Category Archives: PXW-FS5

Why is the white balance limited to 3 presets when using S-Log2, S-Log3 or raw?

This seems to be a source of frustration for many people shooting  raw or using S-Log2 or S-Log3 on a Sony camera. When shooting log and raw you should also be using a matching S-Gamut colour gamut if you want to get the best from the camera and this ties you into one of 3 preset white balances.

With a PXW-FS7, PMW-F5 or F55 it is possible to use custom mode to select a different colour space to mix with S-Log2 or S-Log3 and then have a variable white balance. With the Alpha cameras, PXW cameras such as the FS5 you can choose any Gamut you want in the picture profiles, but I don’t recommend this. For a start, if you don’t use one of the S-Gamuts you will be limited to Rec-709 Gamut, so you won’t be recording  the cameras full colour range. Also in custom mode there are some other things like noise reduction that you really don’t want when shooting S-log2/3 (it can cause banding).

So why is the S-Gamut white balance fixed to the 3 presets for daylight, fluorescent and tungsten? The main reason is to ensure you get the cameras full dynamic range in each colour. White balance is a gain function, it adjusts the gain of the red, green and blue channels so that white objects appear white under differing light sources. So if the light source lacks blue light – making the pictures look excessively warm – you add extra gain to the blue channel to compensate.

But the problem with this is that gain affects dynamic range. When shooting log (or raw) the camera needs to operate the sensor at the optimum gain level to squeeze the highest possible dynamic range from the it. Changing the gain in just one colour channel to shift the white balance could result in a reduction of dynamic range in the channel. This could manifest itself as colours in one channel that clip sooner than the others. This can be really hard to deal with in post production and can show up as things like bright clouds with a colour cast that isn’t in the rest of the picture.

Another potential issue is that because of the way silicon sensors work the blue channel is almost always noisier than the red and green. So you want to keep the gain in the blue channel as low as possible to prevent the pictures getting too noisy. This is particularly important when shooting log as you won’t see your end result until after the images have been graded. So manually shifting the gain of the blue channel in camera to correct the white balance could lead to footage that ends up noisier than you would expect.

So – Sony chose to fix the white balance to 3 carefully tuned presets designed to avoid this situation and maximise the dynamic range. After all, when shooting log or raw it is expected that the footage will be graded anyway, so the white balance will normally be adjusted as part of the post production process.

There are some people that advocate adjusting the FS5’s white balance via the picture profile settings, personally I don’t recommend this or feel that it’s necessary. But yes, you can do this, but just keep a very close eye on your highlights and if you can use monitor with RGB parade to make sure you have equal recording levels for your whites without one colour channel clipping ahead of the others. Also apply a LUT in the monitor that is close to your desired output so that you can keep an eye on the noise levels.

In summary – the white balance is preset to ensure you don’t encounter problems later on. You should be able to fully adjust and fine tune your white balance in post production to a far greater degree than is possible in camera anyway, so don’t worry if the WB is a touch off when shooting.

The only exception to this is the new Sony Venice. Venice has enough dynamic range and enough internal processing power to allow you to make a wide range of white balance adjustments in camera. Hopefully we will see some of this flexibility trickle down to the next generations of lower cost Sony digital cinema cameras.

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PXW-FS5 II Secret Sauce and Venice Colour Science.

At NAB 2018 a very hot topic is the launch of the FS5 II. The FS5 II is an update on the existing FS5 that includes the FS Raw output option and the HFR option as standard. So out of the box this means that this camera will be a great match to an Atomos Inferno to take advantage of the new Apple ProRes Raw codec.

Just like the FS5 the FS5 II can shoot using a range of different gamma curves including Rec-709, HLG, S-Log2  and S-Log3. So  for those more involved projects where image control is paramount you can shoot in log (or raw)  then take the footage into your favourite grading software and create whatever look you wish. You can tweak and tune your skin tones, play with the highlight roll off and create that Hollywood blockbuster look – with both the FS5 and the FS5 II. There is no change to this other than the addition of FS-Raw as standard on the FS5 II.

The big change, is to the cameras default colour science.

FS5II-1-1024x564 PXW-FS5 II Secret Sauce and Venice Colour Science.
New color science from the Sony PXW-FS5 II

Ever since I started shooting on Sony cameras, which was a very long time ago, they have always looked a certain way. If you point a Sony camera at a Rec-709 test chart you will find that the colours are actually quite accurate, the color patches on the chart lining up with the target boxes on a vector scope. All Sony cameras look this way so that if you use several different cameras on the same project they should at least look very similar, even if one of those cameras is a few years old.  But this look and standard was establish many years ago when camera and TV technology was nowhere near as advanced as it is today.

in addition, sometimes accurate isn’t pretty. Television display technology has come a long way in recent years. Digital broadcasting combined with good quality LCD and OLED displays now mean that we are able to see a wider range of colours and a larger dynamic range. Viewers expectations are changing, we all want prettier images.

When Sony launched the high end Venice digital cinema camera a bold step was taken, which was to break away from the standard Sony look and instead develop a new, modern, “pretty” look. A lot of research was done with both cinematographers and viewers trying to figure out what makes a pretty picture. Over several months I’ve watched Pablo, Sony’s colourist at the Digital Motion Picture Center at Pinewood studios develop new LUT’s with this new look for the Venice camera. It hasn’t been easy, but it looks really nice and is quite a departure from that standard Sony look.

The FS5 II includes many aspects of this new look. It isn’t just a change to the colours it is also a change to the default gamma curve that introduces a silky smooth highlight roll off that extends the dynamic range well beyond that normally possible with a conventional Rec-709 gamma curve. A lot of time was spent looking at how this new gamma behaves when shooting people and faces. In particular those troublesome highlights that you get on a nose or cheek that’s catching the light. You know – those pesky highlights that just don’t normally look nice on a video camera.

So as well as rolling off the brightness of these highlights in a smooth way, the color also subtly washes out to prevent the highlight color bloom that can be a video give away. This isn’t easy to do. Any colorist will tell you that getting bright skin tone highlights to look nice is tough. You bring down the brightness and it looks wrong because you loose too much contrast. De-saturate too much and it looks wrong as it just becomes a white blob. Finding the right balance of extended dynamic range with good contrast, plus a pleasing roll-off without a complete white-out is difficult enough to do in a grading suite where you can tweak and tune the settings for each shot. Coming up with a profile that will work over a vast range of shooting scenarios with no adjustment is even tougher. But it looks to me as though the engineers at Sony have really done a very nice job in the FS5 II.

Going forwards from here I would expect to see, or at least like to see, most of Sony’s future cameras have this new colour science. But this is a big step for Sony to break away from decades of one look and every camera looking more or less the same.  But do remember this change is primarily to the default, “standard” gamma look. It does not effect the FS5 II’s log or raw recordings. There is also going to have to be a set of LUT’s to go with this new color science so that those shooting with with a mix of the baked in look and S-log or raw can make all the footage match. In addition users of other S-Log cameras will want to be able to make their cameras match. I see no reason why this won’t be possible via a LUT or set of LUT’s, within the limitations of each cameras sensor technology.

There has been a lot of people that seem unhappy with the FS5 II. I think many people want a Sony Venice for the price of an FS5. Let’s be realistic, that isn’t going to happen. 10 bit recording in UHD would be nice, but that would need higher bit rates to avoid motion artefacts which would then need faster and more expensive media. If you want higher image quality in UHD or 4K DCI do consider an Atomos recorder and the new ProRes Raw codec. The files are barely any bigger than ProRes HQ, but offer 12 bit quality.

Given that the price of the FS5 II is going to be pretty much the same or maybe even a little lower than the regular FS5 (before you even add any options), I am not sure why so many people are complaining. The FS5-II takes a great little camera, makes it even better and costs even less.

 

ProRes Raw and Atomos Inferno and Sumo – BIG deal for the FS5 and FS7!!

proresraw-logo ProRes Raw and Atomos Inferno and Sumo - BIG deal for the FS5 and FS7!!Over the last few days there have been various rumours and posts coming from Apple about how they intend to get back to providing decent support for professional users of their computers. Apple have openly admitted that the Trash Can Mac Pro has thermal problems and as a result has become a dead end design, which is why there haven’t been any big updates to the flagship workstation from Apple. Apple have hinted that new workstations are on the way, although it would seem that we won’t see these until next year perhaps.
Another announcement came out today, a new version of FCP-X is to be released which includes support for a new ProRes codec called ProRes Raw. This is BIG!

PRORES RAW.

Raw recordings can be made from certain cameras that have bayer sensors such as the Sony FS5 and FS7. Recording the raw data from the sensor maximises your post production flexibility and normally offers the best possible image quality from the camera. Currently if you record 4K raw with these cameras using an Atomos Shogun or similar the bit rate will be close to 3Gb/s at 24p. These are huge files and the cDNG format used to record them is difficult and clunky to work with.  As a result most users take the raw output from the camera and transform it to S-Log2 or S-Log3 and record it as 10 bit ProRes on the external recorder. This is a bit of a shame as going from 12 bit linear raw to 10 bit S-log means you are not getting the full benefit of the raw output.

Enter ProRes Raw:  ProRes Raw will allow users to record the cameras raw output at a much reduced bit rate with no significant of quality. There are two versions, ProRes Raw and ProRes Raw HQ. The HQ bit rate is around 1Gb/s at 24fps. This is not significantly bigger than the ProRes HQ (880Mb/s) that most users are using now to record the raw, yet the full benefit of 12 bit linear will be retained. A 1TB SSD will hold around an hour of ProRes Raw, compare that to uncompressed raw where you only get around 20 mins and you can see that this is a big step forwards for users of the FS5 in particular.

ProRes Raw (the non HQ version) is even smaller! The files are smaller than typical ProRes HQ files. This is possible because recording raw is inherently more efficient than recording component video.

It is claimed by Apple that ProRes Raw will play back in real time on MacBook Pro’s and iMacs without any additional rendering or external graphics cards, so it obviously isn’t terribly processor intensive. This is excellent news! Within FCP-X the playback resolution can be decreased to bring improved playback performance in less powerful systems or mutistream playback.

It looks like you will be able to record from a 4K DCI  from an FS5 or FS7 at up to 60fps continuously. This breaks through the previous limits for the Shogun of 30fps. The FS7 will be able to record 2K raw at up to 240fps and the FS5 will be able to record 4K raw at 100 and 120fps for 4 seconds. Other raw cameras are also supported by the Atomos recorders at differing frame sizes and frame rates.

At the moment the only recorders listed as supporting ProRes Raw are the Atomos Shogun Inferno and the Sumo19 and it looks like it will be a free update. In addition the DJI Inspire 2 drone and Zenmuse X7 Super 35mm camera will also support ProRes Raw.

Whether you will be able to use ProRes Raw in other applications such as Resolve or Premiere is unclear at this time. I hope that you can (or at least will be able to in the near future).

SEE: Apple Press Release.

SEE: Apple ProRes Raw White Paper

SEE: ATOMOS ProRes Raw INFO PAGE.

 

 

Sony Cash-Back Offer Ends Soon (Europe).

Camcorder-Accessory-Promotion_home-medium-EN Sony Cash-Back Offer Ends Soon (Europe).Sony are offering up to £220/€250 cash back on accessories purchased with an FS5 and up to £400/€450 cash back on accessories purchased with  FS7 or FS7M2 if you purchase one before the end of March 2018. So there’s only 2 weeks left to take advantage of this offer!

So if your looking at investing in a nice camera kit with perhaps one of the excellent UWP-D radio mic kits that connect directly to the cameras MI shoe or some extra batteries this might be a great way to get some money back from Sony. There are various terms and conditions so please take a look at the promotion page for the full details. Here’s a link to the promotion page.

 

Use the cameras media check to help ensure you don’t get file problems.

Any of the Sony cameras that use SxS or XQD cards include a media check and media restore function that is designed to detect any problems with your recording media or the files stored on that media.
However the media check is only normally performed when you insert a card into the camera, it is not done when you eject a card as the camera never knows when you are about to do that.
So my advice is: When you want to remove the card to offload your footage ensure you have a green light next to the card, this means it should be safe to remove. Pop the card out as you would do normally but then re-insert the card and wait for the light to go from red, back to green. Check the LCD/VF for any messages, if there are no messages, take the card out and do your offload as normal.
 
Why? Every time you put an XQD or SxS card into the camera the card and files stored on it are checked for any signs of any issues. If there is a problem the camera will give you a “Restore Media” warning. If you see this warning always select OK and allow the camera to repair whatever the problem is. If you don’t restore the media and you then make a copy from the card, any copy you make will also be corrupt and the files may be inaccessible.
Once the files have been copied from the card it is no longer possible to restore the media.  If there is a problem with the files on the card, the restore can only be done by the camera, before offload. So this simple check that takes just a few seconds can save a whole world of hurt. I wish there was a media check button you could press to force the check, but there isn’t. However this method works.
It’s also worth knowing that Catalyst Browse and the old Media Browser software performs a data integrity check if you directly attach an SxS card or XQD card to the computer and access the card from the software. If a problem is found you will get a message telling you to return the media to the camera and perform a media restore. But if this is some time after the shoot and you don’t have the camera to hand, this can be impossible. Which is why I like to check my media in the camera by re-inserting it back into the camera so that it gets checked for problems before the end of the shoot.

How does the Panasonic EVA1 stack up against the Sony FS7 and FS5?

This is a question a lot of people are asking. As I’ve mentioned in other recent posts, sensors have reached a point where it’s very difficult to bring out a camera where the image quality will be significantly different from any other on the market for any given price point. Most differences will be in things like codec choices or trading off a bit of extra resolution for sensitivity etc. Other differences will be in the ergonomics, lens mounts and battery systems.

So it’s interesting to see what Keith Mullin over at  Z-Systems thought of the EVA1. Keith knows his stuff and Z-Systems are not tied to any one particular brand.

Overall as expected there isn’t a huge difference in image quality between any of the 3 cameras. The EVA1 seems weaker in low light which is something I would have predicted given the higher pixel count. The dual ISO mode seems not to be anywhere near the same as the really very good dual ISO mode in the Varicam LT.

Why not take a look at the full article and video for yourself. http://zsyst.com/2017/12/panasonic-eva1-first-look/

 

FS5 Eclipse and 3D Northern Lights by Jean Mouette and Thierry Legault.

Here is something a little different.

I few years ago I was privileged to have Jean Mouettee and Thierry Legault join me on one of my Northern Lights tours. They were along to shoot the Aurora on an FS100 (it might have been an FS700) in real time. Sadly we didn’t have the best of Auroras on that particular trip. Theirry is famous for his amazing images of the Sun with the International Space Station passing in front of it.

iss_atlantis_transit2_2010 FS5 Eclipse and 3D Northern Lights by Jean Mouette and Thierry Legault.
Amazing image by Thierry Legault of the ISS passing in front of the Sun.

Well the two of them have been very busy. Working with some special dual A7s camera rigs recording on to a pair of Atomos Shoguns, they have been up in Norway shooting the Northern Lights in 3D. You can read more about their exploits and find out how they did it here: https://www.swsc-journal.org/articles/swsc/abs/2017/01/swsc170015/swsc170015.html

To be able to “see” the Aurora in 3D they needed to place the camera rigs over 6km apart. I did try to take some 3D time-lapse of the Aurora a few years back with cameras 3Km apart, but that was timelapse and I was thwarted by low cloud. Jean and Thierry have gone one better and filmed the Aurora not only in 3D but also in real time. That’s no mean feat!

20170218_233041_rec FS5 Eclipse and 3D Northern Lights by Jean Mouette and Thierry Legault.
One of the two A7s camera rigs used for the real time 3D Aurora project. The next stage will use 4 cameras in each rig for whole sky coverage.

If you want to see the 3D movies take a look at this page: http://www.iap.fr/science/diffusion/aurora3d/aurora3d.html

I’d love to see these projected in a planetarium or other dome venue in 3D. It would be quite an experience.

Jean was also in the US for the total Eclipse in August. He shot the eclipse using an FS5 recording 12 bit raw on a Atomos Shogun. He’s put together a short film of his experience and it really captures the excitement of the event as well as some really spectacular images of the moon moving across the face of the sun. I really shows what a versatile camera the FS5 is.

If you want a chance to see the Northern Lights for yourself why not join me next year for one of my rather special trips to Norway. I still have some spaces. http://www.xdcam-user.com/northern-lights-expeditions-to-norway/

Why are Sony’s ISO’s different between standard gammas and log?

With Sony’s log capable cameras (and most other manufacturers) when you switch between the standard gamma curves and log gamma there is a change in the cameras ISO rating. For example the FS7 is rated at 800 ISO in rec709 but rated at 2000 ISO in log. Why does this change occur and how does it effect the pictures you shoot?

As 709 etc has a limited DR (between around 6 and 10 stops depending on the knee settings) while the sensor itself has a 14 stop range, you only need to take a small part of the sensors full range to produce that smaller range 709 or hypergamma image. That gives the camera manufacturer some freedom to pick the sweetest part of the sensors range. his also gives some leeway as to where you place the base ISO.

I suspect Sony chose 800 ISO for the FS7 and F5 etc as that’s the sensors sweet spot, I certainly don’t think it was an accidental choice.

What is ISO on an electronic camera? ISO is the equivalent sensitivity rating. It isn’t a measure of the cameras actual sensitivity, it is the ISO rating you need to enter into a light meter if you were using an external light meter to get the correct exposure settings. It is the equivalent sensitivity. Remember we can’t change the sensor in these cameras so we can’t actually change the cameras real sensitivity, all we can do is use different amounts of gain or signal amplification to make the pictures brighter or darker.

When you go switch the camera to log you have no choice other than to take everything the sensor offers. It’s a 14 stop sensor and if you want to record 14 stops, then you have to take 100% of the sensors output. The camera manufacturer then chooses what they believe is the best exposure mid point point where they feel there is an acceptable compromise between noise, highlight and lowlight response. From that the manufacture will get an ISO equivalent exposure rating.

If you have an F5, FS7 or other Sony log camera, look at what happens when you switch from rec709 to S-Log2 but you keep your exposure constant.

Middle grey stays more or less where it is, the highlights come down. White will drop from 90% to around 73%. But the ISO rating given by the camera increases from 800ISO to 2000ISO. This increased ISO number implies that the sensor became more sensitive – This is not the case and a little missleading. If you set the camera up to display gain in dB and switch between rec709 (std gamma) and S-Log the camera stays at 0dB, this should be telling you that there is no change to the cameras gain, no change to it’s sensitivity. Yet the ISO rating changes – why?

The only reason the ISO number increases is to force us to underexpose the sensor by 1.3 stops (relative to standard gammas such as rec709 and almost every other gamma) so we can squeeze a bit more out of the highlights. If you were using an external light meter to set your exposure if you change the ISO setting on the light meter from 800 ISO to 2000 ISO  the light meter will tell you to close the aperture by 1.3 stops. So that’s what we do on the camera, we close the aperture down a bit to gain some extra highlight range.

But all this comes at the expense of the shadows and mid range. Because you are putting less light on the sensor if you use 2000 ISO as your base setting the shadows and mids are now not as good as they would be  in 709 or with the other standard gammas.

This is part of the reason why I recommend that you shoot with log between 1 and 2 stops brighter than the base levels given by Sony. If you shoot 1 stop brighter that is the equivalent to shooting at 1000 ISO and this is closer to the 800 ISO that Sony rate the camera at in standard gamma.  Shooting that bit brighter gives you a much better mid range that grades much better.

 

Why is exposing log brightly beneficial?

I have been asked whether you should still expose log a bit brighter than the recommended base levels on the Sony PXW-FS5 now that Sony have released new firmware that gives it a slightly lower base ISO. In this article I take a look at why it might be a good idea to expose log (with any camera) a bit brighter than perhaps the manufacturer recommends.

There are a couple of reasons to expose log nice and bright, not just noise. Exposing log brighter makes no difference to the dynamic range. That’s determined by the sensor and the gain point at which the sensor is working. You want the camera to be at it’s native sensitivity or 0dB gain to get that maximum dynamic range.

Exposing brighter or darker doesn’t change the dynamic range but it does move the mid point of the exposure range up and down.  Exposing brighter increases the under exposure range but decreases the over exposure range. Exposing darker decreases the under exposure range but increases the over exposure range.

Something that’s important when thinking about dynamic range and big dynamic ranges in particular is that dynamic range isn’t just about the highlights it’s also about the shadows, it isn’t just over exposure, it’s under exposure too, it’s RANGE.

So why is a little bit of extra light often beneficial? You might call it “over exposure” but that’s not a term I like to use as it implies “too much exposure”. I prefer to use “brighter exposure”.

It’s actually quite simple, it’s about putting a bit more light on to the sensor. Most sensors perform better when you put a little extra light on them. One thing you can be absolutely sure of – if you don’t put enough light on the sensor you won’t get the best pictures.

Slide01 Why is exposing log brightly beneficial?

Put more light on to the sensor and the shadows come up out of the sensors noise floor. So you will see further into the shadows. I’ve had people comment that “why would I ever want to use the shadows, they are always noisy and grainy”? But that’s the whole point – expose a bit brighter and the shadows will be much less noisy, they will come up out of the noise. Expose 1 stop brighter and you halve the shadow noise (for the same shadows at the previous exposure).  Shadows are are only ever noise ridden if you have under exposed them.

This is particularly relevant in controlled lighting. Say you light a scene for 9 stops. So you have 9 stops of dynamic range but a 14 stop sensor. Open up the aperture, put more light on the sensor, you get a better signal to noise ratio, less noisy shadows but no compromise of any type to the highlights because if the scene is 9 stops and you have 14 to play with, you can bring the exposure up by a couple of stops comfortably within the 14 stop capture range.

S-log-levels Why is exposing log brightly beneficial?
Chart showing S-Log2 and S-Log3 plotted against f-stops and code values. Note how little data there is for each of the darker stops, the best data is above middle grey. Note that current sensor only go to +6 stops ove middle grey so S-Log2 and S-Log record to different peak levels.

Look at the above diagram of Sony’s S-Log2 and S-Log3 curves. The vertical 0 line in the middle is middle grey. Note how above middle grey the log curves are more or less straight lines. That’s because above the nominal middle grey exposure level each stop is recorded with the same amount of data, this you get a straight line when you plot the curve against exposure stops. So that means that it makes very little difference where you expose the brighter parts of the image. Expose skin tones at stop + 1 or stop +3 and they will have a very similar amount of code values (I’m not considering the way dynamic range expands in the scene you shoot as you increase the light in the scene in this discussion). So it makes little difference whether you expose those skin tones at stop +1 or +3, after grading they will look the same.

Looking at the S-Log curve plots again note what happens below the “0” middle grey line. The curves roll off into the shadows. Each stop you go down has less data than the one before, roughly half as much. This mimics the way the light in a real scene behaves, but it also means there is less data for each stop. This is one of the key reasons why you never, ever want to be under exposed as if you are underexposed you mid range ends up in this roll off and will lack data making it not only noisy but also hard to grade as it will lack contrast and tonal information.

Open up by 1 additional stop and each of those darker stops is raised higher up the recording curve by one stop and every stop that was previously below middle grey doubles the amount of tonal values compared to before, so that’s 8 stops that will have 2x more data than before. This gives you a nice fat (lots of data) mid range that grades much better, not just because it has less noise but because you have a lot more data where you really need it – in the mid range.

Note: Skin tones can cover a wide exposure range, but typically the mid point is around 1 to 1.5 stops above middle grey. In a high contrast lighting situation skin tones will start just under middle grey and extend to about 2 stops over. If you accidentally under expose by 1 stop or perhaps don’t have enough light for the correct exposure you will seriously degrade the quality of your skin tones as half of your skin tones will be well below middle grey and in the data roll-off.

Now of course you do have to remember that if your scene does have a very large dynamic range opening up an extra stop might mean that some of the very brightest highlights might end up clipped. But I’d happily give up a couple of specular highlights for a richer more detailed mid range because when it comes to highlights – A: you can’t show them properly anyway because we don’t have 14 stop TV screens and B: because highlights are the least important part of our visual range.

A further consideration when we think about the highlights is that with log there is no highlight roll-off. Most conventional gamma curves incorporate a highlight roll-off to help increase the highlight range. These traditional highlight roll-offs reduce the contrast in the highlights as the levels are squeezed together and as a result the highlights contain very little tonal information. So even after grading they never look good, no matter what you do. But log has no highlight roll-off. So even the very brightest stop, the one right on the edge of clipping contains just as much tonal information as each of the other brighter than middle grey stops. As a result there is an amazingly large amount of detail than can be pulled out of these very bright stops, much more than you would ever be able to pull from most conventional gammas.

Compare log to standard gammas for a moment. Log has a shadow roll-off but no highlight roll-off. Most standard gammas have a strong highlight roll-off. Log is the opposite of standard gammas. With standard gammas, because of the highlight roll-off, we normally avoid over exposure because it doesn’t look good. With Log we need to avoid under exposure because of the shadow roll-off, it is the opposite to shooting with standard gammas.

As a result I strongly recommend you never, ever under expose log. I normally like to shoot log between 1 and 2 stops brighter than the manufacturers base recommendation.

Next week: Why is a Sony camera like the FS7,F5 800 ISO with standard gamma but 2000 ISO in log and how does that impact the image?

 

The Pro’s and Con’s of 12 bit linear raw or recording raw to S-Log.

UPDATE: JUST TO BE CLEAR, THERE IS NOTHING WRONG WITH SONY’S 12 BIT LINEAR RAW. BUT YOU REALLY SHOULD BE AWARE OF IT’S LIMITATIONS COMPARED TO 16 BIT RAW OR POSSIBLY EVEN 10 BIT LOG.

This came up in the comments today and it’s something that I get asked about quite a lot.

Sony’s high end cameras, designed for raw – F5, F55, F65 all use 16 bit linear data. This linear data contains an impressively large amount of picture information across the entire range from the darkest shadows to the brightest highlights. This huge amount of data gives footage that can be pushed and pulled in post all over the place. 16 bit raw gives you 65,536 discreet values.

The FS7 and FS5 use 12 bit linear raw. 12 bit data gives you 4096 discreet values, 1/15th of the values, a small fraction of what 16 bit has. This presents a problem as to record 14 stops with linear data you need more than 12 bits.

Not Enough Code Values.

There just aren’t enough code values with only 12 bits (which is why no one else does it). So Sony do some clever math to make it workable. This reduces the amount of tonal steps in in the shadows.  On it’s own this isn’t a huge problem, just make sure you expose brightly to avoid trying to pull to much info out of the shadows and definitely don’t use it for low light. On high key scenes 12 bit raw is very nice indeed, this is where it excels. On low key scenes it can appear very grainy, noisy and shadows often look coarse and lack smooth textures. Expose nice and bright and you will get great highly gradable footage. Expose dark and you will have big problems.

Transcoding can add to the problems.

Where you really can run into problems is if you take 12 bit raw (with it’s reduced shadow data) and convert that to 10 bit log (which has reduced highlight data relative to the scene you are shooting).

What you end up with is 10 bit log with reduced shadow data compared to a straight 10 bit log recording. If you compare the direct 10 bit S-log from an FS7 (or F5/F55) to 10 bit S-log derived from 12 bit raw from an FS5, the FS7 internal 10 bit log picture will have a little more shadow information while the highlights from both will be similar. So the direct internal 10 bit log recording from an FS7 will typically be a little better in the shadows than any log created from the 12  bit raw and there will little, if any, highlight benefit.  It’s a little different for the FS5 as in UHD this is limited to 8 bit, so the raw, converted to log from the FS5 will have better highlight data, but still be a touch weak in the darkest shadow areas.  Overall  10bit log derived from 12 bit linear will be better than 8 bit log, but not better than 10 bit log.

If 4K S-Log is really important to you – get an FS7, F5 or F55.

So I’d much rather have an FS7 (F5 or F55) if I want to shoot UHD or 4K S-log. That’s what these cameras are designed for. But, if you only have an FS5, the raw to log workflow will outperform the limited 8 bit UHD log, so it is still definitely beneficial for FS5 owners to shoot raw and convert it to 10 bit S-Log with an external recorder. But better still record raw, then you really will have a better image.

Raw with the FS7.

On the FS7 the benefits of recording 12 bit raw over 10 bit S-Log are less clear. For bright, well exposed scenes the 12 bit raw will  have a definite  edge. But the files you will create if using an Atomos or Convergent Design recorder are huge compared to the compressed internal recording and that needs to be considered. For low key or under exposed scenes there is no benefit to shooting 12 bit raw you will get nothing extra.

On the FS7 it is not a good idea to take the 12 bit raw output and record it as 10 bit S-Log on an external recorder. While you may have a less compressed codec, you will be compromising the shadows compared to the cameras own internally generated 10 bit log recordings.  In most cases you would be better off simply taking the HDMI output and recording that as it avoids the 12 bit linear shadow bottleneck.

Again though – exposing nice and bright is the key to a good result. Get the data up into the brighter parts of the recording and the raw can be fantastic.

Internal and external log brightness shifts.

When you record S-Log internally on the Sony cameras the recordings use full range data levels to maximise the codec performance. You can use data range (which exceeds the normal video range) as it is assumed the data will be graded and as part of this process restored to video range data for viewing. However when recording on an external recorder the recordings sometimes use full video range rather than data range or if it’s data range don’t have the right metadata. This shouldn’t be a huge problem if the grading software behaves itself and treats each type of content correctly, shifting each to one unified range, but sadly this is rarely the case (especially with Adobe). So not only do the internal and externally recorded images come out with different brightness and contrast, but also LUT’s designed for one don’t work the same with the other. It’s a bit of a minefield to be honest and one of the reason why I prefer to always grade with dedicated grading software like resolve which handles the levels conversions properly (most of the time at least).