Tag Archives: raw

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/

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Beware Exposing To The Right With Log.

That may seem like quite a sensational headline – beware exposing to the right with log – but let me explain.

First of all, I’m not saying you can’t or shouldn’t expose to the right, all I am saying is beware – understand the implications.

First of all what is normally meant by exposing to the right? Well it’s a term that comes from the world of photography where you would use the cameras histogram to measure the exposure levels. Exposing to the right would normally mean setting the shutter speed and aperture so that the levels shown on the histogram are as far to the right as you can get them without going beyond the right side of the histogram. This would ensure a nice bright exposure with lots of light falling on the sensor, something that is normally highly desirable as you get a nice low noise picture once you have adjusted and processed it in your photo editing software.

You can expose to the right with a video camera too. However when shooting with Rec-709 or conventional gammas this can often result in nasty looking highlights thanks to the default knee settings, so it’s not normally a good idea for 709 and standard gammas.

With log or raw as there is no highlight roll off you can expose to the right and it should give you a nice bright exposure… or will it?????

The problem with exposing to the right is that you are exposing for the highlights in the scene. If shooting a low contrast or low dynamic range scene this isn’t going to cause any problems as exposing to the right will mean that everything in the scene is nice and bright.

But if shooting a high dynamic range scene, say an outdoor scene with bright clouds in the sky but large areas of shadow, the exposure will be optimised for the highlights. The mid range and shadows may end up too dark. On a sunny day if shooting a person with their back to the sun the sky could easily be 6 or 7 stops brighter than the skin tones. If you expose for the sky/highlights the skin tones will be 1 or 2 stops darker than the basic exposure level recommended for most  log curves.

(S-log2/3 has 14 stops. At the base exposure you have 6 stops above middle grey and 8 below. Skin tones are normally between 1 and 2 stops above middle grey. So if the sky/highlights are 6 stops above the skin tones, then exposing for the highlights will put the skin tones where middle grey should be, which is 1 stop under exposed and 2 stops below where I would normally like to see skin tones when shooting with log or raw).

The first thing a viewer will notice when they look at a scene with faces or people will be the skin tones. If these have been under exposed they will be grainy and less than ideal. The viewer will notice noise and grain and poor shadows long before they look at the brightest highlights. Shooting log and protecting the highlights or exposing to the right will often compromise the all important mid tones because you are exposing for the highlights, not the midrange. In addition exposing for highlights with a high dynamic range scene can often push the shadows down in level and they will end up noisy and grainy. The biggest issue with exposing to the right is that it’s extremely difficult to estimate how many stops there are between your mid tones and the highlights, so you never know quite where your mid tones are falling.

(Midtones – generally a white piece of paper or a 90% reflectivity white card would be considered to be the top end of the mid tones. Go down about 2.5 stops from white and you hit middle grey  (18% grey card). This range between middle grey and white is where skin tones, plants, most animals etc will be and it probably the most important part of most images).

An important consideration with log and raw is that there is no highlight roll off. Standard gammas (with the default knee found on almost every camera) , cinegammas, hypergammas etc all roll off the highlights. That is to say that as you approach the peak recording level the contrast is reduced as the highlights are squeezed together to try to extend the dynamic range. This reduction in contrast means that it is very difficult, if not impossible, to recover any nice, useable picture information out of anything close to the peak recording level. As a result with conventional gammas we tend to avoid over exposure at all costs as it looks nasty. This highlight roll off is one of the things that gives video the video look.

Log and raw don’t have this same kind of highlight roll off. The image gets brighter and brighter until it clips. With log the stop immediately below clipping contains just as much picture information as any other stop brighter than middle grey. With linear raw the stop just below clipping has more information than any other stop. As a result in post production there is a very large amount of data that can be pulled out of these highlights, even if they are a little clipped! So don’t worry about a few clipped highlights when shooting log. The other thing to remember is there is no TV or monitor that can show these highlights as they really are, so they will never look perfect anyway.

Another thing that happens when exposing to the right is that grading becomes harder than it needs to be. Because the separation between the mid tones and highlights will vary greatly depending on things like whether you are shooting into or away from the sun, when you expose to the right you mid tone brightness will be up and down all over the place. So in post production as well as adding the look that you want to your footage, you are also going to have to spend a lot of time matching the mid range exposure to balance skin tones etc from shot to shot.

Rather than exposing to the right what I recommend is exposing for the mid range. After all this is the important part of the image. To do this you need to use a diffuse reflective shade. The most commonly used shades are a 90% white card and/or an 18% reflectivity grey card – middle grey. Get the mid range right and in most cases the highlights will take care of themselves. Getting the mid range right might mean exposing the mid range  brighter than the recommended levels. But it’s the mid range we need to measure, not the highlights, this is the important part of the image.

90% white is an incredibly important level in the world of film and video. A typical piece of office paper reflects about 92-94% of the light falling on it. Office paper often uses brighteners and special chemicals to make it look bright and white. This white is the brightest diffuse surface you will likely ever see.  Anything brighter than this is normally going to be an actual source of light. The sky perhaps or a direct bounced reflection off a shiny, reflective surface such as the bodywork of a car. So anything brighter than 90% white would normally be considered to be a highlight and to us humans, highlights are visually less important than the mid range. This is why the knee on most video cameras kicks in at around 90%. Anything brighter than 90% is a highlight so the knee only effects highlights and leaves the all important mid range alone.

Middle grey is also very important because it’s a shade of grey that to most people looks to be half way between black and white. Skin tones fall roughly half way between middle grey and white. In addition if you average all the brightness levels within a typical scene the end result is typically very close to middle grey.  Light meters are calibrated to middle grey. The relationship between middle grey and white is fixed. White reflects 90%, middle grey 18%, no matter how bright the actual light source. So whether you are indoors, outside. Whether it’s sunny or overcast, white and middle grey will always be close to 2.5 stops apart. They are extremely useful fixed reference levels.

There are many ways to measure the brightness of a white or grey card. My preferred method is with a waveform display. But you could also use zebras (use a narrow zebra window if you can).  You can also use false colour. Unfortunately it’s very difficult to use a histogram to measure the brightness of a specific target. The histogram is a great measuring tool for photography, but less than ideal for video. If you can’t get a white/grey card out in front of the camera you could consider using a light meter. It’s also worth noting that skin tones sit just a little over half way between middle grey and white, so if you have no other reference you could simply place your skin tones a touch brighter than half way between the values you are targetting for middle grey and white.

Just to be clear: I do still recommend exposing Sony’s S-log2, S-log3 and raw between 1 and 2 stops brighter than the Sony base levels. But the key take-away is that it’s the mid range you need to measure and expose at this level. Exposing to the right using a histogram or waveform and just looking at the peaks and brightest parts of the image does not tell you what is happening in he mid range. Measure the mid range, not the peak brightness.

 

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 picture will have a little more shadow information while the highlights from both will be similar. So the 10 bit direct log recording from an FS7 will typically be a little better than the 12  bit raw derived log from an FS5 in the shadows (but the raw derived 10bit log will always be better than 8 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).

What’s the difference between raw and S-Log ProRes – Re: FS5 raw output.

This is a question that comes up a lot.

Raw is the unprocessed (or minimally processed) data direct from the sensor. It is just the brightness value for each of the pixels, it is not a color image, but we know which color filter is above each pixel, so we are able to work out the color later. In the computer you take that raw data and convert it into a conventional color video signal defining the gamma curve and colorspace in the computer.  This gives you the freedom to choose the gamma and colorspace after the shoot and retains as much of the original sensor information as possible.Of course the captured dynamic and color range is determined by the capabilities of the sensor and we can’t magically get more than the sensor can “see”. The quality of the final image is also dependant on the quality of the debayer process in the computer, but as you have the raw data you can always go back and re-encode the footage with a better quality encoder at a later date. Raw can be compressed or uncompressed. Sony’s 12 bit FS-raw when recorded on an Odyssey or Atomos recorder is normally uncompressed so there are no additional artefacts from compression, but the files are large. The 16 bit raw from a Sony F5 or F55 when recorded on an R5 or R7 is made about 3x smaller through a proprietary algorithm.

ProRes is a conventional compressed color video format. So a ProRes file will already have a pre-determined gamma curve and color space, this is set in the camera through a picture profile, scene file or other similar settings at the time of shooting. The quality of the ProRes file is dependant on the quality of the encoder in the camera or recorder at the time of recording, so there is no way to go back and improve on this or change the gamma/colorspace later. In addition ProRes, like most commonly used codecs is a lossy compressed format, so some (minimal) picture information may be lost in the encoding process and artefacts (again minimal) are added to the image. These cannot easily be removed later, however they should not normally present any serious problems.

It’s important to understand that there are many different types of raw and many different types of ProRes and not all are equal. The FS-raw from the FS5/FS7 is 12 bit linear and 12 bit’s are not really enough for the best possible quality from a 14 stop camera (there are not enough code values so floating point math and/or data rounding has to take place and this effects the shadows and low key areas of the image). You really need 16 bit data for 14 stops of dynamic range with linear raw, so if you are really serious about raw you may want to consider a Sony F5 or F55. ProRes is a pretty decent codec, especially if you use ProResHQ and 10 bit log approaches the quality of 12 bit linear raw but without the huge file sizes.  Incidentally there is very little to be gained by going to ProRes 444 when recording the 12 bit raw from an FS5/FS7, you’ll just have bigger files and less record time.

Taking the 12 bit raw from an FS5 and converting it to ProRes in an external recorder has potential problems of it’s own. The quality of the final file will be dependant on the quality of the debayer and encoding process in the recorder, so there may be differences in the end result from different recorders. In addition you have to add a gamma curve at this point so you must be careful to choose the correct gamma curve to minimise concatenation where you add the imperfections of 12 bit linear to the imperfections of the 10 bit encoded file (S-Log2 appears to be the best fit to Sony’s 12 bit linear raw).

Despite the limitations of 12 bit linear, it is normally a noticeable improvement over the FS5’s 8 bit internal UHD recordings, but less of a step up from the 10 bit XAVC that an FS7 can record internally. What it won’t do is allow you to capture anything extra. It won’t improve the dynamic range, won’t give you more color and won’t enhance the low light performance (if anything there will be a slight increase in shadow noise and it may be slightly inferior in under exposed shots). You will have the same dynamic and color range, but recorded with more “bits” (code values to be precise). Linear raw excels at capturing highlight information and what you will find is that compared to log there will be more textures in highlights and brighter parts of your captured scenes. This will become more and more important as HDR screens are better able to show highlights correctly. Current standard dynamic range displays don’t show highlights well, so often the extra highlight data in raw is of little benefit over log. But that’s going to change in the next few years so linear recording with it’s extra highlight information will become more and more important.

Raw and the PXW-FS5

This isn’t a “how to” guide. There are many different recorders that can be used to record raw from the FS5 and each would need it’s own user guide. This is an overview of what raw is and how raw recording works to help those that are a bit confused, or not getting the best results.

First of all – you need to have the raw upgrade installed on the FS5 and it must be set to output raw. Then you need a suitable raw recorder. Just taking the regular SDI or HDMI output and recording it on an external recorder is not raw.

Raw is raw data direct from the cameras sensor with very little image processing. It isn’t even a color image, it won’t become color until some external processing, often called “De-Bayer” is done to convert the raw data to a color image.

For raw to work correctly the camera has to be set up just right. On the FS5 you should use Picture Profile 7. Don’t try and use any other profile, don’t try and shoot without a profile. You must use Picture Profile 7 at it’s factory default settings. In addition don’t add any gain or change the ISO from 3200 (2000 ISO from version 4.02 firmware). Even if the scene is a dark one, adding gain will not help and it may in fact degrade the recorded image.

White balance is set using the appropriate SGamut + color temperature preset chosen from within Picture Profile 7, there are only 3 to choose from for S-Gamut, but with a raw workflow you will normally fine tune the white balance in post. No other color matrix or white balance method should be used. Trying to white balance any other way may result in the sensor data being skewed or shifted in a way that makes it hard to deal with later on.

All of the above is done to get the best possible, full dynamic range data off the sensor and out of the camera.

If you are viewing the S-Log2 (ie don’t have viewfinder gamma assist enabled) then the exposure level that Sony recommend is to have a white card at 60%. So consider setting the zebras to 60%. Don’t worry that this may look a bit dark or appear to be a low level, but that’s the level you should start with… More about exposure later on.

This raw data is then passed down the SDI cable to the external recorder. The external recorder will then process it, turn it into a color signal (de-bayer) and add a gamma curve so that it can be viewed on the recorders screen. Exactly what it will look like on the monitor screen will depend on how the recorder is set up. IF the recorder is set to show S-Log2, then the recorders screen and the FS5’s LCD should look similar. However you might find that it looks very different to what you are seeing on the FS5’s LCD screen. This is not unexpected. If the recorder is setup to convert the raw to Rec-709 for display then the image on the recorder will be brighter and show more contrast, in fact it should look “normal”.

Under the surface however, the external raw recorder is going to be doing one of two things (normally at least). It’s either going to be recording the raw data coming from the camera as it is, in other words as raw. Or it will be converting the raw data to S-Log2 and recording it as a conventional ProRes or DNxHR video file. Either way when you bring this footage in to post production it will normally appear as a flat, low contrast S-Log2 image rather than a bright, contrasty rec-709 image. So understand that the footage will normally need to be graded or have some other changes made to it to look nice.

Recording the actual raw data will give you the best possible information that you can get from the FS5 to work with in post production. The downside is that the files will be huge and will take a fair amount of processing power to work with. Recording a ProRes or DNxHR video file with S-Log2 gamma is second best. You are throwing away a bit of image quality (going from 12 bit linear down to 10 bit log) but the files should still be superior to the 8 bit UHD internal recordings or even an external recording done via the HDMI which is also limited to 8 bit in UHD.

Most raw recorders have the ability to add a LUT – Look Up Table – to the image viewed on the screen. The purpose of the LUT is to convert the S-Log2/raw to a conventional gamma such as Rec-709 so that the picture looks normal. If you are using a LUT then the normal way to do things is to view the normal looking picture on the recorders screen while the recorder continues to record S-Log2 or raw. This is useful as the image on the screen looks normal so it is easier to judge exposure. With a 709 LUT you would expose the picture so that the image on the recorders screen looks as bright as normal, skin tones would be the usual 70% (ish) and white would be 90%.

There is a further option and that is to “bake in the LUT”. This means that instead of just using the LUT to help with monitoring and exposure you actually record the image that you see on the recorders screen. This might be useful if you don’t have any time for grading, but… and it’s a big BUT…. you are now no longer recording S-log2 or raw. You will no longer have the post production grading flexibility that raw or S-Log2 provide and for me at least this really does defeat the whole point of recording raw.

Exposure: Raw will not help you in low light. Raw needs to be exposed brightly (there are some data limitations in the shadows with 12 bit linear raw compared to 16 bit raw and possibly even 10 bit log). If viewing S-Log2 then Sony’s recommendation is to have a white card or white piece of paper at 60%. I consider that to be the absolute minimum level you can get away with. The best results will normally be achieved if you can expose that white card or piece of paper at around 70% to 75% (when looking at an S-Log2 image). Skin tones would be around 55%. If you expose like this you may need to use a different LUT on the recorder to ensure the picture doesn’t look over exposed on the recorders monitor screen. Most of the recorders include LUT’s that have offsets for brighter exposures to allow for this. Then in post production you will also want a LUT with an exposure offset to apply to the S-Log2 recordings. You can use the search function (top right) to find my free LUT sets and download them. Exposing that bit brighter helps get around the shadow data limitations of 12 bit linear raw and pushes the image up into the highlights where there is more data.

SEE ALSO: https://www.sony.co.uk/pro/article/broadcast-products-FS5-raw-shooting-tips

 

Not all raw is created equal. Log may be better

This keeps cropping up time and time again.

Unfortunately every now and again a new term or buzzword comes along that gets taken as a holy grail term. Two that come to mind right now are log and raw. Neither log, nor raw, are magic bullet solutions that guarantee the best performance. Used incorrectly or inappropriately both can result in inferior results. In addition there are many flavours of log and raw each with very different performance ranges.

A particular point in case is the 12 bit raw available from several of Sony’s mid range large sensor cameras, the FS700, FS7 and FS5.

Raw can be either log or linear. This particular flavour of raw is encoded using linear data.  If it is linear then each successively brighter stop of exposure should be recorded with twice as many code values or shades as the previous stop. This accurately replicates the change in the light in the scene you are shooting.  If you make the scene twice as bright, you need to record it with twice as much data. Every time you go up a stop in exposure you are doubling the light in the scene. 12 bit linear raw is actually very rare, especially from a camera with a high dynamic range. To my knowledge, Sony are the only company that offer 14 stops of dynamic range using 12 bit linear data.

There’s actually a very good reason for this: Strictly speaking, it’s impossible! Here’s why: For each stop we go up in exposure we need twice as many code values. With 12 bit data there are a maximum of 4096 code values, this is not enough to record 14 stops.

If stop 1 uses 1 code value, stop 2 will use 2, stop 3 will use 4, stop 4 will use 8 and so on.

STOP:  CODE VALUES:  TOTAL CODE VALUES REQUIRED.

+1          1                                   1
+2          2                                   3
+3          4                                   8
+4          8                                   16
+5          16                                32
+6          32                                64
+7          64                                128
+8          128                             256 Middle Grey
+9          256                             512
+10       512                             1,024
+11       1,024                          2,048
+12       2,048                         4,096
+13       4,096                         8,192
+14       8,192                         16,384

As you can see from the above if we only have 12 bit data and as a result 4096 code values to play with, we can only record an absolute maximum of 12 stops of dynamic range using linear data. To get even 12 stops we must record the first couple of stops with an extremely small amount of tonal information. This is why most 14 stop raw cameras use 16 bit data for linear or use log encoded raw data for 12 bit, where each stop above middle grey (around stop +8) is recorded with the same amount of data.

So how are Sony doing it on the FS5, FS7 etc? I suspect (I’m pretty damn certain in fact) that Sony use something called floating point math. In essence what they do is take the linear data coming off the sensor and round the values recorded to the nearest 4 or 8. So, stop +14 is now only recorded with 2,048 values, stop +13 with 512 values etc. This is fine for the brighter stops where there are hundreds or even thousands of values, it has no significant impact on the brighter parts of the final image. But in the darker parts of the image it does have an impact as for example stop +5 which starts off with 16 values ends up only being recorded with 4 values and each stop below this only has 1 or two discreet levels. This results in blocky and often noisy looking shadow areas – a common complaint with 12 bit linear raw. I don’t know for a fact that this is what they are doing. But if you look at what they need to do, the options available and you look at the end results for 12 bit raw, this certainly appears to be the case.

Meanwhile a camera like the FS7 which can record 10 bit log will retain the full data range in the shadows because if you use log encoding, the brighter stops are each recorded with the same amount of data. With S-Log2 and 10 bit XAVC-I the FS7 uses approx 650 code values to record the 6 brightest stops in it’s capture range reserving approx 250 code values for the 8 darkest stops. Compare this to the linear example above and in fact what you will see is that 10 bit S-Log2 has as much data as you would expect to find in a straight 16 bit linear recording below middle grey (S-Log 3 actually reserves slightly more data for the shadows). BUT that’s for 16 bit. Sony’s 12 bit raw is squeezing 14 stops into what should be an impossibly small number of code values, so in practice what I have found  is that 10 bit S-log has noticeably more data in the shadows than 12 bit raw.

In the highlights 12 bit linear raw will have more data than 10 bit S-log2 and S-Log3 and this is borne out in practice where a brightly exposed raw image will give amazing results with beautiful highlights and mid range. But if your 12 bit raw is dark or underexposed it is not going to perform as well as you might expect. For dark and low key scenes 10 bit S-Log is most likely going to give a noticeably better image. (Note: 8 bit S-log2/3 as you would have from an FS5 in UHD only has a quarter of the data that 10 bit has. The FS5 records the first 8 stops in  8 bit S-log 2 with approx 64 code values, S-Log3 is only marginally better at approx 80 code values. 12 bit linear outperforms 8 bit log across the entire range).

Sony’s F5 and F55 cameras record to the R5 and R7 recorders using 16 bit linear data. 16 bit data is enough for 14 stops. But I believe that Sony still use floating point math for 16 bit recording. This time instead of using the floating point math to make room for an otherwise impossible dynamic range they use it to take a little bit of data from the brightest stop to give extra code values in the shadows. When you have 16,384 code values to play with you can afford to do that. This then adds a lot of extra tonal values and shades to the shadows compared to 10 bit log and as a result 16 bit linear raw will outperform 10 bit log across the entire exposure range by a fairly large margin.

So there you have it.  I know it’s hugely confusing sometimes. Not all types of raw are created equal. It’s really important to understand this stuff if you’re buying a camera. Just because it has raw it doesn’t necessarily mean an automatic improvement in image quality in every shooting situation. Log can be just as good or possibly even better in some situations, raw better in others. There are reasons why cameras like the F5/R5 cost more than a FS5/Shogun/Odyssey.

What is XOCN? Why is it so good, why do we need it?

This time last year I was just starting to earn about a new codec from Sony called XOCN (eXtended Original Camera Negative). XOCN is currently only available with the Sony F5/F55 and the new AXS-R7 raw recorder. Sony’s original R5 raw recorder takes 16 bit sensor data and applies a very mild amount of compression before recording the sensor data as linear raw. I have never seen any compression artefacts when using the 16 bit linear raw and it really is an amazing format to work with. So much so that I will always use it whenever possible.

But now as well as 16 bit linear raw the R7 can record 16 bit linear XOCN. Now, I’ll be completely honest here, I’m really not sure what the difference is between raw and XOCN. As far as I can tell XOCN is very, very similar to raw but sufficiently different to raw to avoid infringing on patents held by other manufacturers for compressed raw. XOCN is more highly compressed than Sony’s raw, but in every test I’ve done I have found it hard to spot any compression problems or any significant difference between XOCN and the original 3:1 raw.

So, I hear you ask…. “If it’s really that good what don’t we just do away with XAVC and use XOCN?” Well that is a good question. It all depends on processing power. XAVC is a traditional codec so inside the codec is a normal video image, so the only thing a computer has to do to play it back is uncompress the codec. XOCN is a compressed wrapper that contains sensor data, in order to view the image the computer has to uncompress the data and then it has to construct the image from the data. So you need a really good graphics card in a decent computer to work with XOCN. But if you do have a decent edit or grading workstation you should find XOCN straight forward to work with, it doesn’t require specialist cards to accelerate the decoding as Red raw does.

The key benefit that XOCN brings over traditional video is that it is 16 bit. 10 bit video is pretty good. In a 10 bit video you have almost 1000 tonal values, not bad when you consider that we have been using 8 bit for decades with only 235 shades. But 16 bit brings the potential for a whopping great 65,535 shades. This starts to make a big difference when you are extensively manipulating the image in post production. Any of you that are in to photography will know that you can push and pull a 16 bit raw photograph far, far further than an 8 bit jpeg. 16 bit video is no different.

But what’s really amazing about XOCN is you get almost all the benefits of linear raw but in a file size smaller than the same resolution 10 bit ProResHQ. If you use XOCN-LT the files are roughly half the size of ProResHQ. This means your media lasts a sensible amount of time and backups, transfers and archiving are all much easier, much faster than with uncompressed raw. Sony’s 3:1 compressed raw from the R5 has always been pretty easy to deal with. XOCN is even easier. Using XOCN-LT you can squeeze well over 2 hours of 16bit 4K on to a 512GB AXS card! In fact the file sizes are only marginally larger than XAVC class 480.

xocn-data-rates-1024x276 What is XOCN? Why is it so good, why do we need it?

The reduction in data rates becomes really significant if you shoot at high frame rates. As 50p and 60p productions become more common XOCN allows production companies to shoot 60fps with the benefits of 16 bit data but with files sizes barely any bigger than 24fps ProResHQ. If you have a Sony PMW-F55 you can shoot at 120fps in 4K using XOCN and the files are twice as big as 24fps raw.

For further information on XOCN please take a look at this page from Sony, it’s very informative and has a very good example of why 16 bit data is important, especially if you are shooting for HDR.

https://pro.sony.com/bbsc/ssr/show-highend/resource.solutions.bbsccms-assets-show-highend-f55xocn.shtml

Video Tutorials for the FS5. Picture Profiles and Raw Recording.

I was recently asked by Sony to produce some videos to help users get the most from the PXW-FS5. The videos and articles can now be found on Sony’s website by following the links below. Part 1 covers the camera setup including using Picture Profiles to change the way the images look. Part 2 covers the special effects modes including S&Q, super-slow-motion, clear image zoom and the variable ND filter. Part 3 looks at the raw option for the FS5.

PXW-FS5 Shooting Tips Part 1. Camera Setup and Picture Settings.

PXW-FS5 Shooting Tips Part 2. Slow and Quick Motion, Variable ND, Clear Image Zoom.

PXW-FS5 Recording Raw and using the Raw output option (Atomos Shogun Flame and Convergent Design Odyssey 7Q used as examples).

Big Update for Sony Raw Viewer.

rawviewer-01-large-e1480363307344 Big Update for Sony Raw Viewer.
Sony’s Raw Viewer for raw and X-OCN file manipulation.

Sony’s raw viewer is an application that has just quietly rumbled away in the background. It’s never been a headline app, just one of those useful tools for viewing or transcoding Sony’s raw material. I’m quite sure that the majority of users of Sony’s raw material do their raw grading and processing in something other than raw viewer.

But this new version (2.3) really needs to be taken very seriously.

Better Quality Images.

For a start Sony have always had the best de-bayer algorithms for their raw content. If you de-bayer Sony raw in Resolve and compare it to the output from previous versions of Raw Viewer, the raw viewer content always looked just that little bit cleaner. The latest versions of Raw Viewer are even better as new and improved algorithms have been included! It might not render as fast, but it does look very nice and can certainly be worth using for any “problem” footage.

Class 480 XAVC and X-OCN.

Raw Viewer version 2.3 adds new export formats and support for Sony’s X-OCN files. You can now export to both XAVC class 480 and class 300, 10 or 12bit ProRes (HD only unfortunately), DPX and SStP.  XAVC Class 480 is a new higher quality version of XAVC-I that could be used as a ProResHQ replacement in many instances.

Improved Image Processing.

Color grading is now easier than ever thanks to support for Tangent Wave tracker ball control panels along with new grading tools such as Tone Curve control. There is support for EDL’s and batch processing with all kind of process queue options allowing you to prioritise your renders. Although Raw Viewer doesn’t have the power of a full grading package it is very useful for dealing with problem shots as the higher quality de-bayer provides a cleaner image with fewer artefacts. You can always take advantage of this by transcoding from raw to 16 bit DPX or Open EXR so that the high quality de-bayer takes place in Raw Viewer and then do the actual grading in your chosen grading software.

HDR and Rec.2100

If you are producing HDR content version 2.3 also adds support for the PQ and HLG gamma curves and Rec.2100 It also now includes HDR waveform displays. You can use Raw Viewer to create HDR LUT’s too.

So all-in-all Raw Viewer has become a very powerful tool for Sony’s raw and XOCN content that can bring a noticeable improvement in image quality compared to de-bayering in many of the more commonly used grading packages.

Download Link for Sony Raw Viewer: http://www.sonycreativesoftware.com/download/rawviewer

 

Creative Composition and Digital Cinematography Workshops – Singapore.

965437_547020298723068_486905373_o-300x168 Creative Composition and Digital Cinematography Workshops - Singapore.
Alister Chapman providing a workshop.

I’m running some workshops for Singapore Media Academy in September. Spaces are limited and I don’t get to visit Asia as much as I used to. So if you are interested in attending one of my highly regarded and popular workshops here is a great opportunity.

CREATIVE COMPOSITION:
The first is on Creative Composition. Good shot composition can make or break a production. In the workshop I will guide you through ways to achieve images that will draw the audience in, focus the viewers attention or create different emotional reactions.  I will show you how to deal with composition in moving shots, something that can be difficult. We will use case studies of well known movies to see clever use of classic techniques such as the rule of thirds, vanishing lines or Fibonacci curves. We will see how subtle lighting changes can be used to direct the audiences gaze. From the framing of a simple interview to the staging of a complex scene the workshop will help you develop engaging and interesting images. Understanding basic composition is one of the keys to great productions whether it’s for TV news or the cinema.
DIGITAL CINEMATOGRAPHY, LOG AND RAW (Plus HDR).
The second workshop is on Digital Cinematography, Log and Raw. This is an essential workshop for those serious about obtaining the best possible images with a modern electronic video camera. I will explain the differences between standard gammas, log and raw in a way that’s easy to understand but will give you all the information you need to be able to make informed decisions about which to use and when. Next I will teach you how to expose Log and Raw looking closely at how to use exposure offsets for the best results in differing lighting conditions. Then we will look at Look Up Tables. I’ll show you how and when to use them and how to easily create your own. We will finish with some practical end to end workflow sessions where you will develop your own LUT’s, shoot with log or raw and then perform a basic grade on your content. This will include how to use color managed grading tools such as the Academy of Motion Pictures workflow “ACES”. There’s no hard to understand mathematics, no complex formula’s, just easy to understand explanations and great practical tips and advice that will make log and raw easy to understand and use. I will also include how to expose and shoot for HDR and what you need to consider for HDR productions. More details can be found with the links below: