Once upon a time the meaning of ISO was quite clear. It was a standardised sensitivity rating of the film stock you were using. If you wanted more sensitivity, you used film with a higher ISO rating. But today the meaning of ISO is less clear and we can’t swap our sensor out for more or less sensitive ones. So what does it mean?
ISO is short for International Standards Organisation. And they specify many, many different standards for many different things. For example ISO 3166 is for country codes, ISO 50001 is for energy management.
But in our world of film and TV there are two ISO standards that we have blended into one and we just call it “ISO”.
ISO 5800:2001 is the system used to determine the sensitivity of color negative film found by plotting the density of the film against exposure to light.
ISO 12232:2006 specifies the method for assigning and reporting ISO speed ratings, ISO speed latitude ratings, standard output sensitivity values, and recommended exposure index values, for digital still cameras.
Note a key difference: ISO 5800 is the measurement of the actual sensitivity to light of film. ISO 12232 is a standardised way to report the speed rating, it is not a direct sensitivity measurement.
Within the digital camera ISO rating system there are 5 different standards that a camera manufacturer can use when obtaining the ISO rating of a camera. The most commonly used method is the Recommended Exposure Index (REI) method, which allows the manufacturer to specify a camera model’s EI or base ISO arbitrarily based on what the manufacturer believes produces a satisfactory image. So it’s not really a measure of the cameras sensitivity, but a rating that if used with a standard external calibrated light meter to set the exposure will give a satisfactory looking image. This is very different to a sensitivity measurement and variations in the opinion as to what is a satisfactory image will vary from person to person. So there is a lot of scope for movement as to how an electronic camera might be rated.
As you cannot change the sensor in a digital camera, you cannot change the cameras efficiency at converting light into electrons (which is largely determined by the materials used and the physical construction). So you cannot change the actual sensitivity of the camera to light. But we have all seen how the ISO number of most digital cameras can normally be increased (and sometimes lowered) from the base ISO number.
Raising and lowering the ISO in an electronic camera is normally done by adjusting the amplification of the signal coming from the sensor, typically referred to as “gain” in the camera. It’s not actually a physical change in the cameras sensitivity to light, it like turning up the volume on a radio to make the music louder. Dual ISO cameras that claim not to add gain when switching between ISO’s typically do this by adjusting the way the signal from the sensor is converted from an analog signal to a digital one. While it is true that this is different to a gain shift it does typically alter the noise levels as to make the picture brighter you need to sample the sensors output lower down and closer to the noise floor. Once again though it is not an actual sensitivity change, it does not alter the sensors sensitivity to light, you are just picking a different part of it’s output range.
Noise and Signal To Noise Ratio.
Most of the noise in the pictures we shoot comes from the sensor and the level of this noise coming from the sensor is largely unchanged no matter what you do (some dual ISO cameras use variations in the way the sensor signal is sampled to shift the noise floor up and down a bit). So the biggest influence on the signal to noise ratio is the amount of light you put on the sensor. More light = More signal. The noise remains the same but the signal is bigger so you get a better signal to noise ratio, up to the point where the sensor overloads.
But what about low light?
To obtain a brighter image when there the light levels are low and the picture coming from the sensor looks dark the signal coming from the sensor is boosted or amplified (gain is added). This amplification makes both the desirable signal bigger but also the noise bigger. If we make the desirable picture 2 times brighter we also make the noise 2 x bigger. As a result the picture will be more noisy and grainy than one where we had enough light to get the brightness we want.
The signal to noise ratio deteriorates because the added amplification means the recording will clip more readily. Something that is close to the recordings clip point may be sent above the clip point by adding gain, so the range you can record reduces while the noise gets bigger. However the optimum exposure is now achieved with less light so the equivalent ISO number is increased. If you were using a light meter you would increase the ISO setting on the light meter to get the correct exposure. But the camera isn’t more sensitive, it’s just that the optimum amount of light for the “best” or “correct” exposure is reduced due to the added amplification.
So with an electronic camera, ISO is a rating that will give you the correct brightness of recording for the amount of light and the amount of gain that you have. This is different to sensitivity. Obviously the two are related, but they are not quite the same thing.
Getting rid of noise:
To combat the inevitable noise increase as you add gain/amplification most modern cameras use electronic noise reduction which is applied more and more aggressively as you increase the gain. At low levels this goes largely un-noticed. But as you start to add more gain and thus and more noise reduction you will start to degrade the image. It may become softer, it may become smeary. You may start to see banding ghosting or other artefacts.
Often as you increase the gain you may only see a very small increase in noise as the noise reduction does a very good job of hiding the noise. But for every bit of noise thats reduced there will be another artefact replacing it.
Technically the signal to noise ratio is improved by the use of noise reduction, but this typically comes at a price and NR can be very problematic if you later want to grade or adjust the footage as often you won’t see the artefacts until after the corrections or adjustments have been made. So be very careful when adding gain. It’s never good to have extra gain.
After a test run starting and finishing in Alta last year I have decided to run the trips from Alta again next year. The hotel is nicer and the itinerary more relaxed. Starting and finishing at Alta gives us more time at the cabins.
2017/2018 Northern Lights Expeditions to Norway, travelling by road and snow scooter, staying in mountain cabins. Including food for 4 days, ice fishing, snow scooter use and optional photo/video tuition. You must book your own flights to Alta, Norway.
2018 Tour 1: Arctic Dawn. On this tour we will see the very first sunrise of the year. The moon will be absent during the night, so best suited for shooting and viewing faint Aurora. Arrive Friday 12th January 2018, depart Thursday 18th January 2018. £1,350 per person. Max 8 people. (cost of flights NOT included). You must arrange your own transport to and from Alta, Norway.
2018 Tour 2: Moonrise Tour. On this tour we will have a rising moon (after new moon) The moon will start at 18% illumination and increase to 53% illumination over the course of the tour. This will provide interesting possibilities for moonlit landscapes, but if the Aurora is very, very faint it will be harder to see. The days will be longer during this tour than the first tour. Arrive Thursday 18th of January 2018, Depart Wednesday 24th of January 2018. £1350 per person max 8 guests.
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?
This is a question that comes up time and time again. I’ve been using the F5 and FS7 for almost 5 years. What I’ve discovered in that time is that the one thing that people notice more than anything from these cameras is noise if you get your exposure wrong. In addition it’s much harder to grade a noisy image than a clean one.
Lets take a look at a few key things about how we expose and how the F5/FS7 works (note the same principle applies to most log based cameras, the FS5 also benefits from being exposed brighter than the suggested base settings).
What in the image is important? What will your audience notice first? Mid-range, shadows or highlights?
I would suggest that most audiences first look at the mid range – faces, skin tones, building walls, plants etc. Next they will notice noise and grain or perhaps poor, muddy or murky shadows. The last thing they will notice is a few very brightly highlights such as specular reflections that might be clipped.
The old notion of protecting the highlights comes from traditional gamma curves with a knee or highlight roll off where everything brighter than a piece of white paper (90% white) is compressed into a very small recording range. As a result when shooting with conventional gamma curves ALL of the brighter parts of the image are compromised to some degree, typically showing a lack of contrast and texture, often showing some weird monotone colors. Log is not like that, there is no highlight roll off, so those brighter than white highlights are not compromised in the same way.
In the standard gammas at 0dB the PXW-FS7, like the PMW-F5 is rated at 800 ISO. This gives a good balance between noise and sensitivity. Footage shoot at 0dB/800ISO with the standard gammas or Hypergammas generally looks nice and clean with no obvious noise problems. However when we switch to log the native ISO rating of the cameras becomes 2000 ISO, so to expose “correctly” we need to stop the aperture down by 1.3 stops. This means that compared to 709 and HG1 to HG4, the sensor is being under exposed by 1.3 stops. Less light on the sensor will mean more noise in the final image. 1.3 stops is the equivalent of 9dB. Imagine how Rec709 looks if it is under exposed by 1.3 stops or has to have +9dB of gain added in. Well – thats what log at 2000 ISO will look like.
However log has lots of spare headroom and no highlight compression. So we can choose to expose brighter than the base ISO because pushing that white piece of paper brighter in exposure does not cause it to become compressed.
If you open the aperture back up by 1.3 stops you get back to where you would be with 709 in terms of noise and grain. This would be “rating” the camera at 800 ISO or using 800 EI. Rating the camera at 800EI you still have 4.7 stops of over exposure range, so the only things that will be clipped will in most cases be specular reflections or extreme highlights. There is no TV or monitor in existence that can show these properly, so no matter what you do, they will never be true to life. So don’t worry if you have some clipped highlights, ignore them. Bringing your exposure down to protect these is going to compromise the mid range and they will never look great anyway.
You should also be extremely cautious about ever using an EI higher that 2000. The camera is not becoming more sensitive, people are often misslead by high EI’s into thinking somehow they are capturing more than they really are. If you were to shoot at 4000 EI you will end up with footage 15dB noisier than if you were shooting the same scene using 709 at 800 ISO. That’s a lot of extra noise and you won’t necessarily appreciate just how noisy the footage will be while shooting looking at a small monitor or viewfinder.
I’ve been shooting with the F5 and then the FS7 for almost 5 years and I’ve never found a situation where I going to an EI higher than 800 would have resulted in a better end result. At the same time I’ve seen a lot of 2000 EI footage where noise in the mid range has been an issue, one particular example springs to mind of a high end car shoot where 2000 EI was used but the gloss and shine of the car bodywork is spoilt because it’s noisy, especially the darker coloured cars.
Of course this is just my opinion, based on my own experience, others may differ and the best thing you can do is test for yourself.
Just a reminder to anyone using a viewfinder fitted with an eyepiece, magnifier or loupe not to leave it pointing up at the sun. Every year I see dozens of examples of burnt and damaged LCD screens and OLED displays caused by sunlight entering the viewfinder eyepiece and getting focussed onto the screen and burning or melting it.
It can only take a few seconds for the damage to occur and it’s normally irreversible. Even walking from shot to shot with the camera viewfinder pointed towards the sky can be enough to do damage if the sun is out.
So be careful, cover or cap the viewfinder when you are not using it. Tilt it down when carrying the camera between locations or shots. Don’t turn to chat to someone else on set and leave the VF pointing at the sun. If you are shooting outside on a bright sunny day consider using a comfort shade such as an umbrella or large flag above your shooting position to keep both you and the camera out of the sun.
Damage to the viewfinder can appear as a smudge or dark patch on the screen that does not wipe off. If the cameras was left for a long period it may appear as a dark line across the image. You can also sometimes melt the surround to the LCD or OLED screen.
As well as the viewfinder don’t point your camera directly into the sun. Even an ND filter may not protect the sensor from damage as most regular ND filters allow the infra red wavelengths that do much of the damage straight through. Shutter speed makes no difference to the amount of light hitting the sensor in a video camera, so even at a high shutter speed damage to the cameras sensor or internal ND’s can occur. So be careful when shooting into the sun. Use an IR ND filter and avoid shooting with the aperture wide open, especially with static shots such as time-lapse.
Having done a fair bit of shooting with the new and very nice Fujinon MK 18-55mm E-Mount lens I decided to take a much closer look at the Fujinon Cabrio XK6x20 20 to 120mm T3.5 lens with the servo hand grip.
The price of this lens is very competitive and it can now be found as low as £11K/$16K. Lets not try to pretend that good quality PL mount zooms are cheap, but this is a great price for what is very high quality glass. The 20 to 120mm zoom range is nice and of course it’s truly parfocal there is a back focus adjuster along with macro function.
Like the other similar ENG style PL zooms this lens is quite heavy. The front element of the lens is huge and I’m sure a lot of the weight comes from this big lump of glass. One of the nice things about this lenses baby brother the MK 18-55, is that the 18-55 is really very light, which is great on the smaller cameras like the FS5 or FS7.
The 20-120mm Cabrio exudes quality. The build quality of the lens is wonderful, the witness marks are crisp and well engraved, the servo zoom is silky smooth. The large servo module acts as a handgrip just like traditional ENG lenses and it really comfortable to hold and use this way. But if you don’t need it it can be easily removed leaving the bare bones lens body and saving a little bit of weight. There are the usual 0.8 mod pitch gears on each of the focus zoom and iris rings. Focus ring travel is huge at about 200 degrees and due to the physical size of the lens this is as much as I’d ever want. Even towards infinity there is still a nice range of travel so focussing accurately on distant objects is easy.
But what about the image quality, how does the lens perform in real world situations?
To find out I used it for a shoot in Norway. The shoot was for TV manufacturer Philips. We wanted to obtain some high quality 4K HDR footage to show off the capabilities of a new 4K OLED Ambilight TV. Unfortunately the weather conditions on the shoot were pretty grim most of the time and this made it all the more challenging. But I’m pleased to say that both lenses performed very well despite snow, ice and cold.
One of the great things about having both the high end Cabrio 20-120mm and the budget friendly 18-55mm for the shoot was that the overall look of the images from the FS5 and F5 was the same. Often mixing lenses from different manufacturers results in different looking images giving the colourist more work to do in post. Fujinon now have a range of lenses to suit most budgets from the high end Cabrio 19-90mm T2.9 down through the Cabrio 20-120 T3.5 to the MK 18-55 T2.9.
So what do the images from these lenses look like? I’m afraid I can’t show any of the footage from the Philips shoot yet, I should be able to show it later in the year. Below are a couple of frame grabs to give you an idea of the kind of images you can get. We didn’t shoot the same shots with the F5/XK6x20 and FS5/MK18-55 at the same time, I was the only cinematographer. So I don’t have a side by side comparison from the shoot, but the different scenes shot with each lens/camera combo match really well.
TESTING BOTH LENSES:
In order to better directly compare the two lenses I shot some test shots. The XK6x20 on my F5 and the MK18-55 on my FS7. Both cameras were set to the same settings and hypergamma 3 with the cinema matrix used. The images you will see below have not been touched, this is how they looked straight from the camera. If you click on the picture you should get a link to the full frame 4K image, but do remember this are Jpegs.
I tried to get the same shots with both combinations but you will see some small variations. I apologise for that. To give as fair a comparison as possible I did most of the shots at 20mm and 55mm, but then in addition shot at 18mm on the MK18-55 and 120mm on the XK6X20 so you can see the additional range each lens offers.
First test was of a neighbours Cherry tree in blossom.
The next test was a simple setup shot of a couple of beer bottles on a table with strong sunlight from above and behind to create deep contrast. I wanted to see if either lens showed signs of loosing shadow detail due to the very large, very bright table top introducing flare into the shadows.
My conclusion with the above shots is that there is remarkably little difference between these two lenses. Both perform extremely well. I think the XK6X20 might be marginally sharper at the wide end than the 18-55mm, either that or the slightly better viewfinder of the F5 is allowing me to focus more precisely. In addition I think the bokeh of the more expensive Cabrio is marginally smoother than the 18-55, but again it’s a tiny difference (not as big as the difference in white balance of the two cameras).
Finally a shot of my ugly mug just so you can take a look at some skin tones.
Again very little difference between these lenses which is a good thing. Both perform very well, both produce pleasing images. Sure the XK6X20 20-120mm is more than twice the price of the MK18-55 but then it does offer twice the zoom range and it’s very hard to make fast parfocal lenses with big zoom ranges for large sensors. There will be a companion MK50-135mm lens coming later in the year, so with both the MK lenses you will be able to get the full range of the XK6X20 and a bit more, provided you don’t mind swapping lenses. It’s a tough choice if you have an E-mount Sony camera, which to get? For E-Mount I think the pair of MK lenses will be the way to go. If you have a PL mount camera the XK6X20 has to be a very serious contender. It’s a great all-round cinema zoom lens and a realistic price. Whichever way you do go you won’t be disappointed, these are proper cinema lenses.
I have just return from one of the most challenging shoots I have been involved in. The shoot took place over 5 days in and around Tromso in Norway. The aim was to gather footage to show off the capabilities of a new type of 4K TV from Phillips.
We shot the Northern Lights, we shot dog sledding , snow mobiles, shots of the city and sailing on the fjords. Each part of the shoot had many challenges and a lot of the shoot took place at night and at night the crew slept in cabins, tents and on the yachts. Shooting from the ice and snow covered deck of a yacht in temperatures well below zero is not something I enjoyed. And to top it all off the weather was pretty grim fro most of the shoot. Heavy snow showers, freezing temperatures and towards the end strong winds.
Because image quality is paramount for this project I choses to use the best lenses I could, but at the same time space and time constraints dictated that zoom lenses would be desirable. We were shooting 16 bit raw as well as XAVC class 480 on my PMW-F5 and some pick-up shots in UHD XAVC-L on a PXW-FS5. For the PMW-F5 the primary lens was the Fujinon Cabrio XK6x20, 20-120mm PL zoom and to ensure we had similar looking images from the FS5 I used the new Fujinon XF 18-55mm. I have to say that I’m quite in love with both of these lenses.
The Cabrio 20-120 is a beautiful lens and it’s really nice to have a servo zoom that is truly parfocal. The 20-120 produces really nice images even in the most challenging of conditions and at T3.5 it’s reasonably fast throughout the entire zoom range. This was the lens that I used for the majority of the shoot, in particular for the many night scenes we shot. The E-Mount 18-55 on the FS5 produces images that matched really well with the bigger lens and camera. This is a combination I would love to use on more shoots where the budget will allow.
One particular scene that we had to shoot was particularly challenging. It was a set up shot of a night time arrival of a couple of snowmobiles at a Sami camp site. The Sami people are the indigenous people of Northern Norway and they have a particular style of tent know as a Laavu which is similar to a teepee or wigwam. The idea behind the shot was to have the snow scooters arriving with headlights blazing and for the drivers to then enter the tent lit only by the light of a campfire inside the tent. At the time of the shoot it was snowing heavily and was totally dark. Turn off the lights of the snowmobiles and you could not see a thing.
While modern cameras like the F5 are very sensitive, the light of a campfire inside a tent will not adequately light a scene like this on it’s own. I didn’t want a totally dark background, so I decided that I would subtly light the trees of the forest that we were in to add some drama and give some depth to the background and a sense of being in a forest.
As we were travelling continuously on this shoot there was no space for a large or complex lighting kit and the remote location meant we needed battery powered lights. In addition I knew before we left that there was a chance of bad weather so I needed lights that would work whatever mother nature decided to throw at us.
I decided to take a set of 3 Light & Motion Stella battery powered LED lights. It’s just as well I had the Stella lamps as on top of all the other difficulties of the shoot the weather decided it was not going to play ball. We had to shoot the scene (and much of the shoot) in the middle of a snow storm. Fortunately the Stella lights are completely waterproof, so I didn’t need to worry about rain or snow protection. Just set them up turn them on and use the built in dimmer to set the light output.
To light the scene I set up a Stella Pro 5000 in the woods behind the Sami tent, aimed through the trees and pointed directly towards the camera. I chose to backlight the trees to provide a sense of there being trees rather than lighting them. I felt this would look less lit than throwing a ton of light into the forest from the front and I’m pleased with the result.
The Stella Pro 5000 is very bright for a compact battery operated light, it’s 5000 lumen 120 degree output that is pretty close to what you would get from a 200W HMI, it’s very bright. It has a very high CRI and gives out great quality daylight balanced light. It was positioned so that the light itself was behind the tent on a small bank, about 20m back in the woods. You couldn’t see it in the shot, but the light coming through the trees created shafts of light in the snow and the trees appeared as silhouettes. It added depth and interest to what would have otherwise been a near totally black background.
Then to provide a small amount of light so that we could see the riders of the snow scooters as they walked to the tent I used a Stella 2000. I didn’t really want the light from this lamp to be too obvious as this would really make the scene look “lit”. I didn’t need the full 2000 lumen output so I used the built in dimmer to reduce the output to around 70%.
The third light was a small Stella 1000 and this was placed inside the tent with a scrunched up orange gel. The Stella 1000 would typically be used as a camera top light, but it’s full dimmable and produces a very high light quality, making it suitable for many applications. The creases and folds in the orange gel helped break up the light a little creating a less lit look sympathetic to the fire inside the tent.
It allowed me to increase the illumination in the tent, adding to the light from the fire without it being obvious that the tent interior was lit. For some of the shots I had an assistant sit in the tent, out of shot and slowly move the gel in front of the light to add a little movement to the light to mimic the firelight even better.
At the moment I can’t show you the footage. That will have to wait until after the launch of the TV. But I’m really pleased with the way this scene came out. It’s challenging trying to shoot in the dark, in a blizzard, in temperatures well below freezing. Every aspect of getting this scene was hard. Opening a flight case to get out some kit meant getting snow on everything inside it. Just positioning the light up the woods was tough, the snow was up above my knees as I waded through it. Operating the camera is so much harder when it has a rain cover on it. The viewfinder was constantly misting up as snow fell on it non stop. Seeing the witness marks on the lens is difficult (although thankfully the marks on the Fujinon 20-120 are huge and easy to see).
But sometimes it’s challenges like these that make the job interesting. I know I was cursing and swearing at times trying to make these shots work, but seeing the scene come to life in the grade is all the more rewarding.
I’ll be writing more about the Fujinon 20-120 very soon, so why not subscribe to my blog using the subscribe bottom on the left.
I was recently sent a new rain cover by Camrade for my FS7 (there is also one for the FS7 II). I’ve used Camrade “wet suits” as they call them for years. They are great covers made from a low noise fabric. That means that if you need to fiddle with the cover while shooting it makes very little noise. The fabric is high quality, soft and supple but also completely waterproof.
The FS7 cover set covers the whole camera and lens and also has a separate cover for the viewfinder that can be used either with the extension tube attached or thanks to a large clear panel that allows you to clearly see the LCD screen it can be used without the extension tube. There is also a cover for the arm and handgrip.
The main camera body cover has clear panels that allow you to see all the major controls and switches on both sides. In addition the clear panels can be opened and rolled up and secured open by velcro if you want easy access to the camera while it’s not raining.
Along the top of the cover there is a long velcro opening that allows the mount for the viewfinder to exit the cover as well as an elasticated opening for a shot gun mic. There are further openings for the front MI shoe as well as the cameras top handle.
Overall the cover is quite large and the fit is quite baggy on a bare bones FS7. But this does mean that you can attach radio mic receivers or timecode sync boxes etc to the camera and keep them protected from the elements under the cover. The bagginess also allows you to grip the top handle through the rain cover, so even when carrying the camera from location to location it remains protected from the elements.
The length of the cover means that there is space at the back for the XDCA extension unit and/or an external battery system. There’s even a little flap at the back that allows you to see the top of the battery to check the batter status. This is great with my PAG-Link batteries (love my PAG-Links).
If you are using a long lens then you can add an included extension section to the front of the cover that will protect most lenses. Underneath the main cover there is a zip that allows you to almost completely close the rain cover so that when using the camera on your shoulder it doesn’t flap about.
Cameras like the FS7 are expensive. While the FS7 does have a degree of built in protection against a splash of water it really isn’t designed to survive a heavy rain shower. The Camrade covers are not expensive and much better than wrapping the camera in a bin bag. When not in use the cover slips into a nice soft pouch that you can keep in your camera bag until the next time you need it.
One of the cameras I used a lot in Norway is the new Sony FDR-X3000 action cam. What’s different about this POV camera is that the lens and sensor are actually mounted in an internal miniaturised gimbal. This really does work and helps stabilise the image.
There is also a tiny bluetooth monitor that you can wear on your wrist to view the pictures and control the camera. The image quality you get from these tiny cameras really is quite amazing. Take a look at the video to find out more and see some sample footage.
Camera setup, reviews, tutorials and information for pro camcorder users from Alister Chapman.