case of a lower EI. This allows the camera to see deeper into the shadows but reduces the over exposure latitude. The reverse is also possible. If you use a higher EI you shift your mid point down. This gives you more headroom for dealing with very bright highlights, but you won’t see as far into the shadows and the final pictures will be a little noisier as in post production the overall levels will have to be brought up to compensate for the darker overall recordings.

Cine-EI allows us to shift our exposure mid point up and down.  Lowering the EI gain gives you a darker VF image so you tend to overexpose the actual recording which reduces over exposure headroom but increases under exposure range (and improves the signal to noise ratio). Adding EI gain gives a brighter Viewfinder image which makes you underexpose the recordings, which gives you more headroom but with less underexposure range (and a worse signal to noise ratio).

Slide1 Cine-EI Mode when recording S-Log2/3 and raw on the F5 and F55.
Cine EI moves the exposure mid point up and down.

Post Production.

When shooting raw information about the EI gain is stored in the clips metadata. The idea is that this metadata can be used by the grading or editing software to adjust the clips exposure level in the edit or grading application so that it looks correctly exposed (or at least exposed as you saw it in the viewfinder via the LUT). The metadata information is recorded alongside the XAVC or SSTP footage when shooting SLog2/3. However, currently few edit applications or grading applications use this metadata to offset the exposure, so S-Log2/3 material may look dark/bright when imported into your edit application and you may need to add a correction to return the exposure to a “normal” level. As the footage is log you should use log corrections to get the very best results. As an alternative you can use a correction LUT to move the exposure up and down like the ones for SLog2 available here, created by cameraman and DP Ben Turley. http://www.turley.tv. Sony’s Raw Viewer software does correctly read the Slog2/3 metadata and will automatically add any required offsets. If shooting raw the majority of grading and editing applications will correctly read the metadata in the raw footage and apply the correct exposure offset, so raw normally looks correctly exposed.

See also this article for more information on EI gain and raw on the F5 and F55.

If shooting raw then you may choose to add the S-Log2/3 LUT to your internal SxS recordings. This will then add the EI-gain to the internal SxS recordings, so they will become brighter/darker as if applying actual gain while only the raw recordings remain at the native ISO. This may be useful if you wish to use the SxS recordings as a proxy file for the edit and would like the proxy files to look similar to the way the final footage will look after grading and correction for the EI offset.

WHAT IF YOU ARE SHOOTING USING HFR (High Frame Rate) AND LUT’S CANT BE USED.

In HFR you can either have LUT’s on for everything including internal recording, or all off, not LUT at all. This is not helpful if your primary recordings are internal SLog.

So if you can’t use the LUT’s you can use the VF High Contrast mode. 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 VF High Contrast Mode acts as a 709(800) LUT for the viewfinder only. So expose at the native ISO, by eye, using normal 709 type levels and your Slog-3 should be pretty close to perfect.

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 have it turned on.

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. Also if the LUT’s are off then you can’t use different EI gains.

CINE-EI SUMMARY:

CineEI allows you to “rate” the camera at different ISO.

You MUST use a LUT for CineEI to work as designed.

A low EI number will result in a brighter exposure which will improve the signal to noise ratio giving a cleaner picture or allow you to see more shadow detail. However you will loose some over exposure headroom.

A high EI number will result in a darker exposure which will improve the over exposure headroom but decrease the under exposure range. The signal to noise ratio is worse so the final picture may end up with more noise.

A 1D LUT will not clip and appear to overexpose as readily as a 3D LOOK when using a low EI, so a 1D LUT may be preferable.

When viewing via a 709 LUT you expose using normal 709 exposure levels. Basically if it looks right in the viewfinder or on the monitor (via the 709 LUT) it almost certainly is right.

When I shoot with my F5 I normally rate the camera as 800EI. I find that 5 stops of over exposure range is plenty for most situations and I prefer the decrease in noise in the final pictures. I rate the F55 similarly at 640EI. But please, test and experiment for yourself.

QUICK GUIDE TO CREATING YOUR OWN LOOK’s (Using DaVinci Resolve).

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 and .cube LUT’s are the most common types of LUT in use today.

First simply shoot some test Slog3 clips at the cameras native ISO. You must use Slog3 if you want to use User 3D LOOK’s in the camera. In addition you should also use the same color space for the test shot as you will when you want to use the LUT. I recommend shooting a variety of clips so that you can asses how the LUT will work in different lighting situations.

Import and grade the clips from the test shoot in Resolve creating the look that you are after for your production or as you wish your footage to appear in the viewfinder of the camera. Then once your happy with the look of the graded clip, right click on the clip in the timeline and “Export LUT”. Resolve will then create and save 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.