Category Archives: PMW-F55

Hedén VLC Zoom and Focus Control.

Hedén VLC Zoom and Focus Control.

Sorry for the lack of post recently, but I’ve been busy on various overseas shoots using the Sony Venice camera. I’ll be writing these up in due course.

My 2 favourite and most used lenses are my Fujinon MK zooms . I use the MK18-55 and MK50-135 on both my PMW-F5 and on my FS5. I’ve also used them on a Sony Venice. They are really great lenses. But one thing that I’ve always felt would make them a bit better is a power zoom.

Enter the Hedén VLC system.

AJC04868-1024x683 Hedén VLC Zoom and Focus Control.
Heden servo motor to turn a non servo zoom into a power zoom. In this case on a Fujinon MK18-55 lens.

For starters the Hedén VLC system allows you to turn a non motorised zoom lens into a power zoom lens, but the Heden VLC system is more than just a zoom motor and control box. It can be expanded with a second motor to not only motorize the zoom but also provide an electronic focus control (although as yet I have not tried this).

Never heard of Hedén before? Well if you work in higher end features and productions you will probably have come across them before as they are a highly regarded Swedish manufacturer of electronic follow focus and zoom systems used in high end Cinematography. For me though, until now their products have been beyond my reach. One of their standard follow focus motors costs around £1.6K/$2K. However the motors and components used in the VLC systems are much cheaper, yet still meet Hedén’s exacting standards.  A complete VLC zoom system, including motor, costs around $2,100 USD. It’s still not a “cheap” item, but the system is of very high quality and surprisingly flexible, so it is something that should last many years and work with not just todays cameras and lenses but also whatever comes next.

The VLC system comprises several components. A control box, a motor or motors along with various attachment brackets for the motors depending on your application and a set of cables.

AJC04872-1024x683 Hedén VLC Zoom and Focus Control.
Heden VLC control box.

The first time I played with the system it was an early development unit on my FS5. On the FS5 the system is controlled using the Lanc control functions built into the cameras existing handgrip. The cable from the hand grip that normally plugs directly into the camera body is plugged into a breakout cable from the VLC control box and then another connection from the control box plugs into the FS5. This way the handgrip controls the FS5 as normal, but now the zoom rocker on the handgrip also smoothly and accurately controls the Hedén zoom motor. All the hand grips other functions continue to operate as usual.

AJC04881-1024x683 Hedén VLC Zoom and Focus Control.
The Hedén VM35 servo motor for the VLC zoom and focus system.

The motor used by the VLC system is a very high quality compact servo motor and gearbox with digital position and speed feedback. So the controller knows exactly how fast the motor is turning and where it is in it’s operating cycle. The first time you use the system it needs to be calibrated for the lens you are using. This is done quickly and simply, just by pressing the small CAL button on the controller. Once pressed the motor quickly runs back and forwards to find the lenses end stops.

AJC04892-1024x683 Hedén VLC Zoom and Focus Control.
The CAL button used to calibrate the Hedén VLC zoom system.

A very nice feature is that when the motor isn’t being driven it can be turned quite easily. This means that unlike some other similar systems you don’t have to mechanically or physically disengage the motor from the lenses pitch gears to perform a manual zoom. In fact, the motor acts as a soft damping system and helps make manual zooms smoother.

My only gripe about the VLC system is the size of the control box. On a camera as small as the FS5 the control box is quite a big lump to add.

AJC04878-1024x683 Hedén VLC Zoom and Focus Control.
The Hedén VLC system mounted on an FS5 and Fujinon MK lens.
AJC04866-1024x683 Hedén VLC Zoom and Focus Control.
I have the Hedén VLC control box mounted on the rear of the FS5’s handle using the 3M Dual Lock provided with the kit.

For power I run it from a Dynacore BP-U type battery that has a D-Tap output. There is no on/off switch, so you turn it off by unplugging it, but the system doesn’t use much power and I barely noticed any difference in the life of the camera battery when using it this way.

The control box has controls for the motor speed, torque and direction. These controls allow you to fine tune the way the motor operates, so if you want you can have a fast snappy zoom, or if you prefer you can have a slower zoom. The control buttons are mounted below a soft waterproof membrane to protect the unit from dust and moisture. There is also a small LED display that shows the torque and speed settings. When zooming in or out this also shows the requested zoom speed. All the cables are connected to the box using very high quality Lemo connectors.

AJC04874-1024x683 Hedén VLC Zoom and Focus Control.
The Hedén VLC control box mounted on an FS5

I found that the FS5 zoom rocker with it’s limited travel seemed to work best for me when the motor was set to quite a slow speed. The motor has lots of torque, so it should have no problem driving lenses with quite stiff zoom rings. However I probably wouldn’t try to use it with a DSLR zoom. I dabbled with producing a zoom motor for DSLR zooms some years back, but found it very difficult. Most DSLR zooms are quite stiff, often have tight spots as well as only limited travel. This makes it very difficult to get a very smooth motion. Feel free to try it with whatever lenses it is that you have, but I think you will need to test the functionality with each photo zoom lens to see how it copes. For proper video and cinemas lenses with smooth zoom rings the VLC system should work very well.

With the Fujinon MK lenses the motor can be attached to the barrel of the lens via a dedicated bracket. There is also a bracket for two motors for those that want to motorize not only the zoom but also the focus.

vm35-60 Hedén VLC Zoom and Focus Control.
Dual motor bracket for the Fujinon MK lenses allows both a zoom and focus motor to be attached.

The benefit of having the motor on the lens is that it’s always in the right place and you don’t need rails etc. The downside is that if you have more than one lens you need to either, swap the motor and brackets each time you change lens, have multiple brackets or if you have really deep pockets a motor and bracket for every lens. Swapping the motor from bracket to bracket is very quick and easy, just loosen the thumbscrew and the motor slides out. So I would recommend having a bracket on each lens and simply swapping the motor over. The other alternative is to use one of the Hedén rail brackets to attach the motor to 15mm rails, then when you swap lenses the motor stays attached to the rails and it’s just a case of lining the motor up with the pitch gear on the lens.

vm35-40-1024x684 Hedén VLC Zoom and Focus Control.
Rod mount for attaching a single Hedén VLC system motor to a 15mm rod.

 

Not long after starting to use the system on my FS5 I was informed that there was an update for the system that could work with any 3rd party Lanc Controller. So I decided to give this a try on my PMW-F5. To make this work you need an additional aftermarket Lanc zoom controller. These are readily available and there are lots of choices.

AJC04889-1024x683 Hedén VLC Zoom and Focus Control.
The Hedén VLC zoom system mounted on my PMW-F5 and Fujinon MK lens. It’s much easier to find a place for the control box on larger cameras like the F5/F55 and FS7.

The Manfrotto controller I used allowed me to operate the zoom from from the pan bar of my tripod. Great for studio or ENG type applications. The only thing you don’t get with an F5 and a Lanc controller is control over record start and stop as the F5 itself doesn’t support Lanc control. So you still have to press the record button on the camera. But this isn’t a big deal and having the ability to zoom from the pan bar is great for so many applications.

AJC04888-1024x683 Hedén VLC Zoom and Focus Control.
Manfrotto Lanc controller mounted to the tripod pan bar.

Overall I am very impressed with the system. The degree of control you have over the lens is quite remarkable, it’s just as good as the control you get with a high end ENG zoom.  It’s very easy to setup and allows you to perform silky smooth zooms with ease. If you want smooth, slow starts to the zoom or extremely slow zooms, both are easily achieved with the Hedén VLC system.

I probably wouldn’t use it for every shoot, especially with the FS5 as the control box is a little bulky. With the F5 or FS7 and other larger cameras this is much less of a concern, so I will probably use it more often with these cameras. I also want to explore using it with Lanc controller that I can use with handgrips when handheld (perhaps using the Vocas Arri rosette kit for remote attachment of the FS5 hand grip).

The biggest strength of this system for me though, is that it isn’t actually lens or camera specific. You can use it with just about any lens and camera. So as you add more lenses to your collection, or if you change camera, you will still be able to use the VLC system just by making sure you have the right motor bracket. The 15mm rod bracket should work with just about any lens. This means that it’s a system that should last you a very long time.

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What’s wrong with my viewfinder, my old camera had a much better viewfinder!

This is something that keeps popping up all over the place and it’s not just one camera that attracts this comment. Many do, from the FS5 to the FS7 to the F55, plus cameras from other manufacturers too.
One common factor is that very often this relates to the newer super35mm cameras. Cameras designed to give a more rounded, film like look, often cameras with 4K or higher resolution sensors.
I think many people perceive there is an issue with their viewfinder because they come to these new high resolution, more rounded and film like cameras  from traditional television centric camcorders that use detail correction, coring and aperture correction to boost the image sharpness.
SD and even HD television broadcasting relies heavily on image sharpening so that viewers perceive a crisp, sharp image at any viewing distance and with any screen size (although on really big screens this can really ruin the image).
This works by enhancing and boosting the contrast around edges. This is standard practice on all normal HD and SD broadcast cameras. Especially camera that use a 3 chip design with a prism as the prism will often reduce the images edge contrast.
As most people will prefer a very slightly sharpened HD image or a heavily sharpened SD image over an unsharpened one, it’s sharpened by default. This means that the images those cameras produce will tend to look sharp even on screens that have a lower resolution than that of the camera because the edges remain high contrast even when the viewing resolution is reduced and as a result look sharp.
Most current manufacturer supplied LCD EVF’s run at 1/4″ HD with 940 x 560 pixels (each pixel made up of an RGB 3 dot matrix). In addition many of the 3rd party VF’s such as the very popular Alphatron are the same because they all use the same mass produced, relatively low cost panels – panels that are also used for mobile phones and many other devices. 
 
The problem then is that when you move to a camera that doesn’t add any image sharpening, if you view the cameras image on a lower resolution screen the image looks soft because — it is. There is no detail correction to compensate. Incidentally this is why often these same cameras can look a bit soft in HD and very soft in SD compared to other traditional or detail corrected cameras. But, that slightly softer, less processed look helps contribute to their more film like look. This softness and lack of sharpening/processing is particularly noticeable if you use the focus mag function as you are then looking at an enlarged but completely un-sharpened image.
 
It could be argued that the viewfinder should sharpen the image to compensate. Some of the more expensive viewfinders can do this using their own sharpening processes. But the image that you are then seeing is not the picture that is being recorded and this isn’t always ideal. If it is over done then it can make the entire image look sharp even when it isn’t fully in focus. Really you want to be looking at exactly the image that the camera is recording so that you can spot any potential problems. But that then makes focussing tricky.
 
There are a few 3rd party viewfinders such as the Gratical that have higher resolutions. The Gratical and Eye have screens that are 1280×1024, but in normal use you only use 1280×720 for the image area. This certainly helps, but even the 1:1 pixel zoom on these can look soft and blurry as you loose the viewfinders peaking function when you crop in.
 
Sony’s Venice and the F55/F5 can use Sony’s new DVF-EL200 OLED viewfinder. This costs around £4.5K ($6K) and has a 1920×1080 screen. It’s a beautiful image, but even this needs a fairly good dose of peaking to artificially sharpen the image to be able to see that last critical bit of focus. Again when you zoom in the image looks soft and a bit blurry (even on a Venice) as the camera itself is not adding any sharpening. The peaking function on the DVF-EL200 is quite sophisticated as it only enhances the highest frequency parts of the image, so only sharp edges and fine details are boosted.
 
Go back to the days of black and white tube viewfinders and these used tons of peaking to make them useable. Traditional SD and HD cameras add sharpening to their pictures, but most of our modern large sensor 4K camera do not and as a result often the viewfinder images appear soft compared to what we used to see on older cameras or still see today on cameras that do sharpen the pictures.
 
All of this makes it hard to nail your focus, especially if shooting 4K. Even with a DVF-EL200 on a Venice I struggle at times and rely heavily on image mag (which is still difficult) or better still a much larger monitor with a good sun shade and if necessary some reading glasses to allow you to focus on it up close.

So before you get too critical of your viewfinders performance do also consider all of the above. Try to see how another similar viewfinder looks on your camera (for example an Alphatron on an FS7). Perhaps try a higher resolution viewfinder such as a Gratical, but don’t expect miracles from a small, relatively low resolution screen on a modern digital cinema camera. This really is one of those areas where you can’t beat a big, high resolution screen.

Venice Look LUT’s For 14 stop cameras A7, FS5, FS7, F5, F55 etc.

Hello all. So after numerous problems for some people trying to download the official Sony s709 LUT for Venice, I decided to create my own Venice Look LUT’s. These LUT’s have been created using image matching techniques plus some small tweaks and adjustments to make the LUT’s work well with the 14 stop cameras.

Venice is a 15 stop camera with a new sensor and as a result the official s709 LUT’s are not quite right for the current 14 stop cameras like the FS5, PMW-F55, FS7 and even the A7 series. So the LUT that I have created is slightly different to allow for this.

The end result is a LUT that gets you really close to the way Venice looks. It won’t magically turn your FS5 into a Venice, there is something very, very nice about the way Venice handles the extremes of it’s dynamic range, plus Venice has Sony’s best colour filters (similar to the F55 and F65). So Venice will always be that one very nice step up. But these LUT’s should get you close to the default Venice 709 look. This LUT should NOT be used with Venice as it this LUT is restricted to 14 stops.

Of course do remember that the default look and indeed the official s709 LUT was designed as a first pass look. An instant viewing output for a DIT or for on set viewing. It is not really meant to be the final finished look. It would be normal to grade the Venice material, perhaps from scratch rather than using the s709 LUT for the final output. But, s709 is what comes out of the cameras SDI connectors if you use the default LUT/Look. This is what this LUT set mimics, with some tweaks for the lower cost cameras.

This is one of the largest and most comprehensive LUT sets I have ever created. There are versions designed specifically for grading in Resolve or other grading suites. The bulk of the LUT’s are designed to be used with S-Log3 and SGamut3.cine. There are monitoring versions with offsets for use in monitors such as the Atomos range. I have created a set with offsets for both the Zacuto and Small HD viewfinders and monitors and finally I have also created sets of LUT’s for use with S-Log2 so users of the original A7s or those that wish to shoot with S-Log2 on an 8 bit camera are not left out.

The LUT’s work best with the PMW-F55 as this has the closest native color to the Venice camera, but I think they work really well on the rest of the Sony range.

If you find the LUT’S useful, please consider buying me a beer or a coffee using the “Buy Now” button below. There are different drink options depending on what you feel is fair, it takes time to prepare these and there are costs associated with hosting the files. I’m not paid to run this website and every little bit helps and is greatly appreciated.

If you don’t wish to buy me a coffee, that’s cool. But please don’t host the files elsewhere. Feel free to link back here and share the link, but please don’t distribute these anywhere else.

Here’s the link to the zip file containing the my Venice Look LUT set:

Click Here to download Alister’s Venice Look LUTs V2


Type



pixel Venice Look LUT's For 14 stop cameras A7, FS5, FS7, F5, F55 etc.

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Sony Venice LUT.

Sony’s new Rec-709 style LUT for the Venice camera is now available. This Lut was designed to work with the Venice camera to provide a new film like look with beautiful highlight roll-off.  In it’s current form it only works with S-Log3/S-Gamut3.cine material, although you could use the excellent LUTCalc app to create different versions.

Although designed for Venice the LUT works really well with footage from the FS5, FS7, F5 and F55 etc.

You can download the base LUT from here until the end of July. https://dmpce.cimediacloud.com/mediaboxes/8374a677e6224da2a170bd841f64302d

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.

Revised and improved HLG camera LUT for FS7, F5 and F55.

I have created a new and improved HLG camera LUT for the PXW-FS7, PMW-F5 and PMW-F55 cameras. This 3D LUT can be used to shoot HLG directly by baking the LUT in to the recordings in camera. This allows you to create “instant HDR” footage that just like the HLG footage from an FS5 or Z90 does not need to be graded or modified to provide an HDR image on an equipped HDR TV. Skin tones should be exposed at around 55-60% and white at around 70-75%.

Click here to download the LUT AC-HLGSL3-V2.cube

Beware the LC709 LUT double exposure offset.

The use o f the LC709 Type A LUT in Sony’s Cinealta cameras such as the PXW-FS7 or PMW-F55 is very common. This LUT is popular because it was designed to mimic the Arri cameras when in their Rec-709 mode. But before rushing out to use this LUT and any of the other LC709 series of LUT’s there are some things to consider.

The Arri cameras are rarely used in Rec-709 mode for anything other than quick turn around TV. You certainly wouldn’t normally record this for any feature or drama productions. It isn’t the “Arri Look” The Arri look normally comes as a result of shooting using Arri’s LogC and then grading that to get the look you want. The reason it exists is to provide a viewable image on set. It has more contrast than LogC and uses Rec 709 color primaries so the colors look right, but it isn’t Rec-709. It squeezes almost all of the cameras capture range into a something that can be viewed on a 709 monitor so it looks quite flat.

Because a very large dynamic range is being squeezed into a range suitable to be viewed on a regular, standard dynamic range monitor the white level is much reduced compared to regular Rec-709. In fact, white (such as a white piece of paper) should be exposed at around 70%. Skin tones should be exposed at around 55-60%.

If you are shooting S-Log on a Sony camera and using this LUT to monitor, if you were to expose using conventional levels, white at 85-90% skin tones at 65-70%, then you will be offsetting your exposure by around +1.5 stops. On it’s own this isn’t typically going to be a problem. In fact I often come across people that tell me that they always shoot at the cameras native EI using this LUT and get great, low noise pictures. When I dig a little deeper I often find that they are exposing white at 85% via the LC709 LUT. So in reality they are actually shooting with an exposure the equivalent of +1 to +1.5 stops over the base level.

Where you can really run into problems is when you have already added an exposure offset. Perhaps you are shooting on an FS7 where the native ISO is 2000 ISO and using an EI of 800. This is a little over a +1 stop exposure offset. Then if you use one of the LC709 LUT’s and expose the LUT so white is at 90% and skin tones at 70% you are adding another +1.5 stops to the exposure, so your total exposure offset is approaching 3 stops. This large an offset is rarely necessary and can be tricky to deal with in post. It’s also going to impact your highlight range.

So just be aware that different LUT’s require different white and grey levels and make sure you are exposing the LUT at it’s correct level so that you are not adding an additional offset to your desired exposure.

DaVinci Resolve, ACES and the “Sony Raw” input transform.

A quick heads up for users of Resolve with Sony Raw and X-OCN. Don’t make the same mistake I have been making. For some time I have been unhappy with the way the Sony raw looked in DaVinci Resolve and ACES prior to grading. Apparently there used to be a small problem with the raw input transform that could lead to a red/pink hue getting added to the footage. This problem was fixed some time ago. You should now not use the the “Sony Raw” input transform, if you do, it will tint your Raw or X-OCN files slightly pink/red. Instead you should select “no transform”. With no transform selected my images look so much nicer and match Sony’s own Raw Viewer so much better. Thanks to Nick Shaw of Antler Post for helping me out on this and all on the CML list.

How can 16 bit X-OCN deliver smaller files than 10 bit XAVC-I?

Sony’s X-OCN (XOriginal Camera Negative) is a new type of codec from Sony. Currently it is only available via the R7 recorder which can be attached to a Sony PMW-F5, F55 or the new Venice cinema camera.

It is a truly remarkable codec that brings the kind of flexibility normally only available with 16 bit linear raw files but with a files size that is smaller than many conventional high end video formats.

Currently there are two variations of X-OCN.

X-OCN ST is the standard version and then X-OCN LT is the “light” version. Both are 16 bit and both contain 16 bit data based directly on what comes off the cameras sensor. The LT version is barely distinguishable for a 16 bit linear raw recording and the ST version “visually lossless”. Having that sensor data in post production allows you to manipulate the footage over a far greater range than is possible with tradition video files. Traditional video files will already have some form of gamma curve as well as a colour space and white balance baked in. This limits the scope of how far the material can be adjusted and reduces the amount of picture information you have (relative to what comes directly off the sensor) .

Furthermore most traditional video files are 10 bit with a maximum of 1024 code values or levels within the recording. There are some 12 bit codecs but these are still quite rare in video cameras. X-OCN is 16 bit which means that you can have up to 65,536 code values or levels within the recording. That’s a colossal increase in tonal values over traditional recording codecs.

But the thing is that X-OCN LT files are a similar size to Sony’s own XAVC-I (class 480) codec, which is already highly efficient. X-OCN LT is around half the size of the popular 10 bit Apple ProRes HQ codec but offers comparable quality. Even the high quality ST version of X-OCN is smaller than ProRes HQ. So you can have image quality and data levels comparable to Sony’s 16 bit linear raw but in a lightweight, easy to handle 16 bit file that’s smaller than the most commonly used 10 bit version of ProRes.

But how is this even possible? Surely such an amazing 16 bit file should be bigger!

The key to all of this is that the data contained within an X-OCN file is based on the sensors output rather than traditional video.  The cameras that produce the X-OCN material all use bayer sensors. In a traditional video workflow the data from a bayer sensor is first converted from the luminance values that the sensor produces into a YCbCr or RGB signal.

So if the camera has a 4096×2160 bayer sensor in a traditional workflow this pixel level data gets converted to 4096×2160 of Green plus 4096×2160 of Red, plus 4096×2160 of Green (or the same of Y, Cb and Cr). In total you end up with 26 million data points which then need to be compressed using a video codec.

Bayer-to-RGB How can 16 bit X-OCN deliver smaller files than 10 bit XAVC-I?However if we bypass the conversion to a video signal and just store the data that comes directly from the sensor we only need to record a single set of 4096×2160 data points – 8.8 million. This means we only need to store 1/3rd as much data as in a traditional video workflow and it is this huge data saving that is the main reason why it is possible for X-OCN to be smaller than traditional video files while retaining amazing image quality. It’s simply a far more efficient way of recording the data from a bayer camera.

Of course this does mean that the edit or playback computer has to do some extra work because as well as decoding the X-OCN file it has to be converted to a video file, but Sony developed X-OCN to be easy to work with – which it is. Even a modest modern workstation will have no problem working with X-OCN. But the fact that you have that sensor data in the grading suite means you have an amazing degree of flexibility. You can even adjust the way the file is decoded to tailor whether you want more highlight or shadow information in the video file that will created after the X-OCN is decoded.

Why isn’t 16 bit much bigger than 10 bit? Normally a 16 bit file will be bigger than a 10 bit file. But with a video image there are often areas of information that are very similar. Video compression algorithms take advantage of this and instead of recording a value for every pixel will record a single value that represents all of the similar pixels. When you go from 10 bit to 16 bit, while yes, you do have more bits of data to record a greater percentage of the code values will be the same or similar and as a result the codec becomes more efficient. So the files size does increase a bit, but not as much as you might expect.

So, X-OCN, out of the gate, only needs to store 1/3rd of the data points of a similar traditional RGB or YCbCr codec. Increasing the bit depth from the typical 10 bit bit depth of a regular codec to the 16 bits of X-OCN does then increase the amount of data needed to record it. But the use of a clever algorithm to minimise the data needed for those 16 bits means that the end result is a 16 bit file only a bit bigger than XAVC-I but still smaller than ProRes HQ even at it’s highest quality level.

Sony Venice. Dual ISO’s, 1 stop ND’s and Grading via Metadata.

With the first of the production Venice cameras now starting to find their way to some very lucky owners it’s time to take a look at some features that are not always well understood, or that perhaps no one has told you about yet.

Dual Native ISO’s: What does this mean?

An electronic camera uses a piece of silicon to convert photons of light into electrons of electricity. The efficiency at doing this is determined by the material used. Then the amount of light that can be captured and thus the sensitivity is determined by the size of the pixels. So, unless you physically change the sensor for one with different sized pixels (which will in the future be possible with Venice) you can’t change the true sensitivity of the camera. All you can do is adjust the electronic parameters.

With most video cameras the ISO is changed by increasing the amount of amplification applied to the signal coming off the sensor. Adding more gain or increasing the amplification will result in a brighter picture. But if you add more amplification/gain then the noise from the sensor is also amplified by the same amount. Make the picture twice as bright and normally the noise doubles.

In addition there is normally an optimum amount of gain where the full range of the signal coming from the sensor will be matched perfectly with the full recording range of the chosen gamma curve. This optimum gain level is what we normally call the “Native ISO”. If you add too much gain the brightest signal from the sensor would be amplified too much and exceed the recording range of the gamma curve. Apply too little gain and your recordings will never reach the optimum level and darker parts of the image may be too dark to be seen.

As a result the Native ISO is where you have the best match of sensor output to gain. Not too much, not too little and hopefully low noise. This is typically also referred to as 0dB gain in an electronic camera and normally there is only 1 gain level where this perfect harmony between sensor, gain and recording range is achieved, this becoming the native ISO.

Side Note: On an electronic camera ISO is an exposure rating, not a sensitivity measurement. Enter the cameras ISO rating into a light meter and you will get the correct exposure. But it doesn’t really tell you how sensitive the camera is as ISO has no allowance for increasing noise levels which will limit the darkest thing a camera can see.

Tweaking the sensor.

However, there are some things we can tweak on the sensor that effect how big the signal coming from the sensor is. The sensors pixels are analog devices. A photon of electricity hits the silicone photo receptor (pixel) and it gets converted into an electron of electricity which is then stored within the structure of the pixel as an analog signal until the pixel is read out by a circuit that converts the analog signal to a digital one, at the same time adding a degree of noise reduction. It’s possible to shift the range that the A to D converter operates over and the amount of noise reduction applied to obtain a different readout range from the sensor. By doing this (and/or other similar techniques, Venice may use some other method) it’s possible to produce a single sensor with more than one native ISO.

A camera with dual ISO’s will have two different operating ranges. One tuned for higher light levels and one tuned for lower light levels. Venice will have two exposure ratings: 500 ISO for brighter scenes and 2500 ISO for shooting when you have less light. With a conventional camera, to go from 500 ISO to 2500 ISO you would need to add just over 12dB of gain and this would increase the noise by a factor of more than 4. However with Venice and it’s dual ISO’s, as we are not adding gain but instead altering the way the sensor is operating the noise difference between 500 ISO and 2500 ISO will be very small.

You will have the same dynamic range at both ISO’s. But you can choose whether to shoot at 500 ISO for super clean images at a sensitivity not that dissimilar to traditional film stocks. This low ISO makes it easy to run lenses at wide apertures for the greatest control over the depth of field. Or you can choose to shoot at the equivalent of 2500 ISO without incurring a big noise penalty.

One of Venice’s key features is that it’s designed to work with Anamorphic lenses. Often Anamorphic lenses are typically not as fast as their spherical counterparts. Furthermore some Anamorphic lenses (particularly vintage lenses) need to be stopped down a little to prevent excessive softness at the edges. So having a second higher ISO rating will make it easier to work with slower lenses or in lower light ranges.

COMBINING DUAL ISO WITH 1 STOP ND’s.

Next it’s worth thinking about how you might want to use the cameras ND filters. Film cameras don’t have built in ND filters. An Arri Alexa does not have built in ND’s. So most cinematographers will work on the basis of a cinema camera having a single recording sensitivity.

The ND filters in Venice provide uniform, full spectrum light attenuation. Sony are incredibly fussy over the materials they use for their ND filters and you can be sure that the filters in Venice do not degrade the image. I was present for the pre-shoot tests for the European demo film and a lot of time was spent testing them. We couldn’t find any issues. If you introduce 1 stop of ND, the camera becomes 1 stop less sensitive to light.  In practice this is no different to having a camera with a sensor 1 stop less sensitive. So the built in ND filters, can if you choose, be used to modify the base sensitivity of the camera in 1 stop increments, up to 8 stops lower.

So with the dual ISO’s and the ND’s combined you have a camera that you can setup to operate at the equivalent of 2 ISO all the way up to 2500 ISO in 1 stop steps (by using 2500 ISO and 500 together you can have approximately half stops steps between 10 ISO and 650 ISO). That’s an impressive range and at no stage are you adding extra gain. There is no other camera on the market that can do this.

On top of all this we do of course still have the ability to alter the Exposure Index of the cameras LUT’s to offset the exposure to move the exposure mid point up and down within the dynamic range. Talking of LUT’s I hope to have some very interesting news about the LUT’s for Venice. I’ve seen a glimpse of the future and I have to say it looks really good!

METADATA GRADING.

The raw and X-OCN material from a Venice camera (and from a PMW-F55 or F5 with the R7 recorder) contains a lot of dynamic metadata. This metadata tells the decoder in your grading software exactly how to handle the linear sensor data stored in the files. It tells your software where in the recorded data range the shadows start and finish, where the mid range sits and where the highlights start and finish. It also informs the software how to decode the colors you have recorded.

I recently spent some time with Sony Europe’s color grading guru Pablo Garcia at the Digital Motion Picture Center in Pinewood. He showed me how you can manipulate this metadata to alter the way the X-OCN is decoded to change the look of the images you bring into the grading suite. Using a beta version of Black Magic’s DaVinci Resolve software, Pablo was able to go into the clips metadata in real time and simply by scrubbing over the metadata settings adjust the shadows, mids and highlights BEFORE the X-OCN was decoded. It was really incredible to see the amount of data that Venice captures in the highlights and shadows. By adjusting the metadata you are tailoring the the way the file is being decoded to suit your own needs and getting the very best video information for the grade. Need more highlight data – you got it. Want to boost the shadows, you can, at the file data level before it’s converted to a traditional video signal.

It’s impressive stuff as you are manipulating the way the 16 bit linear sensor data is decoded rather than a traditional workflow which is to decode the footage to a generic intermediate file and then adjust that. This is just one of the many features that X-OCN from the Sony Venice offers. It’s even more incredible when you consider that a 16 bit linear  X-OCN LT file is similar in size to 10 bit XAVC-I(class 480) and around half the size of Apples 10 bit ProRes HQ.  X-OCN LT looks fantastic and in my opinion grades better than XAVC S-Log. Of course for a high end production you will probably use the regular X-OCN ST codec rather than the LT version, but ST is still smaller than ProRes HQ. What’s more X-OCN is not particularly processor intensive, it’s certainly much easier to work with X-OCN than cDNG. It’s a truly remarkable technology from Sony.

Next week I will be shooting some more test with a Venice camera as we explore the limits of what it can do. I’ll try and get some files for you to play with.