Category Archives: cinematography

Auto Knee when shooting with Rec-709.

Like many cameras the Sony PXW-FS7, PMW-F5 and F55 use an automatic knee circuit to help the camera handle strong highlights or overexposure when shooting using standard gamma curves such as Rec-709 (STD gamma 5). On some ENG cameras there is a very similar function  called DCC (Dynamic Contrast Compensation) which is often selected via the Camera/Bars switch.

On the FS7, F5/F55 and many others the Auto Knee is on by default out of the factory. It can be turned on and off in the cameras paint settings. In most normal shooting situations, if you are correctly exposed the auto knee does a good job of bringing bright highlights down out of clipping.  The auto knee threshold is at around 90% brightness. Expose with objects brighter than 90% in your scene and the auto knee starts to kick in.

The correct exposure for white, such as a 90% reflectivity white card or white piece of paper in Rec-709 is 90%. Skin tones, plants, walls, roads and in fact most objects will normally be below white or below 90%. However direct light sources, such as the sky or direct reflections such as shiny car body work will be brighter than white. So the knee should only ever effect objects brighter than white if you are exposed correctly.  So for most situations it should not effect skin tones and the majority of the scene, just the bright highlights.

The auto knee detects highlight levels above 90% and tries to keep the highlight range below clipping by adding contrast compression to the highlights. The amount of compression depends on how strong the highlights are. As a result the auto knee effect will vary with exposure. If you have a scene with only a few highlights there will be some knee compression and it’s effect will only be seen above approx 90%. If you then open the aperture or have a lot of highlights the auto knee will increase the highlight compression to compensate. If the highlight range becomes very large then the knee will not only increase the amount of compression but also lower the knee point so more and more of the upper exposure range is effected by the knee. In extreme cases the knee point may get as low as 70-80% and this then starts to effect skin tones.

To prevent rapid fluctuations of the contrast in the highlight range the auto knee has a slight delay. This can result in a vicious circle where you open the iris a bit to help brighten the shot. The shot gets brighter. Then a couple of seconds later you look at the shot again and because the knee has now adjusted the highlights after it’s delay period it looks different to how it looked at the moment you made the initial adjustment. So you adjust again…. then the knee adjusts again and so on. Sometimes this lag can make it tricky to get your highlights to look exactly how you want.

Another common auto knee effect is to see the brighter parts of an entire image change as a result of a change in only a small part of the scene. A typical example would be an interview with a window in the background. As the highlight level in the bright window changes, perhaps as the sun comes and goes from behind passing clouds, the knee tries to compensate and all of the highlights in the scene go up and down in brightness whether they are over exposed or not. This looks very strange and can ruin an otherwise good looking shot.

If you are shooting in a studio against a white background the auto knee makes it impossible to get a brilliantly bright uniformly clipped white background. You increase your exposure to make the white background extra bright and because that white is now above 90% the auto knee treats it as a highlight and tries to control it’s brightness. The more you open the aperture the more the knee pulls down the white background, it never reaches clipping. Eventually you get to the point where the knee starts to effect the skin tones but your white backdrop still isn’t clipped. The image doesn’t look great.

In these cases the best thing to do is to turn off the Auto Knee. If you go into the paint settings you will find the knee settings. In most cases leave the knee on (except perhaps for the white studio example), but turn OFF the auto knee function. The fixed level knee will still give you a good highlight range but eliminate the pumping or other variable knee effects. Note that the knee options have no effect if using a Hypergamma or log. They only come into paly with standard gamma.

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. 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 far 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. 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% (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.

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

 

Fujinon MK18-55mm t2.9 E-Mount zoom lens.

Fujinon have a long history of producing excellent lenses. When I used to shoot motorsports, windsurfing and TV news I used to use Fujinon lenses on my 2/3″ Betacam, Digibeta and DVCAM camcorders. I still have a Fujinon remote zoom demand sitting in the cupboard. Today Fujinon still produce high quality lenses for broadcast cameras.

fujinon-tv-zoom-1024x683 Fujinon MK18-55mm t2.9 E-Mount zoom lens.

But Fujinon don’t just make lenses for broadcast cameras, they also make PL mount lenses for use with super 35mm cameras. Perhaps their best known cinema lenses are their “Cabrio” zoom lenses. When it was introduced the 19-90mm T2.9mm Cabrio was ground breaking as it offered a silky smooth zoom servo with an ENG style handgrip on a compact zoom lens.

fujinon_19_90mm_t2_9_cabrio_pl_895225-1024x1024 Fujinon MK18-55mm t2.9 E-Mount zoom lens.
The Fujinon Cabrio 19-90mm cinema zoom. A lens I’ve always enjoyed using and would love to own.

The 19-90 Cabrio was the workhorse servo zoom that many F5/F55, Red and Arri users had been wanting for a long time. I’ve used the Cabrio’s and they are great lenses, I’d love to own one, but my budget just won’t stretch that far. The 19-90 costs around $40K but it is a beautiful lens.

Aware of the demand for a similar lens at a lower cost, last year Fujinon introduced a more affordable 20-120mm T3.5 lens. However even though much cheaper, at £13.5K/$16K it is still quite an expensive lens, especially when you consider that a camera like the Sony FS7 only costs £6k/$8K.

FujifilmXK20-120-Leftftd-1400x739-1024x541 Fujinon MK18-55mm t2.9 E-Mount zoom lens.
The Fujinon XK20-120 cinema zoom. A servo unit can be added to turn it into a servo zoom.

That brings us to today. Fujinon have developed a pair of new lenses specifically for E-Mount cameras. An 18-55 and a 55-135. The 55-135 isn’t ready just yet but the wider one, the MK18-55 is, and I’ve been lucky enough to have been loaned one to test.

AJC03759-1024x683 Fujinon MK18-55mm t2.9 E-Mount zoom lens.
The new Fujinon MK18-55 E-Mount zoom lens.

As you can see the lens looks very similar to the more expensive XK20-120, but it’s actually a bit smaller and a lot lighter. The lens is an 18-55mm T2.9 (f2.8) Parfocal zoom. Parfocal means that the focus does not shift as you zoom as happens with most DSLR lenses. It’s E-Mount only, so you can’t use it on a Canon camera, but you can put it straight on to a FS5, FS7, even an A7S/A7R (The lens is designed for s35/APS-C so you need to use crop sensor mode or clear image zoom on a full frame sensor). No adapters needed! It’s a manual lens, no autofocus and there isn’t a zoom servo. But what you do get is beautiful image quality!

AJC03771-1024x683 Fujinon MK18-55mm t2.9 E-Mount zoom lens.
The MK18-55 T2.9 on my FS7

The short back focus distance of E-Mount compared to PL or EF makes it easier to produce an affordable high quality zoom lens, that’s why this lens is E-Mount only. To ensure that the lens remains parfocal on different cameras it has a backfocus adjustment ring. This ring also functions as a macro focus ring by pressing a small button. This allows you to focus on objects around 1ft/38cm from the lens. When not using macro the minimum focus distance is 0.85m/2ft9″.

macro1-1024x576 Fujinon MK18-55mm t2.9 E-Mount zoom lens.
The MK18-55’s macro function allows you to get very close to the subject. Click on the image for the full resolution frame grab.
dog-cu-1024x576 Fujinon MK18-55mm t2.9 E-Mount zoom lens.
Frame grab from the MK18-55mm Fujinon lens. Click on the image for the full resolution frame grab.

The iris is a 9 blade iris with curved blades that produces a pleasing bokeh both inside and outside of focus.

hedge1-1024x576 Fujinon MK18-55mm t2.9 E-Mount zoom lens.
Near and Far bokeh is pleasing thanks to a 9 blade iris. Click on the image for the full resolution frame grab.

To keep the weight down a lot of the lens exterior is made from plastic. It is quite a long (in length) lens. If it was all metal it would make a light camera like the FS7 front heavy, so while perhaps it doesn’t have the tactile feel of a $40K Cabrio it also doesn’t have the weight, the 19-90 is almost 6lb/2.7kg, the MK18-80 is just 34.6ox/980g. However it does feel well made. The focus, zoom and iris rings all feel very smooth and have just the right amount of rotation resistance and damping.

The focus ring has around 180 degrees of travel and the focus markings (in both metric and imperial) are clear and easy to read. Each ring also has a 0.8mm pitch gear ring.

AJC03769-1024x683 Fujinon MK18-55mm t2.9 E-Mount zoom lens.
The MK18-55 with the supplied lens hood.

In use I found the lens a pleasure to use. I can perform nice smooth manual zooms with ease. It is easy to focus with just the right amount of focus travel, not too much not too little.  Focus breathing is very well controlled and quite minimal. It’s certainly one of the best lenses I’ve used at this price point. It feels and behaves like a proper cinema lens.

So what about the image quality? This lens does not disappoint. The images are sharp from edge to edge, corner to corner throughout the zoom range, even when wide open at T2.9. Contrast is good and even when shooting into the sun, flare is minimal. A square lens hood is provided with the lens that works well, but of course you can also use it with a matte box if you wish.

To me the images from this lens look closer to the ones I get from prime lenses than a zoom. I can see this lens being used instead of a set of primes for many productions and it certainly works out very cost effective compared to a set of decent prime lenses.

709-cu1-1024x576 Fujinon MK18-55mm t2.9 E-Mount zoom lens.
The Fujinon MK18-55 at 55mm. Click on the image for the full resolution frame grab.
709-wide-1024x576 Fujinon MK18-55mm t2.9 E-Mount zoom lens.
The Fujinon MK18-55 at 18mm. Click on the image for the full resolution frame grab.

Chromatic aberration is well controlled and minimal and I didn’t notice any significant colour cast or tint. The lens is also remarkably free from geometric distortions (unlike the  Sony 18-105 that is supplied as a kit lens with the FS5 that’s full of all kinds of distortions). There is a little, but it’s no worse than most other wide zoom lenses and nothing that I am concerned about.

into-sun-1024x576 Fujinon MK18-55mm t2.9 E-Mount zoom lens.
Even shooting into the sun flare is minimal and shadows remain dark. Click on the image for the full resolution frame grab.

While T2.9 isn’t super fast it is at least a stop faster than most (all?) of the other budget cinema zooms on the market. Plus it’s absolutely useable at T2.9 unlike some other lenses that go a little soft or become prone to flare when wide open. I’d be perfectly happy to shoot at T2.9 all day.

dog-by-fire-1024x576 Fujinon MK18-55mm t2.9 E-Mount zoom lens.
Wide open at t2.9 the MK18-55 still produces a nice sharp image. Click on the image for the full resolution frame grab.

So, in case you haven’t noticed yet I really like this lens. It may not have the zoom range of the new Sony 18-110, but it’s a stop faster. It may not have the ability to be used on different mounts like the Canon 18-80 t4.4 but again it’s faster and has a real manual focus ring with hard stops and repeatable calibration. The new Zeiss 21-100 t2.9/t3.9 is interesting, but more expensive and not as wide nor as fast. You should be able to buy both the 18-55 and the 50-135 for less than the Zeiss.

So, if you are in the market for a proper digital cinema lens for your FS5 or FS7 do take a close look at the Fujinon MK18-55. I hope to get a chance to shoot some more interesting footage with this lens very soon and share it with you.

UPDATE: I should have anticipated this, I’ve been asked this many times today already. Given that the new Sony 18-110 f4 and the MK18-55mm are similar prices, which one would I choose?

I would probably choose the Fujinon, but my needs are not necessarily the same as others. Very often if I need a zoom lens I need a very big zoom range. For my storm chasing I use a Tamron 16-300mm dslr lens, I need a BIG zoom range. It’s a compromise, I know I can get better image quality with primes or a shorter zoom, but I often need to go from super wide to super long and the Tamron 19x 16-300mm zoom fits the bill.  For run and gun handheld work I actually quite like the cheaper Sony 18-105mm. Sure the focus is a bit wonky and it has a lot of different geometric distortions, but it’s really small, very light and the autofocus works OK. It does the job I need of it.

Currently I own various prime lenses. I also have the Sigma 18-35mm f1.8 which I rate highly. For a drama or documentary shoot with my FS7 right now I would probably pack my 18-35mm Sigma, 20mm Sigma, my 14, 35, 55 and 85mm Samyangs plus the 16-300mm Tamron. I could see the Fujinon 18-55mm replacing ALL of the lenses below the 85mm Samyang, except perhaps the 14mm. So instead of carrying 4 lenses, I only need to take one and achieve the same kind of image quality (the Samyangs are T1.4, but normally I stop them down to T2 -T2.8 as they are a bit soft wide open). I will have less breathing, plus I can zoom during the shot. In addition I’m getting near prime lens quality without the need to keep swapping lenses when I need a different focal length.

The Fujinon is light and compact a big bonus when travelling. Once the MK50-135mm becomes available the pair would cover the majority of drama or short film focal lengths. Just 2 light and compact lenses. For me the Sony at f4 just isn’t quite fast enough for film style productions – great for run and gun and general purpose shoots but it’s not really the lens I want.

The only question that remains is what should I get for my F5 with it’s PL/FZ mount? If only the MK18-55mm would fit the F5. Have to save my pennies for the Fujinon XK6x20 20-120mm.

 

PXW-FS5 Native ISO’s

This is as much for my benefit as yours as I can never remember what the native ISO (0dB) is for each of the gamma curves in the FS5.

Standard 1000 ISO
Still 800 ISO
Cinegamma 1  800 ISO
Cinegamma 2  640 ISO
Cinegamma 3  1000 ISO
Cinegamma 4  1000 ISO
ITU709 1000 ISO
ITU709(800) 3200 ISO
S-Log2 3200 ISO
S-Log3 3200 ISO

Using dB and setting it to 0dB really is so much easier with this camera!

The new Sony FS7 zoom lens, the Sony SELP18110G.

AJC03714-1024x681 The new Sony FS7 zoom lens, the Sony SELP18110G.
Sony SELP18110G servo zoom lens.

When Sony launched the FS7 II they also launched a new lens to go along with it. The previous zoom lens that was bundled with the FS7 was the SELP28135G, a 28-135mm f4 zoom lens that would work with Super 35mm, APS-C and full frame cameras. While generally well received this lens is not without it’s problems. For a start it’s not really wide enough for use as a general purpose lens on an APS-C or Super 35mm sensor. The other problem is that the zoom is very slow. Even when set to manual zooming in and out takes a long time. You turn the zoom ring and then have to wait for the lens to catch up.

The new lens is a wider 18mm to 110mm f4 lens. This is a really useful zoom range for a Super 35mm camera. But the new lens can only be used on S35mm and APS-C cameras. It can’t be used with full frame cameras like the A7s in full frame mode.

AJC03718-1024x681 The new Sony FS7 zoom lens, the Sony SELP18110G.
The front element of the Sony SELP18110G.

But what about the zoom speed? Well this has been addressed too. On the 28-135mm lens the zoom function is electronic. There is no mechanical connection between the zoom ring and the optics of the lens. The 18-110 has a proper mechanical connection between the zoom ring and the internal lenses, so now you can crash zoom in and out as fast as you want. In addition the zoom servo motor is much faster and motorised zooms take place much more rapidly. One downside to this is that it’s a bit harder to control the zoom speed. You can do slow creeping zooms if you are very careful with the cameras zoom rocker, but it’s hard to do. The difference in pressure on the zoom rocker between creeping zoom and medium speed is tiny. The lens tended to change zoom speed quite quickly. While it is indeed very nice to have a variable speed motorised zoom, don’t expect the fine degree of control that you get from admittedly more expensive traditional ENG lenses. Lets face it this lens is only around £3K/$5K which is remarkable cheap for a parfocal s35mm zoom. Take a look at the video below for an idea of the zoom speeds etc.

Is it really parfocal? Well yes, it does seem to be parfocal. I only had the lens for a morning to play with, but in all my tests the focus remained constant throughout the zoom range.

So, what about focus? Like the 28-135mm lens there is a nice big focus ring that slides fore and aft.

AJC03723-e1487017741838 The new Sony FS7 zoom lens, the Sony SELP18110G.
Focus, zoom and iris rings on the SELP18110G.

In the rear position the focus is manual and there are calibrated focus markings and end stops. You get about 180 degrees of focus travel from 0.95m (3.1ft) to infinity (in autofocus you can focus slightly closer when the lens is at the wide end). The focus ring has 0.8mm pitch teeth for use with most standard follow focus units, although this gear ring is very close to the end of the lens, so it may be tricky to use if you have a matte box in place. Breathing is very well controlled and barely noticeable unless going through very large focus throws. Out of focus Bokeh isn’t bad either, I didn’t observe any nasty surprises in the limited time I had to play with the lens.

Bokeh-1024x576 The new Sony FS7 zoom lens, the Sony SELP18110G.
Frame Grab. Near and far out of focus bokeh is reasonable on the Sony SELP18110G. Click on the image to view a full size copy.

Sharpness and flare. The lens appears to be nice and sharp at the wide end but just a touch soft at the long end. It’s not bad overall but when shooting at 4K I could just about detect the lens becoming marginally softer as I zoomed in. The sample I had was a well used pre-production prototype, but I’m going to guess that the production lenses won’t be hugely different. Shooting the roof of a house against a bright sky revealed only a small amount of flare, certainly nothing out of the unusual for a zoom lens.

18110-110-1024x576 The new Sony FS7 zoom lens, the Sony SELP18110G.
Frame grab from the Sony SELP18110G at 110mm. Click on the image to view a full size copy.
18110-18-1024x576 The new Sony FS7 zoom lens, the Sony SELP18110G.
Frame grab shot with Sony SELP18110G at 18mm. Click on the image to view the full size image.

Overall I really like this lens. It even has a support point at the front of the lens body for additional stability. While f4 isn’t the largest of apertures it is quite usable and even wide open the lens performs well. For the money it is a lot of lens. I think we need to be realistic with our expectations for zoom lenses and large sensors. Bigger zoom ratios require bigger lens elements if we want to maintain a constant aperture. Bigger lens elements cost more to produce.

AJC03729-e1487018834354 The new Sony FS7 zoom lens, the Sony SELP18110G.
Underside of the Sony SELP18110G showing the extra lens support points. A lens foot that attaches to the rear mounting is included with the lens.

One advantage Sony have over the competition is that it’s easier to make zoom lenses for the very short flange back distance of the E-Mount cameras compared to the deeper flange back of PL or Canon mounts. The closest competition to this lens is the Canon 18-80mm T4.4 (f4 ish) which is a fair bit more expensive (£4K/$6K). If you want a similar zoom range then you’re looking at the beautiful  Fujinon 20-120 T3.4 at around £14K/$19K.

Northern Colour – new Northern Lights video.

It’s that time of year again. After another simply amazing trip to northern Norway I am pleased to be able to share with you my latest Aurora video. It was shot with a Sony A7s and a Sony A6300. The lenses used were a Sigma 20mm f1.4 art lens. An older Sigma 20mm f1.8, a samyang 14mm f2.8 and a Sony 16mm f2.8 pancake lens. A Metabones Speedbooster Ultra was used on the A6300. For the slider shots I used a home built track (made so it fits my suitcase perfectly) and a Cinetics Cinemoco controller. Hope you enjoy it.

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

Norway and the Northern Lights Video Blogs.

I produced 3 video blogs during my trip to Norway to shoot the northern lights. These blogs are now on youtube for you to watch. In the first video I take a look at some of the equipment that I took to Norway for the trip. I also look at how I like to lay everything out before I pack it and give some insight into some of the accessories that I like to take.

The second video looks back at the first week of the trip. You will see examples of the weather we had to deal with as well as some information on how some of the time lapse sequences of the aurora were shot.

The third video is about shooting a sunrise with 3 different cameras. The Sony a6300, FDR-AX3000 Action Cam and the PXW-FS5.
Packing for the shoot.

At the bottom of the page you’ll find a quick cut of a small selection of some of the Aurora footage shot on this trip.

Review of the first week in Norway.

Shooting a sunrise with 3 different cameras.

Quick sample of some of the Aurora footage:

Norway here I come!

Today I leave for my annual Northern Lights expeditions. So, I am off to the very north of Norway to shoot in the cold, long nights of the arctic winter. Currently sunrise is at 11am and sunset at about 12:30. You get golden hour all day and then a very long night (fully dark from about 3:30pm). If the weather gods are kind we will get clear skies and lots of opportunities to photograph and video the Northern Lights.

Over the next 3 weeks I will be releasing a number of video blogs about this adventure. They won’t be every day as I won’t always have internet access and the picture quality of the blogs may not be the best. But what I hope to cover are some of the practical aspects of a project like this. The first blog is about the equipment I’m taking, why I’ve chosen it and how I like to check what I’m packing.

There will be videos on shooting time-lapse, tips for shooting in the cold and more about the gear I’m using.

Here’s the first video: Packing.