# How Big a Light do I Need?

Experience goes a long way, but sometimes you need to be more precise about what size of lighting instruments are required for a particular scene. Night exteriors, for example; you don’t want to find out on the day that the HMI you hired as your “moon” backlight isn’t powerful enough to cover the whole of the car park you’re shooting in. How can you prep correctly so that you don’t get egg on your face?

There are two steps: 1. determine the intensity of light you require on the subject, and 2. find a combination of light fixture and fixture-to-subject distance that will provide that intensity.

### The Required intensity

The goal here is to arrive at a number of foot-candles (fc). Foot-candles are a unit of light intensity, sometimes more formally called illuminance, and one foot-candle is the illuminance produced by a standard candle one foot away. (Illuminance can also be measured in the SI unit of lux, where 1 fc ≈ 10 lux, but in cinematography foot-candles are more commonly used. It’s important to remember that illuminance is a measure of the light incident to a surface, i.e. the amount of light reaching the subject. It is not to be confused with luminance, which is the amount of light reflected from a surface, or with luminous power, a.k.a. luminous flux, which is the total amount of light emitted from a source.)

Usually you start with a T-stop (or f-stop) that you want to shoot at, based on the depth of field you’d like. You also need to know the ISO and shutter interval (usually 1/48th or 1/50th of a second) you’ll be shooting at. Next you need to convert these facets of exposure into an illuminance value, and there are a few different ways of doing this.

One method is to use a light meter, if you have one, which you enter the ISO and shutter values into. Then you wave it around your office, living room or wherever, pressing the trigger until you happen upon a reading which matches your target f-stop. Then you simply switch your meter into foot-candles mode and read off the number. This method can be a bit of a pain in the neck, especially if – like mine – your meter requires fiddly flipping of dip-switches and additional calculations to get a foot-candles reading out of.

A much simpler method is to consult an exposure table, like the one below, or an exposure calculator, which I’m sure is a thing which must exist, but I’ll be damned if I could find one.

Some cinematographers memorise the fact that 100fc is f/2.8 at ISO 100, and work out other values from that. For example, ISO 400 is four times (two stops) faster than ISO 100, so a quarter of the light is required, i.e. 25fc.

Alternatively, you can use the underlying maths of the above methods. This is unlikely to be necessary in the real world, but for the purposes of this blog it’s instructive to go through the process. The equation is:

where

• b is the illuminance in fc,
• f is the f– or T-stop,
• s is the shutter interval in seconds, and
• i is the ISO.

Say I’m shooting on an Alexa with a Cooke S4 Mini lens. If I have the lens wide open at T2.8, the camera at its native ISO of 800 and the shutter interval at the UK standard of 1/50th (0.02) of a second…

… so I need about 12fc of light.

### The right instrument

In the rare event that you’re actually lighting your set with candles – as covered in my Barry Lyndon and Stasis posts – then an illuminance value in fc is all you need. In every other situation, though, you need to figure out which electric light fixtures are going to give you the illuminance you need.

Manufacturers of professional lighting instruments make this quite easy for you, as they all provide data on the illuminance supplied by their products at various differences. For example, if I visit Mole Richardson’s webpage for their 1K Baby-Baby fresnel, I can click on the Performance Data table to see that this fixture will give me the 12fc (in fact slightly more, 15fc) that I required in my Alexa/Cooke example at a distance of 30ft on full flood.

Other manufacturers provide interactive calculators: on ETC’s site you can drag a virtual Source Four back and forth and watch the illuminance read-out change, while Arri offers a free iOS/Android app with similar functionality.

If you need to calculate an illuminance value for a distance not specified by the manufacturer, you can derive it from distances they do specify, by using the Inverse Square Law. However, as I found in my investigatory post about the law, that could be a whole can of worms.

If illuminance data is not available for your light source, then I’m afraid more maths is involved. For example, the room I’m currently in is lit by a bulb that came in a box marked “1,650 lumens”, which is the luminous power. One lumen is one foot-candle per square foot. To find out the illuminance, i.e. how many square feet those lumens are spread over, we imagine those square feet as the area of a sphere with the lamp at the centre, and where the radius r is the distance from the lamp to the subject. So:

where

• is again the illuminance in fc,
• is the luminous power of the souce in lumens, and
• r is the lamp-to-subject distance in feet.

(I apologise for the mix of Imperial and SI units, but this is the reality in the semi-Americanised world of British film production! Also, please note that this equation is for point sources, rather than beams of light like you get from most professional fixtures. See this article on LED Watcher if you really want to get into the detail of that.)

So if I want to shoot that 12fc scene on my Alexa and Cooke S4 Mini under my 1,650 lumen domestic bulb…

… my subject needs to be 3’4″ from the lamp. I whipped out my light meter to check this, and it gave me the target T2.8 at 3’1″ – pretty close!

### Do I have enough light?

If you’re on a tight budget, it may be less a case of, “What T-stop would I like to shoot at, and what fixture does that require?” and more a case of, “Is the fixture which I can afford bright enough?”

Let’s take a real example from Perplexed Music, a short film I lensed last year. We were shooting on an Alexa at ISO 1600, 1/50th sec shutter, and on Arri/Zeiss Ultra Primes, which have a maximum aperture of T1.9. The largest fixture we had was a 2.5K HMI, and I wanted to be sure that we would have enough light for a couple of night exteriors at a house location.

In reality I turned to an exposure table to find the necessary illuminance, but let’s do the maths using the first equation that we met in this post:

Loading up Arri’s photometrics app, I could see that 2.8fc wasn’t going to be a problem at all, with the 2.5K providing 5fc at the app’s maximum distance of 164ft.

That’s enough for today. All that maths may seem bewildering, but most of it is eliminated by apps and other online calculators in most scenarios, and it’s definitely worth going to the trouble of checking you have enough light before you’re on set with everyone ready to roll!

SaveSave

SaveSave

# Colour Rendering Index

Many light sources we come across today have a CRI rating. Most of us realise that the higher the number, the better the quality of light, but is it really that simple? What exactly is Colour Rendering Index, how is it measured and can we trust it as cinematographers? Let’s find out.

### What is C.R.I.?

CRI was created in 1965 by the CIE – Commission Internationale de l’Eclairage – the same body responsible for the colour-space diagram we met in my post about How Colour Works. The CIE wanted to define a standard method of measuring and rating the colour-rendering properties of light sources, particularly those which don’t emit a full spectrum of light, like fluorescent tubes which were becoming popular in the sixties. The aim was to meet the needs of architects deciding what kind of lighting to install in factories, supermarkets and the like, with little or no thought given to cinematography.

As we saw in How Colour Works, colour is caused by the absorption of certain wavelengths of light by a surface, and the reflection of others. For this to work properly, the light shining on the surface in the first place needs to consist of all the visible wavelengths. The graphs below shows that daylight indeed consists of a full spectrum, as does incandescent lighting (e.g. tungsten), although its skew to the red end means that white-balancing is necessary to restore the correct proportions of colours to a photographed image. (See my article on Understanding Colour Temperature.)

Fluorescent and LED sources, however, have huge peaks and troughs in their spectral output, with some wavelengths missing completely. If the wavelengths aren’t there to begin with, they can’t reflect off the subject, so the colour of the subject will look wrong.

Analysing the spectrum of a light source to produce graphs like this required expensive equipment, so the CIE devised a simpler method of determining CRI, based on how the source reflected off a set of eight colour patches. These patches were murky pastel shades taken from the Munsell colour wheel (see my Colour Schemes post for more on colour wheels). In 2004, six more-saturated patches were added.

The maths which is used to arrive at a CRI value goes right over my head, but the testing process boils down to this:

1. Illuminate a patch with daylight (if the source being tested has a correlated colour temperature of 5,000K or above) or incandescent light (if below 5,000K).
2. Compare the colour of the patch to a colour-space CIE diagram and note the coordinates of the corresponding colour on the diagram.
3. Now illuminate the patch with the source being tested.
4. Compare the new colour of the patch to the CIE diagram and note the coordinates of the corresponding colour.
5. Calculate the distance between the two coordinates, i.e. the difference in colour under the two light sources.
6. Repeat with the remaining patches and calculate the average difference.

Here are a few CRI ratings gleaned from around the web:

 Source CRI Sodium streetlight -44 Standard fluorescent 50-75 Standard LED 83 LitePanels 1×1 LED 90 Arri HMI 90+ Kino Flo 95 Tungsten 100 (maximum)

### Problems with C.R.I.

There have been many criticisms of the CRI system. One is that the use of mean averaging results in a lamp with mediocre performance across all the patches scoring the same CRI as a lamp that does terrible rendering of one colour but good rendering of all the others.

Further criticisms relate to the colour patches themselves. The eight standard patches are low in saturation, making them easier to render accurately than bright colours. An unscrupulous manufacturer could design their lamp to render the test colours well without worrying about the rest of the spectrum.

In practice this all means that CRI ratings sometimes don’t correspond to the evidence of your own eyes. For example, I’d wager that an HMI with a quoted CRI in the low nineties is going to render more natural skin-tones than an LED panel with the same rating.

I prefer to assess the quality of a light source by eye rather than relying on any quoted CRI value. Holding my hand up in front of an LED fixture, I can quickly tell whether the skin tones looks right or not. Unfortunately even this system is flawed.

The fundamental issue is the trichromatic nature of our eyes and of cameras: both work out what colour things are based on sensory input of only red, green and blue. As an analogy, imagine a wall with a number of cracks in it. Imagine that you can only inspect it through an opaque barrier with three slits in it. Through those three slits, the wall may look completely unblemished. The cracks are there, but since they’re not aligned with the slits, you’re not aware of them. And the “slits” of the human eye are not in the same place as the slits of a camera’s sensor, i.e. the respective sensitivities of our long, medium and short cones do not quite match the red, green and blue dyes in the Bayer filters of cameras. Under continuous-spectrum lighting (“smooth wall”) this doesn’t matter, but with non-continuous-spectrum sources (“cracked wall”) it can lead to something looking right to the eye but not on camera, or vice-versa.

### Conclusion

Given its age and its intended use, it’s not surprising that CRI is a pretty poor indicator of light quality for a modern DP or gaffer. Various alternative systems exist, including GAI (Gamut Area Index) and TLCI (Television Lighting Consistency Index), the latter similar to CRI but introducing a camera into the process rather than relying solely on human observation. The Academy of Motion Picture Arts and Sciences recently invented a system, Spectral Similarity Index (SSI), which involves measuring the source itself with a spectrometer, rather than reflected light. At the time of writing, however, we are still stuck with CRI as the dominant quantitative measure.

So what is the solution? Test, test, test. Take your chosen camera and lens system and shoot some footage with the fixtures in question. For the moment at least, that is the only way to really know what kind of light you’re getting.

SaveSave

SaveSaveSaveSave

SaveSave

SaveSave

SaveSave

SaveSave

SaveSave

SaveSave

SaveSave

SaveSave

# “The Knowledge”: Lighting a Multi-camera Game Show

Last week I discussed the technical and creative decisions that went into the camerawork of The Knowledge, a fake game show for an art installation conceived by Ian Wolter and directed by Jonnie Howard. This week I’ll break down the choices and challenges involved in lighting the film.

The eighties quiz shows which I looked at during prep were all lit with the dullest, flattest light imaginable. It was only when I moved forward to the nineties shows which Jonnie and I grew up on, like Blockbusters and The Generation Game, that I started to see some creativity in the lighting design: strip-lights and glowing panels in the sets, spotlights and gobos on the backgrounds, and moodier lighting states for quick-fire rounds.

Jonnie and I both wanted The Knowledge‘s lighting to be closer to this nineties look. He was keen to give each team a glowing taxi sign on their desks, which would be the only source of illumination on the contestants at certain moments. Designer Amanda Stekly and I came up with plans for additional practicals – ultimately LED string-lights – that would follow the map-like lines in the set’s back walls.

Once the set design had been finalised, I did my own dodgy pencil sketch and Photoshopped it to create two different lighting previsualisations for Jonnie.

He felt that these were a little too sophisticated, so after some discussion I produced a revised previz…

…and a secondary version showing a lighting state with one team in shadow.

These were approved, so now it was a case of turning those images into reality.

We were shooting on a soundstage, but for budget reasons we opted not to use the lighting grid. I must admit that this worried me for a little while. The key-light needed to come from the front, contrary to normal principles of good cinematography, but very much in keeping with how TV game shows are lit. I was concerned that the light stands and the cameras would get in each others’ way, but my gaffer Ben Millar assured me it could be done, and of course he was right.

Ben ordered several five-section Strato Safe stands (or Fuck-offs as they’re charmingly known). These were so high that, even when placed far enough back to leave room for the cameras, we could get the 45° key angle which we needed in order to avoid seeing the contestants’ shadows on the back walls. (A steep key like this is sometimes known as a butterfly key, for the shape of the shadow which the subject’s nose casts on their upper lip.)  Using the barn doors, and double nets on friction arms in front of the lamp-heads, Ben feathered the key-light to hit as little as possible of the back walls and the fronts of the desks. As well as giving the light some shape, this prevented the practical LEDs from getting washed out.

Once those key-lights were established (a 5K fresnel for each team), we set a 2K backlight for each team as well. These were immediately behind the set, their stands wrapped in duvetyne, and the necks well and truly broken to give a very toppy backlight. A third 2K was placed between the staggered central panels of the set, spilling a streak of light out through the gap from which host Robert Jezek would emerge.

A trio of Source Fours with 15-30mm zoom lenses were used for targeted illumination of certain areas. One was aimed at The Knowledge sign, its cutters adjusted to form a rectangle of light around it. Another was focused on the oval map on the floor, which would come into play during the latter part of the show. The last Source Four was used as a follow-spot on Robert. We had to dim it considerably to keep the exposure in range, which conveniently made him look like he had a fake tan! Ben hooked everything, in fact, up to a dimmer board, so that various lighting cues could be accomplished in camera.

The bulk of the film was recorded in a single day, following a day’s set assembly and a day of pre-rigging. A skeleton crew returned the next day to shoot pick-ups and promos, a couple of which you can see on Vimeo here.

I’ll leave you with some frame grabs from the finished film. Find out more about Ian Wolter’s work at ianwolter.com.

SaveSave

SaveSave

SaveSave

# “Above the Clouds”: February 2017 Pick-ups

Last weekend saw many of the crew of Above the Clouds reunite to shoot the remaining scenes of this comedy road movie. Principal photography was captured on an Alexa Mini during summer 2016 on location in Kent, on the Isle of Skye, and at Longcross Studio in Buckinghamshire, with additional location shooting on a Blackmagic Micro Cinema Camera in October.

The outstanding scenes were to be photographed on stage, at Halliford Studio in Shepperton, this time on an Arri Amira. The Amira uses the same sensor as the Alexas, allowing us to match the look from principal photography in the most cost-effective way. With the addition of a Premium license, the camera is capable of the same ProRes 4444 recording codec as the Alexas too. As per last summer, our glass was a set of Arri/Zeiss Ultra Primes, with a half Soft FX filter to take the digital edge off.

Director Leon Chambers designed and built the set himself, sending me photos of a scale model well in advance. He was also specific about certain lighting cues and states that were required across the two sets and six scenes we would be recording to complete the movie. Based on this information, I concocted a lighting plan, which I communicated to Halliford’s in-house gaffer Micky Reeves by Photoshopping stock images of lamps onto Leon’s set model photos.

Last Saturday was devoted to pre-lighting the sets, mainly the kitchen, while construction work continued on the second set.

### Day 24 / Sunday

We begin with a morning scene. A 5K fresnel serves as a low sun, streaking across the back wall of the set (see my post about lighting through windows). Even with this direct light four stops over, the natural bounce off the set isn’t enough to bring actor Philip Jackson – with his back to the window – up to key. Micky rigs a Dedo firing into a soft silver bounce just out of frame to solve the problem.

Also coming through the window are two 4×4 kinos, rigged on goalposts above the window. Their daylight tubes reflect off the blinds, serendipitously creating the illusion of a blue sky “outdoors”, where in fact there is only a wall and a white backdrop.

Philip exits into the hallway and disappears from view, supposedly to go out through the front door. No door exists. Instead there is a flag which spark Amir Moulfi rotates in front of a 2K, creating a momentary oblong of light in which Philip’s shadow appears.

The next scene follows on from an exterior captured last October at dusk, when the natural light was soft, flat and cool in colour, cheated even cooler with the white balance. This failing daylight is to be the only source of illumination now in the kitchen set, until Philip enters and turns on the lights. This is the main reason that the daylight 4×4 kinos outside the window were rigged. A third kino from the direction of the front door is added, plus a small LED reporter light to pick an important prop out of the shadows.

Lead actress Naomi Morris enters, silhouetted against the windows. Then Philip enters and hits the lights. Simultaneously, Amir flips a breaker on a lunchbox, activating a hanging practical fixture above the breakfast bar and the 5K which that practical motivates.

Generally I don’t like toplight. It throws the eyes – those windows to the soul… or windows to the performance – into shadow. But with the hanging practical in shot, whatever I was going to use to beef it up had to be somewhat toppy or it wouldn’t make sense. I considered space-lights and Jem balls, but in consultation with Micky I ultimately picked a 5K with a chimera, coming in at a 45 degree back/toplight angle. As you can see from the photos, this looks almost comically large. But large and close means soft, which is what I want. It had to be soft enough to wrap both actors when they faced each other across the bar.

But why such a large lamp? Why not use a 2K, like Micky suggested yesterday? Bitter experience has always taught me to go with a bigger unit than you think you need, particularly if you’re softening it, and particularly if it’s going to take a while to rig. (The 5K was hung from another goalposts set-up.) We ended up dimming the 5K to 50% and scrimming it down a stop and a half. But having too much light like that is easy to deal with. If we had put up a 2K and it wasn’t bright enough, we would have to have taken the whole thing down and re-rigged with a 5K. And even if the 2K had seemed sufficient to begin with, blocking can often take actors into unexpected, dark corners of the set. Being able to turn up a dimmer a couple of notches to handle that kind of situation is very useful.

Besides the 5K, there are a few other sources playing: some 300W hairlights, a pup bouncing off the side of a cupboard to bring up the area around the cooker, a China ball in the hallway, and Leon’s Rosco LitePads serving as practical under-cabinet down-lighters.

### Day 25 / Monday

I probably shouldn’t say what today’s set is, because it’s a little bit of a spoiler. There are some lighting similarities to the kitchen: again we have a character flicking a light switch, bringing on two hanging overhead practicals and a 2K with a chimera to beef them up.

A practical lamp on a desk was supposed to be turned on during the scene as well, but we all forget until it’s too late. It would have bounced off the desk and given Philip a little eye-light, and at first I regret losing this. But soon I realise that it is more appropriate for the scene not to have that level of refinement, for the lighting to be a little raw. The toppy, “broken key” angle of the chimera’s light works well for this tone too.

We wrap just before noon, releasing Naomi to high-tail it to Oxford to appear on stage in a musical this evening. Eventually there will be second-unit-style GVs and establishing shots to do, but there will only be three or four of us for that. For the cast and most of the crew, today brings Above the Clouds to an end, eight months after the camera first rolled.

See all my Above the Clouds posts here, or visit the official website.

# 5 Tips for Working with Practicals

As the sensitivity and dynamic range of cameras has increased, practicals have become a more and more important and popular tool in the cinematographer’s arsenal. A practical is any light source that appears in the frame. It could be a fluorescent strip-light, a table lamp, car headlights, candles, a fireplace, an iPad, fairy lights, street lamps, a torch, a security light… any light that could be realistically found in the place where your scene is set.

Here are five pieces of advice I’ve put together from my own experiences working with practical lights.

1. Liaise continually with the director and art department.

Although the bulb, wiring and power supply are the responsibility of the lighting department, the fixture itself falls under the purview of the art department. A good production designer will be thinking of light sources from the very beginning of their set design process. This is the start of a conversation which will continue throughout preproduction, as you the DP ask for fixtures in certain positions to make the set and actors look good, and the designer either says yes or asks for compromises so as not to ruin the aesthetics or believability (or budget!) of their design. The places a DP wants light sources in order to get the best modelling of the talent are often not the places a real human being would choose to install a light source in their home/office/dungeon etc. Some designers will demand realism and fight you on these decisions; others are open to artistic license. Either way, you must respect the symbiotic relationship between your two departments and do your best to reach a solution that works for both of you.

Keeping the director in the loop is also very important. When it comes to lighting, practicals are one of the things most likely to cause disagreement between the director and DP. You may have spent an hour lighting the set to be motivated by the candles all around, only for the director to walk onto set and say that they feel it makes no sense within the story for someone to have lit the candles in this scene. At which point, if you can’t change the director’s mind, you will find yourself hastily relighting the set while the 1st AD shakes their head in despair.

2. Sometimes it’s as simple as turning it on.

Earlier in my career, whenever I saw a practical, I felt that I had to set up a movie light somewhere out of frame in order to beef up the amount of light apparently coming from that practical. And traditionally, this is indeed the way DPs have worked, because film stocks weren’t sensitive enough to get an acceptable exposure from typical practicals like table lamps. Or it was impossible to find a level for the practical where it was bright enough to expose the talent but dim enough that the lamp itself didn’t read on camera as an ugly, over-exposed white blob.

But today’s digital cameras have a wider dynamic range, making it much easier to expose both the source and the subject acceptably. So ask yourself, do you really need that movie light? Roger Deakins, the world’s most celebrated living cinematographer, says he commonly lights his sets now with predominantly practical sources. Take a look at your scene without any additional lights, and only add extra sources if your practical’s illumination isn’t reaching the distance it needs to.

And practicals don’t even need to light the talent. Sometimes you have a scene perfectly well illuminated with other sources, but turning on a practical in the background just adds the icing on the cake. It may not illuminate anything but a small pool immediately around itself, but that little pool of orange light might add colour contrast, production value and interest. I’ve often seen daylight interior scenes on TV or in movies where bright shafts of “sunlight” are blasting in through a window, and no-one would realistically need to turn an artificial light on, but nonetheless several table lamps are glowing away in the background – because it looks great!

3. Always use dimmers.

As I’ve already said, finding that perfect brightness for your practical can be a delicate balancing act, so always have your crew put practicals on dimmers (a.k.a. “squeezers”) to make it easy to find that right level. Besides, practicals often look best with a warmer colour temperature, and you can get that by dimming them down, if they’re tungsten, adding to the cosy feel.

4. Keep other sources off the practical.

One of the reasons practicals look good is because they create contrast in the frame: a bright patch spreading out into darkness. If other light is falling on the practical, this effect will be washed out and reduced. If the other source is bright, it may even make the practical look like it’s not switched on. (Just like if you take a torch outside in daylight and turn it on, it doesn’t look like it’s on at all because the sun is so overpowering.)

If possible, other sources should be flagged so that they don’t hit the practical. This is something that an experienced gaffer will often have done as a matter of course.

5. Dim the camera side of the practical.

Even with the wide dynamic range of today’s cameras, the flame or bulb of a practical may still look unpleasantly bright on camera. To deal with this, depending on the design of the fixture, you may be able to hide a small piece of ND gel inside it on the camera side. If properly arranged, this will cut the light travelling directly into the camera lens, but not the light shining in other directions and illuminating the talent.

Alternatively, the glass case of a lantern can be sprayed black on the camera side. The paint will not be picked up by the camera because there will still be a lot of light coming through it, but it should cut enough brightness to eliminate lens flare and reduce highlight clipping.

I hope these tips are helpful next time you shoot with practicals. Happy lighting, and merry Christmas!

# Lighting Micro-sets

From time to time I help out my friend Kate Madison shooting show reels for actors. The fun and the challenge is in creating and lighting little micro-sets to capture angles that look like they might be lifted out of a scene from a much larger production, all with limited equipment.

Here’s an interesting shot from a recent showreel for Dana Hajaj. This was intended to resemble a Good Wife style legal drama, though actually the first reference that the lawyer’s office setting brought to my mind was Ally McBeal. I remember how they often had hot sunlight coming in through their office windows which would hit the talent from the chest down, while softer, indirect daylight would illuminate the faces.

Clearly this technique wasn’t exactly going to work for an MCU, but it did get me thinking about windows as two-in-one sources: a hard source which adds interest and ‘sheen’ to the image but is too harsh to hit faces with, and a soft sources for faces. Often cinematographers will use two different lights through the same window to achieve these two distinct effects. (I sometimes employ what I call a “Window Wrap” to this end.)

Now, the set for this showreel shot was just a red wall and sconce. (We tried a plant in the corner but couldn’t get it to work.) I wanted to suggest what the rest of the set might be, beyond the borders of this MCU, and simulating a window seemed like a natural choice. Furthermore, a window with Venetian blinds would help sell what was really a living room as a place of business. But this was not film noir; I didn’t want stripes of light on Dana’s face. Instead I used them to add interest to the wall.

Kate had a slatted-top stool in the hall which threw convincing “blinds” shadows when clamped to a C-stand in front of an 800W Arrilite. Ideally the shadows would have been sharper, but without a Dedo or a par this was the best I could do.

To get the maximum richness from the practical, I put a topper (black wrap clipped to the stool!) on the 800 to keep it off the sconce, and placed CTO inside the lampshade to warm up the fluorescent bulb.

To key Dana, I fired a 1K Arrilite into a 4’x4′ polyboard which was positioned next to the stool. Tungsten bounced off poly gives a beautiful soft, matt quality of light, and is a great way to key talent.

The backlight comes from a 1’x1′ LED panel set to about 4500K. What is the motivation for this source? North light coming from another window maybe? The great thing about micro-sets is there’s no wide shot so I don’t have to worry about that if I don’t want to! The motivation is that cold backlight looks good on black hair, and that’s that.

As we prepared to roll, I wondered if I should increase the contrast more. I could have done this by (a) flagging the poly bounce to prevent it filling in the “blinds” shadows on the wall and (b) bringing in negative fill on the talent’s camera right side to kill the ambience. But I decided that more contrast was not appropriate for this kind of piece.

For another scene for Dana’s reel, we mocked up a remote Arabian campsite on Kate’s patio! Kate used a piece of fabric hung from a post and two light stands to representing the tent.

I wanted to give the impression that if we cut to a wide shot – which of course we never do, but if we did – that it would show a vast landscape, perhaps a desert, all backlit by moonlight. On this hypothetical production, I would generate that moonlight with 18Ks on condor cranes, gelled with Steel Blue.

But on this tight shot I was able to achieve the same effect with two far smaller sources, both gelled with Steel Blue. (This is a blue with more green in it than CTB. It’s prettier and has connotations of many 80s and 90s thrillers and action movies that seemed to use copious amounts of this gel.) In the deep background is an LED panel, 3/4 backlighting a couple of blurry apple trees that could maybe play as vegetation around an oasis. Immediately behind the “tent” is a 40″ C-stand, top floor, with a 1K Arrilite on it. So close to the talent, the 1K comes down at a steep enough angle to imply moonlight, or an 18K on a condor, depending on how you want to look at it.

The flames from the fire pit weren’t doing much to light Dana, so I bounced another 1K off a gold reflector on the floor next to the fire. During takes I wiggled the reflector to add dynamics to the light.

To add a final touch of production value, I suggested a foreground practical. Kate found a candle lantern which we hung from a flag arm just in front of camera. Every frame of a Blockbuster movie is packed with details, so things like this help a lot to sell the scale.

For more on shooting micro-sets, check out my blog from Above the Clouds, a feature that had several of them. Visit actorsatworkproductions.co.uk for showreel info.

In this final part of the Know Your Lights series, I’m taking a look at some of the LED fixtures currently available.

LEDs (light emitting diodes) generate light through electroluminescence. When a controlled direct current is applied to the electrodes, electrons in the semi-conductor reconfigure, releasing energy as light. LEDs have been around since the early sixties, but for decades they were only capable of emitting a weak red glow, restricting their applications to things like TV standby lights and digital clocks. In recent years the brightness and colour range of LEDs has improved dramatically, making them practical alternatives to traditional light sources.

Compared with those sources – tungsten, HMI and fluorescent –  LEDs are more efficient, lighter, generate less heat, have a longer life, and are less likely to break and less dangerous when they do. They are fully dimmable, without the colour temperature changing, but if you wish, some fixtures allow you to alter the colour temperature with the turn of a knob.

On the down side, LED units are expensive, lack the raw power of large HMI or tungsten fixtures, and can often suffer from poor CRI (colour rendering index – see the overview for more info).

The technology is improving rapidly, and LEDs will only get better over the coming years. For now, many regard them as speciality lights, and they are almost always outnumbered by tungsten, HMI and fluorescent units in a drama lighting package. But some productions have really embraced them, an example being Guardians of the Galaxy, where many of the colourful practicals built into the sets were LEDs. Because they can be squeezed into smaller spaces than any other kind of light, and because you can get around the poor CRI by using coloured lamps, or gelling white ones, LEDs are well suited to creating practical glows from computers, control desks and other technology.

These are just a few of the LED fixtures currently on the market…

Panels

1’x1′ LitePanels are perhaps the most common LED unit. These panels have two dials on the back: one for brightness, and one for colour temperature (3200-5600K). They can be run off mains or a V-lock battery, drawing 40W to output about as much light as a 200W HMI.

I usually ask for a couple of these panels in my package, and they are great for situations like these:

• As you are about to roll, you spot an area of the frame that needs a little extra splash of light. It is the work of moments to slap a battery on a LitePanel and fly it into shot.
• A light needs to be situated in a tight space in the set, or in a spot which a power cable couldn’t reach without appearing in frame, or both. The fact that you can just prop these panels up against the set without worrying about them getting hot and damaging something is huge.
• When required to shoot a night exterior without a generator, LED panels can really help you out. Even if you do have a genny, the ability to set up a source without running power to it is extremely useful. A short film I shot called Forever Alone is a good example.
• Wrapped in a diffuser like tough-spun or muslin, they make good fill lights or eye lights for day exterior close-ups.
• They can make good TV sources, particularly if your set-up time is limited. A spark can twiddle the brightness and colour temp dials during takes to simulate changing images on the TV screen.

There are many manufacturers producing panels in 1’x1′ and other sizes, but LitePanels are the best ones I’ve encountered. However, I’ve yet to come across any LED unit with a good enough CRI to use as a key light.

A range I haven’t used is the Arri SkyPanels. Designed primarily to be rigged overhead from studio grids, they come in 30, 60 and 120cm lengths. The coolest thing about these units is that you don’t need to gel them; just punch in the Lee or Rosco code of the gel you want to use, and the light instantly changes colour!

Rosco Lite Pads go for a slightly different approach. The LEDs are arranged around the edges of these panels, and bounce off the white backing to produce a soft daylight source. They’re not very bright, and again the CRI is not great, but the range of shapes and sizes they come in mean that you can find one to fit most tricky spaces.

I used these a lot on Above the Clouds (check out the blog posts) in many different situations. Two 3″x12″ Lite Pads saw extensive use as fill/eye light, taped to the dashboard of a Fiat 500 in driving scenes. The other standard sizes are  3″x6″, 6″x6″, 6″x12″, 12″x12″ and 3″ circular. The panels themselves are stripped down, so batteries and dimmers can be sited remotely.

Rosco also makes LitePad Vectors, which are more like other brands of LED panel, with on-board dimmers and increased light output, and they can even make custom LitePads.

Fresnels

Several companies make small fresnels which at first glance appear to be HMIs, but are in fact LEDs. LitePanels make the Sola 6C and Sola ENG, equivalent to 200 and 100W HMIs respectively. Arri makes the L5, L7 and L10 units, which are each available in three models with differing brightness and colour-tuneability characteristics. The brightest L10 models are comparable with a 2K tungsten fresnel, while drawing a fifth of the power.

There are budget models out there too, such as the NiceFoto CE-1500Ws, which I used a little on Ren: The Girl with the Mark. As with all budget LED and fluorescent lights, the CRI is very poor, but it was useful when we lacked enough traditional fixtures.

Overall, LED fresnels are currently most relevant in scenarios where power is very limited, or portability and lack of heat is particularly important – in a nutshell, electronic news-gathering (ENG).

Ribbons

One of the most exciting things about LEDs is that because the individual diodes are so small, they don’t necessarily have to be housed in a fixture of any kind. LiteGear, for example, supplies LiteRibbons, which are strips of LEDs “mounted to a white backing material that is flexible, cuttable and adhesive backed”. The possibilities for these ribbons are pretty much endless. Here are some examples:

• The Enterprise bridge set featured in the last three Star Trek movies has all its control panels lit by LiteRibbons.
• Mad Max: Fury Road, and many other movies with driving scenes, had strips of LEDs mounted to the ceiling, window frames and pillars of the truck cab to increase the exposure inside.
• The mini reactor that powers Iron Man’s suit is illuminated by LiteRibbon LEDs.

Conclusion

Some predict that, as LEDs get brighter, cheaper and higher in CRI, they will eventually replace every other kind of lighting. For now though, they’re just another part of the toolkit in which tungsten and HMIs, and to a lesser extent fluorescents, are the go-to tools.

There is a fifth type of lighting that is emerging too: plasma lighting, but it’s so new and so rare at the moment that I don’t feel equipped to write a post about it yet. But you can read about it over on Shane Hurlbut’s blog.

Another great blog to teach you about the many lights out there is Set Lighting, written by experienced Hollywood gaffer Martijn Veltman. His site was really useful when I was researching this series.

Of course, the most important thing is not what lights you have, but how you use them. There are many, many posts here on neiloseman.com to teach you about that. Check out the Lighting Techniques series for some basics, watch my Lensing Ren video series to see how all four types of lighting are used in practice on a real shoot, or simply search the tag ‘lighting’ for a wealth of material.

Happy lighting!

Tungsten and/or HMI lamps are usually the workhorse units of a lighting package, providing the power that is needed to key-light all but the smallest of set-ups. But they’re not right for every situation. If you don’t need the punch of a point source, and you want something a little softer, fluorescents might be the answer.

This is the third category of lighting units I’m covering in my Know Your Lights series; back up to the overview if you want to start from the beginning.

Fluorescent units use very similar technology to HMIs, with electrodes exciting a gas so that it gives off UV light. The phosphor coating on the tube absorbs the UV light and fluoresces, i.e. re-emits the light in the visible spectrum. Like HMIs, fluorescent units require a ballast to regulate the current.

One of the most notable early uses of fluorescents was in Robocop (1987). Jost Vocano, ASC chose the fixtures because the long, thin reflections looked great on Robocop’s suit. The flip side of that coin is that under certain circumstances fluorescents can make actors’ skin unpleasantly shiny. There was a scene in Ren: The Girl with the Mark where the poor make-up artist had to cake layers of powder onto Sophie Skelton to combat the shine of a Kino Flo I had set up.

One way I often use fluorescents is as a “Window Wrap”, a soft source that augments a hard HMI coming in through a window to wrap the light more pleasingly around the talent’s face. Or I’ll place a fluorescent outside the room, to represent or enhance indirect daylight spilling through a doorway.

Being soft sources, the light rays which fluorescents emit spread out widely, meaning the intensity drops off quickly as you move away from the lamp. (We refer to this as “throw”: fluorescents have little throw, whereas spotlights have a lot of throw.) For this reason they start to become pretty ineffective once you get more than about 6ft away from them, depending on the model.

Kino Flo is far and away the most common brand of fluorescent lighting used in the film and TV industry today, so apologies if the rest of this post reads a little like an advert for them. They’re not paying me, honestly!

The company was started by gaffer Frieder Hochheim and best boy Gary Swink after inventing the units for the 1987 comedy-drama Barfly (DP: Robby Müller, BVK). They required a fixture small enough to tuck into little alcoves in a bar location, without getting hot and causing damage.

Kino Flos come in two different kinds:

Remote Ballast

With these units, the lighting fixture is separate to the ballast, and they are connected by a header cable, just like HMIs. Remote units are usually referred to by two numbers, the first representing the length of the tubes in feet, and the second representing the number of tubes. So a unit with two tubes, four feet in length, is called a “4ft 2-bank”, often written as: 4’x2 (pronounced “four by two”).

The most common units are 2’x4 (a.k.a. “fat boy”), 4’x4 and 4’x2, but others are available, including “Single Flo” units and 6ft/8ft “Mega” units.

The ballasts allow you to turn individual tubes on and off as required, and also feature a switch marked either Hi/Lo or 4ft/2ft, which reduces the light output by adjusting the current waveform.

Built-in Ballast

As you might expected, these models combine the fixture and ballast into a single unit. They are designed primarily for interview/ENG applications where it is more convenient to have everything in one. On drama productions it is generally preferable to have a remote fixture, which will be lighter, and a header cable running to an easily accessible ballast.

One advantage of built-in models over their remote cousins is that they are smoothly dimmable down to 5%.

Built-in units are known by names rather than numbers: “Diva-Lite” (2’x4), “Tegra” (4’x4) and “BarFly”, which resembles a swollen 1’x1′ LED panel. There is also the large “Image 87”, a 4’x8 fixture with a built-in ballast. It’s great for lighting green and blue screens because it puts out so much soft light.

Kino Flo tubes are available in five colours:

• KF55 – 5500K – i.e. daylight – identified by blue end caps on the tubes
• KF32 – 3200K – standard tungsten – gold end caps
• KF29 – 2900K – warm tungsten – red end caps
• 420nm blue – an extra-saturated blue for lighting blue screens
• 525nm green – for lighting green screens

Kino Flos often come with plastic grids known as “egg crates” or “louvres”. Their purpose is to make the light more directional, effectively polarising it on a macro scale. They come in black, silver and “honeycomb” varieties, the latter available in 45º, 60º and 90º angles so you can choose how directional the light becomes – and, as a side effect, how much intensity you lose.

It is possible to remove the tubes and wiring from a Kino Flo housing so that the lamps can be squeezed into a tight space. For example, on The Little Mermaid we needed to see a soft blue glow emanating from a small translucent compartment in an organ. Best boy “Captain” Dan Xeller removed a 2ft Kino tube from its housing and placed it inside the compartment, running the wires out the back to the ballast.

Other than Kino Flo, another brand of fluorescent lights you may come across is Pampa Lights. They come in rugged boxes which can be interlinked to create larger banks of illumination. Unfortunately, in my experience the CRI (see overview) is not good, and they are best avoided.

The same goes even more so for the many fluorescent softbox kits available on Ebay from Hong Kong sellers. Not only are they flimsy in construction and questionable in terms of electrical safety, but the CRI of the lamps is very, very poor. If you need a cheap soft source, you would be much better off bouncing a halogen work light off a white card.

Indeed, firing an incandescent source into a bounce board will give you a better quality of light than even a Kino Flo. But a fluorescent fixture won’t make the room unbearably warm, it can emit daylight-balanced light, and it’s quicker to set up than a bounce board and the attendant flags. In a nutshell, it’s more convenient.

Next week, the Know Your Lights series concludes with a look at the fast-evolving world of LED illumination.

Following on from last week’s look at tungsten units, today we focus on HMI lighting. HMIs are more complex technology than tungsten, meaning they are far more expensive, and more prone to problems, particularly if you get a deal from a hire company and they give you older units. But they are bright and relatively efficient and because of this, and their colour temperature of 5,600K, they are by far the most popular type of light used in today’s film and TV industry when battling or mixing with natural daylight.

HMIs (hydragyrum medium-arc iodide) operate by creating an arc between two electrodes. This arc excites a gas which produces the light. In order to ignite the arc, a ballast is required. This device also regulates the current, while a special header cable connects the ballast to the light.

Ballasts come in two types: electronic and magnetic. Magnetic ballasts are cheaper, but if you are shooting at a shutter interval out of sync with the cycling of your power supply – e.g. 1/48th of a second with a 50Hz UK power supply – the HMI will appear to flicker on camera. Electronic ballasts have a ‘flicker free mode’ which converts the sine wave of the power supply into a square wave so that the arc does not extinguish at any point in the cycle. A side effect of this is that the head and/or ballast can produce humming, buzzing or squealing noises. Therefore many electronic ballasts have a ‘silent mode’ which reduces the noise but only prevents flicker at standard frame rates, not for high-speed work. In practice, flicker is rarely a problem as the shutter angles of today’s digital cameras can easily be tweaked to deal with it at common frame rates.

Like tungsten units, HMIs are available in open face, par and fresnel varieties, though the open face models are not very common. Arri, the major manufacturers of HMIs, call their daylight par fixtures ‘Arrisun’. Other HMI brands include Film Gear, Silver Bullet and K5600, which makes Jokers (see below).

Measured by their wattage, standard HMIs sizes are: 200W, 575W, 1.2K, 2.5K, 4K, 6K, 12K, 18K.

The smaller models, up to 2.5K, are fairly common on no-budget sets, because they can run off a domestic power supply and so don’t require a generator. At the other end of the scale, 18Ks are standard for daylight exterior and interior work on medium budgets and above.

Because of their power, HMIs often play a key part in night exterior lighting too. A 12K or 18K on a condor crane may be used to simulate the moon, while other HMI units, perhaps bounced or coming through a frame, might serve as sidelight or fill. By choosing to shoot at 3,200K, you automatically turn these HMI sources blue, often a desirable look for nighttime work.

There are many variants on the standard HMIs. Here are some of the more common ones.

Pocket pars are little 125W daylight pars that can be run off batteries. Before the days of LED panels, I used one of these for eye-light on a short film set in a forest in daylight. They can also make a good TV gag when bounced off a wobbling silver reflector.

Jokers are small units that come in 400W and 800W models. They can be reconfigured in various ways and even slotted into Source 4 housings (see last week’s tungsten post) to convert these units to daylight. We used a 400W joker a couple of times on Heretiks, when there was little space to rig in but we needed a fair bit of punch – like daylight through a small window.

The Arrimax range uses a hybrid of par and fresnel technology. They are lighter and more efficient than standard HMIs – the 800W model puts out almost as much light as an ordinary 1.2K, for example – but they’re more expensive to hire and don’t create the nice shafts of light that some DPs like (ahem). The model numbers are the wattage in tenths of a kilowatt: M8 (800W), M18 (1.8K), M40 (4K), M90 (9K) and the anomalously-named Arrimax 18/12 which accepts both 12K and 18K bubbles.

Helium Balloons are designed to provide a soft overhead illumination for night exteriors or high-ceilinged interiors. They come in a range of shapes and sizes, and aren’t necessarily HMIs; they can be fitted with tungsten lamps, or a combination of both.

Following on from my ‘Know Your Lights’ overview last week, today I’ll look in more detail at the first category of lamps and the various units available and when you might use them.

And that first category is incandescent lighting, commonly known as tungsten. It is the oldest, simplest and most robust lighting technology. Tungsten lamps are the cheapest to hire, the easiest to repair, and emit a smoother spectrum of light than any other artificial sources, making for the most natural skin tones. For my money, there’s no better way to artificially light a human face than by bouncing a tungsten source off polyboard.

Tungsten lighting units can be sub-categorised by the style of reflectors and/or lenses in the heads…

Open-face

 Ianiro Lilliput, a 300W open-face light Generic 800W open-face light Arrilite 1000, a 1K open-face light Generic 2K open-face light

The simplest instruments are known as ‘open-face’ because they have no lens to focus the light. By far the most common units are the 800 Watt and 2,000 Watt models. These are often referred to as ‘redheads’ and ‘blondes’ respectively, though I strongly discourage these terms for reasons touched on here. 300W models – dubbed ‘Lilliputs’ by manufacturer Ianiro – are also available, as well as 1Ks and much larger models like the Mole-Richardson Skypan 5K and Skylite 10K.

While I have lit entire no-budget features with just open-face lights, on larger productions the uneven and unfocused nature of their light makes them a poor relation of other units on the truck. They are most likely to get fired into a bounce board or used to create a little pool of light somewhere in the deep background where finesse is not needed.

Fresnel

 Arri 300W fresnel Filmgear 650W fresnel Mole Richardson 1K ‘baby’ fresnel Arri T12, a 12K fresnel

The fresnel lens was invented in the early 19th century by French physicist and engineer Augustin-Jean Fresnel in order to increase the focus and throw of lighthouse lamps. Today in the film industry, fresnel lenses can be found on tungsten, HMI and even LED fixtures.

Tungsten fresnels come in the following wattages: 150W, 300W, 650W (a.k.a. ‘tweenie’), 1K, 2K, 5K, 10K, 12K, 20K, 24K.

1Ks and 2Ks are sometimes called ‘babies’ and ‘juniors’ respectively, but confusingly those terms can also refer to whether they are the smaller location models or larger studio versions of the same wattage.

Though the fresnel lens reduces the light output a little, the beam is much more focused and can therefore create a shaft of light through smoke, which open-face lamps cannot. Hence I sometimes use tungsten fresnels to simulate hard sunlight when shooting on a stage. But beware that shadows cast by a fresnel can sometimes show up the ridges in the lens.

I often fire fresnels into bounce boards, and because their light is more focused they require less flagging to control the spill than open-face units.

On Heretiks we used numerous 300W and 650W fresnels to beef up candlelight, often placing tough-spun diffuser over them, dimming them down to warm up the colour temperature, and flickering them too.

Par (parabolic aluminised reflector)

 Par 16 (birdie) Par 38 Filmgear 4-light minibrute Mole Richardson 9-light maxibrute

Par lights use a parabolic (shaped like half a rugby ball) reflector and a lens to produce a soft-edged oval pool of light. They are extremely common in theatres, but are often used in film and TV as well.

Unlike fresnel and open-face units, par cans are referred to not by wattage but by the diameter of the bubble in eighths of an inch. So a Par 16 (a.k.a. ‘birdie’) has a 2″ bulb.

Par cans come in the following sizes: 16, 20, 36, 38, 46, 56, 64. They also come with various internal specs which affect the width of the beam.

Par cans are good for throwing shafts of light. On The Little Mermaid I used them to simulate car headlights, and as practicals (i.e. they were seen on camera) to uplight banners at the circus.

Maxibrutes (a.k.a. ‘Molepars’) are banks of multiple par 64 (1KW) lights. They come in banks of 4, 6, 9, 12 or 24. They pop up in the background of music promos quite often, because they look cool and kind of retro. I used two 9-light Maxibrutes, bounced off the tent roof, to illuminate the big top in The Little Mermaid. Some DPs like to use Maxibrutes for backlight on night exteriors. If you’re using them direct, you’ll need at least a sheet of diff to prevent multiple shadows.

Minibrutes (a.k.a. ‘fays’) are similar, but use smaller par 36 (650W) lamps.

Other

Dedolites are compact units that use a unique lens system to produce very focussed, controllable light from (most commonly) 150W bulbs. They are widely available to hire, come with in-line dimmers, and are small and light enough to be rigged overhead or in tight spots. I often use them to beef up practicals.

Source Fours or (a.k.a. ‘lekos’) are ellipsoid reflector spotlights. They feature cutters which can be used to shape the beam, they can be hired with different lenses (some of which are zoomable), and they can be fitted with gobos to project patterns. They are good for stylised pools of light or for firing into distant bounce boards without spilling light elsewhere.

Spacelights are wagon-wheel configurations of three or six 1K lamps inside a cylinder of diffusion material. They are normally used in large numbers to provide ambient toplight on stage. Click here for a brief video introduction to spacelights.

Jem Balls, or China balls, resemble Chinese paper lanterns. They come in 22″ (up to 1KW) and 30″ (up to 2KW) sizes and produce a very soft light which I personally find is never bright enough.

Bare bulbs (usually referred to as ‘globes‘) in pendant fittings can be hung from overhead or hidden behind set dressing, perhaps to beef up practicals. On Ren: The Girl with the Mark and other projects I hid some globes behind furniture to enhance the pool of light from candles.

Finally, tungsten is usually the most desirable type of bulb to use in practicals. It is commonplace when shooting a daylight interior for a spark to go around replacing the energy-saver fluorescent bulbs in the table lamps with old-school tungsten ones. The colour is much nicer, the skin tones are better as noted above, and they can be dimmed to just the right level for camera.

I’m sure I’ve missed something out – please feel free to let me know on Facebook or Twitter! Next week: HMIs.