With Sony’s log capable cameras (and most other manufacturers) when you switch between the standard gamma curves and log gamma there is a change in the cameras ISO rating. For example the FS7 is rated at 800 ISO in rec709 but rated at 2000 ISO in log. Why does this change occur and how does it effect the pictures you shoot?
As 709 etc has a limited DR (between around 6 and 10 stops depending on the knee settings) while the sensor itself has a 14 stop range, you only need to take a small part of the sensors full range to produce that smaller range 709 or hypergamma image. That gives the camera manufacturer some freedom to pick the sweetest part of the sensors range. his also gives some leeway as to where you place the base ISO.
I suspect Sony chose 800 ISO for the FS7 and F5 etc as that’s the sensors sweet spot, I certainly don’t think it was an accidental choice.
What is ISO on an electronic camera? ISO is the equivalent sensitivity rating. It isn’t a measure of the cameras actual sensitivity, it is the ISO rating you need to enter into a light meter if you were using an external light meter to get the correct exposure settings. It is the equivalent sensitivity. Remember we can’t change the sensor in these cameras so we can’t actually change the cameras real sensitivity, all we can do is use different amounts of gain or signal amplification to make the pictures brighter or darker.
When you go switch the camera to log you have no choice other than to take everything the sensor offers. It’s a 14 stop sensor and if you want to record 14 stops, then you have to take 100% of the sensors output. The camera manufacturer then chooses what they believe is the best exposure mid point point where they feel there is an acceptable compromise between noise, highlight and lowlight response. From that the manufacture will get an ISO equivalent exposure rating.
If you have an F5, FS7 or other Sony log camera, look at what happens when you switch from rec709 to S-Log2 but you keep your exposure constant.
Middle grey stays more or less where it is, the highlights come down. White will drop from 90% to around 73%. But the ISO rating given by the camera increases from 800ISO to 2000ISO. This increased ISO number implies that the sensor became more sensitive – This is not the case and a little missleading. If you set the camera up to display gain in dB and switch between rec709 (std gamma) and S-Log the camera stays at 0dB, this should be telling you that there is no change to the cameras gain, no change to it’s sensitivity. Yet the ISO rating changes – why?
The only reason the ISO number increases is to force us to underexpose the sensor by 1.3 stops (relative to standard gammas such as rec709 and almost every other gamma) so we can squeeze a bit more out of the highlights. If you were using an external light meter to set your exposure if you change the ISO setting on the light meter from 800 ISO to 2000 ISO the light meter will tell you to close the aperture by 1.3 stops. So that’s what we do on the camera, we close the aperture down a bit to gain some extra highlight range.
But all this comes at the expense of the shadows and mid range. Because you are putting less light on the sensor if you use 2000 ISO as your base setting the shadows and mids are now not as good as they would be in 709 or with the other standard gammas.
This is part of the reason why I recommend that you shoot with log between 1 and 2 stops brighter than the base levels given by Sony. If you shoot 1 stop brighter that is the equivalent to shooting at 1000 ISO and this is closer to the 800 ISO that Sony rate the camera at in standard gamma. Shooting that bit brighter gives you a much better mid range that grades much better.
So here it finally is. Sony’s latest digital cinema camera and finally it has a name rather than a number and it’s called Venice.
I was lucky enough to be involved with Venice during the filming of the UK promo film, so I have had a little bit of a chance to play with one, seen it in action in the hands of an experienced DP (Ed Wild B.S.C.) and I have copies of the footage from it (I did the BTS film). So I have a pretty good idea of what we are dealing with…… and it’s good, it’s very, very good.
For a long time I have been saying that what we need is better pixels, not more pixels and that’s precisely what Sony have delivered in Venice. The newly developed sensor is a full frame sensor, 36mm x 24mm with 6K’s worth of horizontal pixels. This means that if you use the camera as a super 35mm camera you have 4K (and for the demo films the pre production cameras used only worked at 4K, the equivalent of 35mm 4 perf. 6K will come a little later). Venice will be able to do a huge range of resolutions and aspect ratios including Anamorphic.
Why only 6K? Well it’s down to pixel size. Bigger pixels can capture more light and they can also store more electrons before they overload. This means you get a bigger dynamic range than would typically be possible with smaller pixels. The extra light capturing capability can be used in one of 2 ways, to increase sensitivity or to decrease noise. It appears that the engineers behind Venice went for the latter, lower noise.
A lot of research was done for this camera. Engineers from Japan met with many ASC and BSC cinematographers. They talked to post houses and colourists to find out what was really needed. I know that Claudio Miranda A.S.C. played an important part in the development process, he also shot the US demo film. The end result is a pretty sensitive camera (500 ISO) with very low noise and over 15 stops of dynamic range. Yes – that’s right over 15 stops without resorting to double exposures or any other tricks!!
While the sensor isn’t a global shutter sensor it does have an extremely fast readout rate. This extra fast readout means that jello and other rolling shutter artefacts are minimised to the point where it behaves much more like a global shutter sensor. Generally speaking, the extra memory circuits needed to get a global shutter either add noise, reduce sensitivity or reduce dynamic range. So it’s not a huge surprise to see the fast read out approach. There was quite a bit of filming done with a rather lovely Lamborghini Uraco, both hand held inside the car and mounted on the front of the car. Looking at the rushes there is no sign of any noticeable rolling shutter artefacts, even the trees flashing past in the background are still nice and vertical.
A lot of the car shooting took place at dusk and an interesting thing that came out of the UK demo reel shoot was how well it performed in low light. The 500 ISO rating is deceptive, because the camera produces so little noise you can rate the camera at a higher ISO and still get good results. Most current cinema cameras don’t produce the best results unless you rate them lower than their base ISO’s. Venice is different, the base ISO is very low noise and very high dynamic range. There appears to be little need to rate it lower for even less noise, although you could if you wish. I asked Ed Wild about this and he was really pleased with Venice’s ISO rating commenting that he often had to rate cameras from other manufacturers lower than the base ISO while he felt Venice at 500 ISO worked really well and that he would even consider rating it higher if needed.
Having a low base ISO means there is less need to use large amounts of ND on outdoor shoots. But talking of ND filters one of the great features of Venice is an 8 stage, behind the lens glass ND filter system. This allows you to choose just the right amount of ND for the light levels you have with no loss of quality. During the pre-shoot test and prep day at Pinewood each stage of the ND was carefully tested for colour shifts and accuracy, no problems were found.
The lens mount on a Venice camera can be changed. It’s not a quick release mount as on the F55 or F5 cameras. It’s normally a PL mount. But the PL mount can be removed and the camera changed to a Sony E-Mount. 6 bolts remove the PL mount and a locking E mount similar to the one on the FS7 II is on the cameras body. This opens up the possibility of using a huge range of lenses, practically anything in fact as it’s easy to adapt from E-Mount to other mounts such as Canon EF for example. For the UK demo reel XTAL Anamorphics from MovieTec were used. Ultra Primes were used for the US promo film.
VENICE A Truly Modular Camera.
Not only can the lens mount be changed but the entire front part of the camera can be changed by removing just 4 screws. Venice is built as a modular camera and the front part of the camera that contains the sensor and ND filters is a removable module (no need for lab conditions or clean rooms to remove the module). This means that in the future Sony could release new sensor options for Venice. Maybe a higher resolution sensor, a monochrome sensor or a high speed sensor. Removing the front sensor module from the camera allows easy access to the cameras internal near silent fan so that it can be cleaned or replaced should that become necessary. All of the cameras electronics are in sealed compartments for dust and moisture protection and rubber seals are installed around any openings such as the SxS card access door. In addition if you do use the AXS-R7 recorder to record Raw/X-OCN this too is weather sealed.
Venice records to SxS cards and with the AXS-R7 attached to AXS cards. You can record XAVC, ProRes HD, ProRes Proxy, as well as Raw/X-OCN. The XAVC recording option allows you to record direct to compact but high quality ready to go files or to record lower resolution proxy files. X-OCN gives a 16 bit linear workflow with raw type performance but without massive files. There is very little difference between X-OCN and Sony 16 bit linear raw and different versions of X-OCN work at different bit rates so you can pick and choose the right balance of image quality against file size for each project.
For Venice Sony have developed new colour science that is designed to emulate film. Looking at the rushes from the camera it really looked nice without any grading. The images contain lots of lush colours. You could see amazing subtle tonal information in the leaves and trees in the shots. Skin tone highlights roll of in a particularly pleasing way.
One of the biggest criticisms of the PMW-F55 and F5 cameras when they were launched was that they were too complex to drive. The F55 menu system is very large containing many, many pages of settings and adjustments. This is a cinema camera without a lot of the fancy modes that cameras like the F5 or F55 have so the menus are simpler straight away. A lot of time was spent trialling different menu structures to determine the easiest and friendliest structure. At the press event during the hands on session most people found it quite easy to navigate around the menus. But really the way the side panel and the quick menu is set up means you won’t need to dive into the main menu very often.
The camera body is a bit bigger than an F55/F5 and a lot smaller and lighter than an F65. On the right side of the camera there is the main LCD display, which is very similar to the one on the F55/F5 with 6 hot keys around it and a rotary menu dial. This is actually quite similar to the F55’s new Quick Menu system and easy to master. All the key functions and setup options are just a couple of button presses away. This is the main display and where most of the cameras settings can be changed. It’s on the right side so the AC or DIT can get at it and see it easily. Pressing the user button turns 5 of the 6 buttons around the LCD into user assignable buttons (the 6th button is used to set the assignable functions).
On the left side of the camera there is a small information display that shows the frame rate, shutter speed, ND, ISO and white balance.
The white balance of the camera can be dialled in manually unlike the F55 you are no longer tied to 3 presets. You can now dial in the white balance you want down to 1 kelvin increments. Once you have set your white balance you can include your new custom setting in the preset list for quick recall at any time.
The camera can run off either 12V or 24V and it has an internal 24V inverter so that when using a 12V power source such as a V-Mount battery you still get 24V out of the industry standard 24V lemo connectors.
Venice is a modular camera system with various upgrade options. The base camera comes as a 4K super 35mm camera. the 6K option, anamorphic options (6K full frame and 4K 35mm) and other options will be available as option licences. These licences can be purchased as weekly, monthly or permanent options depending on your needs.
What about the picture? I spent a couple of days looking at footage from this camera both in my own grading suite and at Sony’s Pinewood facility during the production of the BTS film. I also saw it projected at the press day and it looks good. One problem today is that there are so many very good and very capable cameras that it’s tough to really pinpoint things that make one stand out as better than another. What I have found to be very pleasing from Venice is the skin tones. Sony have introduced new colour science and colour management for Venice and I think it looks really good. Even before grading, just looking at the clips on a monitor with S-Log3 gamma the pictures have a wonderful rich look. It’s worth noting that the cameras used for both the US and EU launch films were hand made pre-production units and the engineers are still learning how to fully exploit the new sensors in these cameras. So we can only expect them to get better between now and when they become available to buy.
Will I be getting one? Probably not. This is a wonderful camera and I would love to own one, but Venice will be more expensive than the F55 and probably not the best investment for me at least. However I fully intend to get my grubby fingers on one as soon as possible to learn all of it’s in’s and out’s as I hope to use a Venice for some short films I have planned. This is a serious Alexa or Red alternative It has image quality to rival or better almost any other digital cinema camera, but that does come at a price, although it’s no more expensive than any other comparable camera.
The estimated price for the base camera is expected to be around €37,000. Full frame and anamorphic options will be payable options, with the full-frame option costing a approx €4,000 and the anamorphic costing a approx €6,000. it should be available from around February 2018.
I’ve been shooting with the Fujinon MK18-55mm lens on my PXW-FS7 and PXW-FS5 since the lens was launched. I absolutely love this lens, but one thing has frustrated me: I really wanted to be able to use it on my PMW-F5 to take advantage of the 16 bit raw. Finally my dreams have come true as both Duclos and MTF have started making alternate rear mounts for both the MK18-55mm and the MK50-135mm.
So, when Fujinon contacted me and asked if I would be interested in shooting a short film with these lenses on my F5 I jumped at the chance. The only catch was that this was just over a week ago and the video was wanted for IBC which means it needed to be ready yesterday. And of course it goes without saying that it has to look good – no pressure then!
First challenge – come up with something to shoot. Something that would show off the key features of these beautiful lenses – image quality, weight, macro etc. I toyed with hiring a model and travelling to the Irish or Welsh coast and filming along the cliffs and mountains. But it’s the summer holidays so there was a risk of not being able to get an isolated location all to ourselves, plus you never know what the weather is going to do. In addition there was no story, no beginning, middle or end and I really wanted to tell some kind of story rather than just a montage of pretty pictures.
So my next thought was to shoot an artist creating something. I spent a weekend googling various types of artistry until I settled on a blacksmith. The video was going to be shown in both SDR and HDR and fire always looks good in HDR. So after dozens of emails and telephone calls I found an amazing looking metalwork gallery and blacksmith that was willing for a reasonable fee to have me and another cameraman take over their workshop for a day (BIG thank you to Adam and Lucy at Fire and Iron check out their amazing works of art).
Normally I’d carry out a recce of a location before a shoot to take photos and figure out what kind of lights I would need as well as any other specialist or unusual equipment. But this time there simply wasn’t time. We would be shooting the same week and it was already a very busy week for me.
The next step before any shoot for me is some degree of planning. I like to have a concept for the video, at the very least some outline of the shots I need to tell the story, perhaps not a full storyboard, but at least some kind of structure. Once you have figured out the shots that you want to get you can then start to think about what kind of equipment you need to get those shots. In this case, as we would be shooting static works of art I felt that having ways to move the camera would really enhance the video. I have a small Jib as well as some track and a basic dolly that is substantial enough to take the weight of a fully configured PMW-F5 so these would be used for the shoot (I’m also now looking for a slider suitable for the F5/F55 that won’t break the bank, so let me know if you have any recommendations).
So the first items on my kit list after the camera and lenses (the lenses were fitted with Duclos FZ rear mounts) was the jib and dolly. To achieve a nice shallow depth of field I planned to shoot as close to the lenses largest aperture of T2.9 as possible. This presents 2 challenges. The F5’s internal ND filters go in 3 stop steps – that’s a big step and I don’t want to end up at T5.6 when really I want T2.9, so 1 stop and 2 stop ND filters and my gucchi wood finished Vocas matte box would be needed (the wood look does nothing to help the image quality, but it looks cool). Oh for the FS7 II’s variable ND filter in my F5!
The second problem of shooting everything at T2.9 with a super 35mm sensor is that focus would be critical and I was planning on swinging the camera on a jib. So I splashed out on a new remote follow focus from PDMovie as they are currently on offer in the UK. This is something I’ve been meaning to get for a while. As well as the remote follow focus I added my Alphatron ProPull follow focus to the kit list. The Fujinon MK lenses have integrated 0.8 pitch gears so using a follow focus is easy. I now wish that I had actually purchased the more expensive PDMovie follow focus kit that has 2 motors as this would allow me to electronically zoom the lens as well as focus it. Oh well, another thing to add to my wish list for the future.
One other nice feature of the Fujinon MK’s is that because they are parfocal you can zoom in to focus and then zoom out for the wider shot and be 100% sure that there is no focus shift and that the image will be tack sharp. Something you can’t do with DSLR lenses.
Lighting: This was a daylight shoot. Now I have to say that I am still a big fan of old school tungsten lighting. You don’t get any odd color casts, it gives great skin tones, it’s cheap and the variety and types of lamp available is vast. But as we all know it needs a lot of power and gets hot. Plus if you want to mix tungsten with daylight you have to use correction gels which makes the lights even less efficient. So for this shoot I packed my Light and Motion Stella lamps.
The Stellas are daylight balanced LED lamps with nice wide 120 degree beams. You can then use various modifiers to change this. I find the 25 degree fresnel and the Stella 5000 a particularly useful combination. This is the equivalent to a 650W tungsten lamp but without the heat. The fresnel lens really helps when lighting via a diffuser or bounce as it controls the spill levels making it easier to control the overall contrast in the shot. The Stella lights have built in batteries or can be run from the mains. They are also waterproof, so even if it rained I would be able to have lights outside the workshop shining in through the windows if needed.
I always carry a number of pop-up diffusers and reflectors of various sizes along with stands and arms specifically designed to hold them. These are cheap but incredibly useful. I find I end up using at least one of these on almost every shoot that I do. As well as a couple of black flags I also carry black drapes to place on the floor or hang from stands to reduce reflections and in effect absorb unwanted light.
To check my images on set I use an Atomos Shogun Flame. Rather than mounting it on the camera, for this shoot I decided to pack an extra heavy duty lighting stand to support the Shogun. This would allow my assistant to use the flame to check focus while I was swinging the jib. The HDR screen on the Shogun allows me to see a close approximation of how my footage will look after grading. It also has peaking and a zoom function to help with focussing which was going to be essential when the camera was up high on the jib and being focussed remotely. I also included a TV-Logic LUM171G which is a 17″ grading quality monitor with 4K inputs. The larger screen is useful for focus and it’s colour accuracy helpful for checking exposure etc.
For audio I packed my trusty UWP-D wireless mic kit and a pair of headphones. I also had a shotgun mic and XLR cable to record some atmos.
As well as all the larger items of kit there’s also all the small bits and bobs that help a shoot go smoothly. A couple of rolls of gaffer tape, crocodile clips, sharpies, spare batteries, extension cables etc. One thing I’ve found very useful is an equipment cart. I have a modiffied rock-n-roller cart with carpet covered shelves. Not only does this help move all the kit around but it also acts as a desk on location. This is really handy when swapping lenses or prepping the camera. It can save quite a bit of time when you have a mobile work area and somewhere you can put lenses and other frequently used bits of kit.
The day before the shoot I set everything up and tested everything. I checked the backfocus adjustment of the lenses. Checked the camera was working as expected and that I had the LUT’s I wanted loaded into both the camera and the Gratical viewfinder. With the camera on the jib I made sure I had the right weights and that everything was smooth. I also checked that my light meter was still calibrated against the camera and that the lens apertures matched what I was expecting (which they did perfectly). Color temperature and colorimetry was checked on the TVLogic monitor.
It’s worth periodically checking these things as there would be nothing worse than rocking up for the shoot only to find the camera wasn’t performing as expected. If you rent a cinema camera package from a major rental house it would be normal to set the camera up on a test bench to check it over before taking it away. But it’s easy to get lazy if it’s your own kit and just assume it’s all OK. A full test like this before an important shoot is well worth doing and it gives you a chance to set everything up exactly as it will be on the shoot saving time and stress at the beginning of the shoot day.
On the morning of the shoot I loaded up the car. I drive a people carrier (minivan to my friends in the USA). Once you start including things like a jib, track and dolly, equipment cart, 6x tungsten lights, 4 x LED lights, plus camera, tripods (including a very heavy duty one for the jib) the car soon fills up. A conventional saloon would not be big enough! One word of caution. I was involved in a car crash many years ago when the car rolled over. I had camera kit in the back of the car and the heavy flight cases did a lot of damage crashing around inside the car. If you do carry heavy kit in the car make sure it’s loaded low down below the tops of the seats. You don’t want everything flying forwards and hitting you on the back of your head in a crash. Perhaps consider a robust steel grill to put between the cargo compartment and the passenger compartment.
On arrival at the location, while it’s very tempting to immediately start unloading and setting up, I like to take a bit of a break and have a tea or coffee first. I use this time to chat with the client or the rest of the crew to make sure everyone knows what’s planned for the day. Taking a few minutes to do this can save a lot of time later and it helps everyone to relax a little before what could be a busy and stressful day.
Now it’s time to unpack and setup. I find it’s better to unpack all the gear at this time rather than stopping and starting throughout the day to unpack new bits of kit. Going to the car, unlocking, unpacking, locking, back to the set etc wastes time. This is where the equipment cart can be a big help as you can load up the cart with all those bits and pieces you “might” need… and inevitably do need.
The blacksmiths workshop was a dark space about 6m x 5m with black walls, open on one side to the outside world. Blacksmiths forges (so I learnt) are dark so that the blacksmith can see the glow of the metal as it heats up to gauge it’s temperature. On the one hand this was great – huge amounts of relatively soft light coming from one direction. On the other hand the dark side was very dark which would really push the camera and lenses due to the extreme contrast this would create.
We set the jib up inside the workshop to shoot the various processes used by a blacksmith when working with iron and steel. Apparently there are only 7 different processes and anything a blacksmith does will use just these 7 processes or variations of them.
Most of the shots done on the jib would be shot using the Fujinon MK18-55mm, so that’s the lens we started with. For protection from flying sparks a clear glass filter was fitted to the lens. While the finished film would be a 24p film, most of the filming was 4K DCI at 60fps recording to 16 bit raw. This would give me the option to slow down footage to 24p in post if I wanted a bit of slow motion.
When we did need to do a lens swap it was really easy. The Vocas matte box I have is a swing-away matte box. So by releasing a lever on the bottom of the matte box it swings out of the way of the lens without having to remove it from the rods. Then I can remove the lens and swap it to the other lens. The MK50-135mm is the same size as the MK18-55mm. The pitch gears are also in the same place. So swapping lenses is super fast as the follow focus or any focus motors don’t need to be re-positioned and the matte box just swings back to exactly the same position on the lens. It’s things like this that really separate pro cinema lenses from DSLR and photography lenses.
For exposure I used the cameras built in LUT’s and the 709(800) LUT. I set the camera to 800EI. I used a grey card to establish a base exposure, exposing the grey card at 43% (measuring the 709 level). I used a Zacuto Gratical viewfinder which has a great built in waveform display, much better than the one in the camera. I also double checked my light levels with a light meter. I don’t feel that it’s essential to use a light meter but it’s a useful safety net. The light meter is also handy for measuring contrast ratios across faces etc but again if you have a decent waveform display you don’t have to have a light meter.
For the next 3 hours we shot the various processes seen in the video. Trying to get a variety of different shot. But when each process is quite similar, usually involving the anvil and a large hammer it was difficult to come up with shots that looked different.
In the afternoon we set up to shoot the interview sequence. The reason for doing this was to not only provide the narrative for the film but also to help show how the lenses reproduce skin tones. The Fujinon MK series lenses are what I would describe as “well rounded”. That is, not too sharp but not soft either. They produce beautifully crisp pictures without the pictures looking artificially sharp and this really helps when shooting people and faces. They just look really nice.
For the interview shot I used one of the Stella 5000 lights with the 25 degree fresnel lens aimed through a 1m wide diffuser to add a little extra light to supplement the daylight. This allowed me to get some nice contrast across the blacksmiths face and nice “catch light” highlights in his eyes. In addition the little bit of extra light on his face meant that the back wall of the forge would appear just that bit darker due to the increased contrast between his face and the back wall. This is why we light…. not just to ensure enough light to shoot with, I had plenty of light, if I remember right I had a 1 stop ND in the matte box. But to create contrast, it’s the contrast that gives the image depth, it’s contrast that makes an image look interesting.
The final stage was to shoot the treasure chest and ornate jars that would show off the the lenses macro and close up performance. The treasure chest is a truly amazing thing. It weighs around 80kg. The locking mechanism is quite fascinating and I still struggle to believe that it was all hand made. The small metal jars are made out of folded and welded steel. It’s the folds in the metal that create the patterns that you see.
Once again we used the jib to add motion to the shots. I also used the macro function of both the MK18-55mm and MK50-135mm lenses. This function allows you to get within inches of the object that you are shooting. It’s a great feature to have and it really adds to the versatility of these lenses.
We wrapped at 7pm. Time to pack away the kit. It’s really important not to rush at this stage. Like everyone else I want to get home as quick as I can. But it’s important to pack your kit carefully and properly. There is nothing more annoying than when you start prepping for the next shoot finding that something has been broken or is missing because you rushed to pack up at the end of the previous shoot. Once you have packed everything away don’t forget to do that last walk through all the locations you’ve shot in to make sure you haven’t forgotten something.
I shot a little over hour of material. As it was mostly 60p 4K raw that came to about 1.5TB This was backed up on site using a Nexto-DI NSB25 which is a stand alone device that makes 2 verified copies of everything on 2 different hard drives. The film was edited using Adobe Premiere CC which handles Sony’s raw very easily. Grading was completed using DaVinci Resolve. I spent 2 days editing and a day grading the first version of the film. Then I spent another day re-grading it for HDR and producing the different versions that would be needed. All in, including coming up with the concept, finding the location, prepping, shooting and post took it took about 7 to 8 full work days to put this simple 4 minute film together.
I have been asked whether you should still expose log a bit brighter than the recommended base levels on the Sony PXW-FS5 now that Sony have released new firmware that gives it a slightly lower base ISO. In this article I take a look at why it might be a good idea to expose log (with any camera) a bit brighter than perhaps the manufacturer recommends.
There are a couple of reasons to expose log nice and bright, not just noise. Exposing log brighter makes no difference to the dynamic range. That’s determined by the sensor and the gain point at which the sensor is working. You want the camera to be at it’s native sensitivity or 0dB gain to get that maximum dynamic range.
Exposing brighter or darker doesn’t change the dynamic range but it does move the mid point of the exposure range up and down. Exposing brighter increases the under exposure range but decreases the over exposure range. Exposing darker decreases the under exposure range but increases the over exposure range.
Something that’s important when thinking about dynamic range and big dynamic ranges in particular is that dynamic range isn’t just about the highlights it’s also about the shadows, it isn’t just over exposure, it’s under exposure too, it’s RANGE.
So why is a little bit of extra light often beneficial? You might call it “over exposure” but that’s not a term I like to use as it implies “too much exposure”. I prefer to use “brighter exposure”.
It’s actually quite simple, it’s about putting a bit more light on to the sensor. Most sensors perform better when you put a little extra light on them. One thing you can be absolutely sure of – if you don’t put enough light on the sensor you won’t get the best pictures.
Put more light on to the sensor and the shadows come up out of the sensors noise floor. So you will see further into the shadows. I’ve had people comment that “why would I ever want to use the shadows, they are always noisy and grainy”? But that’s the whole point – expose a bit brighter and the shadows will be much less noisy, they will come up out of the noise. Expose 1 stop brighter and you halve the shadow noise (for the same shadows at the previous exposure). Shadows are are only ever noise ridden if you have under exposed them.
This is particularly relevant in controlled lighting. Say you light a scene for 9 stops. So you have 9 stops of dynamic range but a 14 stop sensor. Open up the aperture, put more light on the sensor, you get a better signal to noise ratio, less noisy shadows but no compromise of any type to the highlights because if the scene is 9 stops and you have 14 to play with, you can bring the exposure up by a couple of stops comfortably within the 14 stop capture range.
Look at the above diagram of Sony’s S-Log2 and S-Log3 curves. The vertical 0 line in the middle is middle grey. Note how above middle grey the log curves are more or less straight lines. That’s because above the nominal middle grey exposure level each stop is recorded with the same amount of data, this you get a straight line when you plot the curve against exposure stops. So that means that it makes very little difference where you expose the brighter parts of the image. Expose skin tones at stop + 1 or stop +3 and they will have a very similar amount of code values (I’m not considering the way dynamic range expands in the scene you shoot as you increase the light in the scene in this discussion). So it makes little difference whether you expose those skin tones at stop +1 or +3, after grading they will look the same.
Looking at the S-Log curve plots again note what happens below the “0” middle grey line. The curves roll off into the shadows. Each stop you go down has less data than the one before, roughly half as much. This mimics the way the light in a real scene behaves, but it also means there is less data for each stop. This is one of the key reasons why you never, ever want to be under exposed as if you are underexposed you mid range ends up in this roll off and will lack data making it not only noisy but also hard to grade as it will lack contrast and tonal information.
Open up by 1 additional stop and each of those darker stops is raised higher up the recording curve by one stop and every stop that was previously below middle grey doubles the amount of tonal values compared to before, so that’s 8 stops that will have 2x more data than before. This gives you a nice fat (lots of data) mid range that grades much better, not just because it has less noise but because you have a lot more data where you really need it – in the mid range.
Note: Skin tones can cover a wide exposure range, but typically the mid point is around 1 to 1.5 stops above middle grey. In a high contrast lighting situation skin tones will start just under middle grey and extend to about 2 stops over. If you accidentally under expose by 1 stop or perhaps don’t have enough light for the correct exposure you will seriously degrade the quality of your skin tones as half of your skin tones will be well below middle grey and in the data roll-off.
Now of course you do have to remember that if your scene does have a very large dynamic range opening up an extra stop might mean that some of the very brightest highlights might end up clipped. But I’d happily give up a couple of specular highlights for a richer more detailed mid range because when it comes to highlights – A: you can’t show them properly anyway because we don’t have 14 stop TV screens and B: because highlights are the least important part of our visual range.
A further consideration when we think about the highlights is that with log there is no highlight roll-off. Most conventional gamma curves incorporate a highlight roll-off to help increase the highlight range. These traditional highlight roll-offs reduce the contrast in the highlights as the levels are squeezed together and as a result the highlights contain very little tonal information. So even after grading they never look good, no matter what you do. But log has no highlight roll-off. So even the very brightest stop, the one right on the edge of clipping contains just as much tonal information as each of the other brighter than middle grey stops. As a result there is an amazingly large amount of detail than can be pulled out of these very bright stops, much more than you would ever be able to pull from most conventional gammas.
Compare log to standard gammas for a moment. Log has a shadow roll-off but no highlight roll-off. Most standard gammas have a strong highlight roll-off. Log is the opposite of standard gammas. With standard gammas, because of the highlight roll-off, we normally avoid over exposure because it doesn’t look good. With Log we need to avoid under exposure because of the shadow roll-off, it is the opposite to shooting with standard gammas.
As a result I strongly recommend you never, ever under expose log. I normally like to shoot log between 1 and 2 stops brighter than the manufacturers base recommendation.
Next week: Why is a Sony camera like the FS7,F5 800 ISO with standard gamma but 2000 ISO in log and how does that impact the image?
Sony have just released a rather exciting looking new type of mini-cam, the RX0.
I have not played with one yet, so I can only base my comments on the specs, but the specs are both impressive and exciting.
Most gopro type cameras use tiny sensors packed with pixels. This presents a problem as they tend not to be very light sensitive. However those small sensors when combined with an ultra wide angle lens eliminates the need to focus as the depth of field is vast. But for many applications that’s not what you always want. Sometimes you don’t want an ultra wide fisheye view of the world, sometimes you want to get in a bit closer. Sometimes you want a bit of selective focus. In addition it’s hard to be creative when you have no focus or depth of field control. Talking of control most mini-cams have very, very little in the way of manual control as they don’t have adjustable apertures and as a result rely entirely on variable gain and shutter speeds to control the exposure.
Enter the RX0. The RX0 shares a lot of features with the well regarded RX series of compact stills cameras. It has a 1.0″ type sensor, huge compared to most other minicams. It has 24mm f4 lens so it’s less wide and has a shallower DoF. It can shoot in 4K, it can even record using S-Log2 to capture a greater dynamic range so it may turn out to be a great mini-cam for HDR productions (although how big that dynamic range is is not clear at this time). I wish I had some of these for the HDR shoots I did at the beginning of the year.
It’s a camera you can control manually and it even has a special high speed shutter mode for all but eliminating rolling shutter artefacts.
Want to shoot slow-mo? No problem, the maximum frame rate is 960fps (although I suspect that the image quality drops at the higher frame rates).
It’s still very small and very compact, it’s also waterproof and has a high degree of shock proofing.
I can see myself using this as a time lapse camera or in a VR rig. So many applications for a camera like this. Can’t wait to get my hands on one.
Prepping my camera today for a shoot tomorrow. I’ll be shooting with the Fujinon MK18-55mm and MK50-135mm lenses fitted with Duclos FZ mount adapters. I’ve been using the MK18-55mm on my FS7 and FS5 for some time and I have to say I really love this lens. It produces beautiful images with silky smooth bokeh, it’s parfocal and it covers a very hand range of focal lengths. I’ve been wanting to use this lens on my F5 for some time and now at last I can. These lenses work great on the F5 and F55. They are very light compared to most PL lenses and this really helps with the cameras balance, especially if shooting handheld. They are also very cost effective.
The light lens weight means I need less weight on my jib than I would have with most similar PL zoom lenses. Also being nice and fast at T2.9 I know I can get great shallow DoF. Tomorrow I’m going to be shooting 2 amazing artists that create incredibly detailed things out of large lumps of iron and steel. I’ll be shooting examples of some of the finest works of metallic art along with all the key parts of the process of creating them. There will be beauty, iron, steel, heat, flames and sparks. I’ll try to post pictures from the shoot over the weekend and once the video is done it will be online for all to enjoy.
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.
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).
Just a reminder that my guide to shooting with Cine EI for the PMW-F5 and F55 cameras is still just as valid today as it was when I wrote it back in 2013. There have been a few tweaks to the cameras menu here and there, but the principles and basic operation have not changed.
So if you are new to Cine-EI please take a look at the guide. It takes you through how to shoot with Cine EI, which LUT’s to use and how to expose them.
I know many of my readers are planning on travelling to the US and the path of totality to shoot the solar eclipse on the 21st of August.
A couple of words of caution.
First, make sure you never view the sun directly or through an optical viewing device such as a DSLR camera, telescope or lens without covering the lens with a dedicated solar viewing filter.
DON’T try to use sun glasses, welding goggles or conventional ND filters.
Most regular photo ND filters only cut the visible spectrum. Many will pass IR (Infra Red) without much attenuation. When shooting or looking at the sun it’s not just the brightness but also the IR that can damage your eyes or the sensor as this is where most of the heat energy is. So a 16 stop ND might well reduce the brightness of the sun to a useable level for a video camera but may not reduce the damaging IR and heat. This could lead to damage to the cameras own ND filters or the sensor itself.
To look at the sun with your eye’s you MUST use a proper solar filter or solar viewing glasses. This will normally be a silvered reflective filter or film. The silver reflective coating reflects away the harmful and damaging infra red as well as reducing the brightness. If the filters you are using are of the film type, check for pin holes in the film before using them.
On a video camera it is much safer to use IRND filters rather than conventional ND filters if you can or add a good quality IR cut filter in front of the ND filters. Don’t skimp on the filters you use.
Make sure you have enough ND for the camera to use an aperture wider than f11. If you are having to stop down to f11 or f16 you will not be getting the sharpest possible image due to diffraction effects. On cameras with smaller sensors such as 2/3″ or 1/2″ you really want to have the aperture more open than f8 for the best results, so that means you’ll typically need 16 stops of ND!!
Try to avoid screw on filters. Once the moon completely covers the sun you will want to quickly remove the heavy ND filters. Then once the sun comes out from behind the moon you will need to replace the filters very quickly. So use something that allows you to do this quickly and easily. A mattebox with slide in filter trays or magnetically attached filters are a good way to do this.
If shooting with a very long lens to get the sun to fill the frame you will be surprised by how fast the sun will move through the frame. So you will need a really good fluid head to allow you to slowly track the sun without jarring or bumping the shot.
Camera setup, reviews, tutorials and information for pro camcorder users from Alister Chapman.