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!

See also: 6 Ways of Judging Exposure

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How Big a Light do I Need?

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.

Demonstrating the non-continuous spectrum of a fluorescent lamp, versus the continuous spectrum of incandescent, using a prism.

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.

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Colour Rendering Index

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

Metering the key-light. Photo: Laura Radford

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.

Note the nets mounted below the key-lights (the tallest ones). Photo: Laura Radford

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.

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

Colour Schemes

Last week I looked at the science of colour: what it is, how our eyes see it, and how cameras see and process it. Now I’m going to look at colour theory – that is, schemes of mixing colours to produce aesthetically pleasing results.

 

The Colour wheel

The first colour wheel was drawn by Sir Isaac Newton in 1704, and it’s a precursor of the CIE diagram we met last week. It’s a method of arranging hues so that useful relationships between them – like primaries and secondaries, and the schemes we’ll cover below – can be understood. As we know from last week, colour is in reality a linear spectrum which we humans perceive by deducing it from the amounts of light triggering our red, green and blue cones, but certain quirks of our visual system make a wheel in many ways a more useful arrangement of the colours than a linear spectrum.

One of these quirks is that our long (red) cones, although having peak sensitivity to red light, have a smaller peak in sensitivity at the opposite (violet) end of the spectrum. This may be what causes our perception of colour to “wrap around”.

Another quirk is in the way that colour information is encoded in the retina before being piped along the optic nerve to the brain. Rather than producing red, green and blue signals, the retina compares the levels of red to green, and of blue to yellow (the sum of red and green cones), and sends these colour opponency channels along with a luminance channel to the brain.

You can test these opposites yourself by staring at a solid block of one of the colours for around 30 seconds and then looking at something white. The white will initially take on the opposing colour, so if you stared at red then you will see green.

Hering’s colour wheels

19th century physiologist Ewald Hering was the first to theorise about this colour opponency, and he designed his own colour wheel to match it, having red/green on the vertical axis and blue/yellow on the horizontal.

RGB colour wheel

Today we are more familiar with the RGB colour wheel, which spaces red, green and blue equally around the circle. But both wheels – the first dealing with colour perception in the eye-brain system, and the second dealing with colour representation on an RGB screen – are relevant to cinematography.

On both wheels, colours directly opposite each other are considered to cancel each other out. (In RGB they make white when combined.) These pairs are known as complementary colours.

 

Complementary

A complementary scheme provides maximum colour contrast, each of the two hues making the other more vibrant. Take “The Snail” by modernist French artist Henri Matisse, which you can currently see at the Tate Modern; Matisse placed complementary colours next to each other to make them all pop.

“The Snail” by Henri Matisse (1953)

In cinematography, a single pair of complementary colours is often used, for example the yellows and blues of Aliens‘ power loader scene:

“Aliens” DP: Adrian Biddle, BSC

Or this scene from Life on Mars which I covered on my YouTube show Lighting I Like:

I frequently use a blue/orange colour scheme, because it’s the natural result of mixing tungsten with cool daylight or “moonlight”.

“The First Musketeer”, DP: Neil Oseman

And then of course there’s the orange-and-teal grading so common in Hollywood:

“Hot Tub Time Machine” DP: Jack N. Green, ASC

Amélie uses a less common complementary pairing of red and green:

“Amélie” DP: Bruno Belbonnel, AFC, ASC

 

Analogous

An analogous colour scheme uses hues adjacent to each other on the wheel. It lacks the punch and vibrancy of a complementary scheme, instead having a harmonious, unifying effect. In the examples below it seems to enhance the single-mindedness of the characters. Sometimes filmmakers push analogous colours to the extreme of using literally just one hue, at which point it is technically monochrome.

“The Matrix” DP: Bill Pope, ASC
“Terminator 2: Judgment Day” DP: Adam Greenberg, ASC
“The Double” DP: Erik Alexander Wilson
“Total Recall” (1990) DP: Jost Vacano, ASC, BVK

 

There are other colour schemes, such as triadic, but complementary and analogous colours are by far the most common in cinematography. In a future post I’ll look at the psychological effects of individual colours and how they can be used to enhance the themes and emotions of a film.

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Colour Schemes

Creating “Stasis”

Stasis is a personal photography project about time and light. You can view all the images here, and in this post I’ll take you through the technical and creative process of making them.

I got into cinematography directly through a love of movies and filmmaking, rather than from a fine art background. To plug this gap, over the past few of years I’ve been trying to give myself an education in art by going to galleries, and reading art and photography books. I’ve previously written about how JMW Turner’s work captured my imagination, but another artist whose work stood out to me was Gerrit (a.k.a. Gerard) Dou. Whereas most of the Dutch 17th century masters painted daylight scenes, Dou often portrayed people lit by only a single candle.

“A Girl Watering Plants” by Gerrit Dou

At around the same time as I discovered Dou, I researched and wrote a blog post about Barry Lyndon‘s groundbreaking candlelit scenes. This got me fascinated by the idea that you can correctly expose an image without once looking at a light meter or digital monitor, because tables exist giving the appropriate stop, shutter and ISO for any given light level… as measured in foot-candles. (One foot-candle is the amount of light received from a standard candle that is one foot away.)

So when I bought a 35mm SLR (a Pentax P30T) last autumn, my first thought was to recreate some of Dou’s scenes. It would be primarily an exercise in exposure discipline, training me to judge light levels and fall-off without recourse to false colours, histograms or any of the other tools available to a modern DP.

I conducted tests with Kate Madison, who had also agreed to furnish period props and costumes from the large collection which she had built up while making Born of Hope and Ren: The Girl with the Mark. Both the tests and the final images were captured on Fujifilm Superia X-tra 400. Ideally I would have tested multiple stocks, but I must confess that the costs of buying and processing several rolls were off-putting. I’d previously shot some basic latitude tests with Superia, so I had some confidence about what it could and couldn’t do. (It can be over-exposed at least five stops and still look good, but more than a stop under and it falls apart.) I therefore confined myself to experimenting with candle-to-subject distances, exposure times and filtration.

The tests showed that the concept was going to work, and also confirmed that I would need to use an 80B filter to cool the “white balance” of the film from its native daylight to tungsten (3400K). (As far as I can tell, tungsten-balanced stills film is no longer on the market.) Candlelight has a colour temperature of about 1800K, so it still reads as orange through an 80B, but without the filter it’s an ugly red.

Meanwhile, the concept had developed beyond simply recreating Gerrit Dou’s scenes. I decided to add a second character, contrasting the historical man lit only by his candle with a modern girl lit only by her phone. Flames have a hypnotic power, tapping into our ancient attraction to light, and today’s smartphones have a similarly powerful draw.

The candlelight was 1600K warmer than the filtered film, so I used an app called Colour Temp to set my iPhone to 5000K, making it 1600K cooler than the film; the phone would therefore look as blue as the candle looked orange. (Unfortunately my phone died quickly and I had trouble recharging it, so some of the last shots were done with Izzi’s non-white-balanced phone.) To match the respective colours of light, we dressed Ivan in earthy browns and Izzi in blues and greys.

Artemis recce image

We shot in St. John’s Church in Duxford, Cambridgeshire, which hasn’t been used as a place of worship since the mid-1800s. Unique markings, paintings and graffiti from the middle ages up to the present give it simultaneously a history and a timelessness, making it a perfect match to the clash of eras represented by my two characters. It resonated with the feelings I’d had when I started learning about art and realised the continuity of techniques and aims from me in my cinematography back through time via all the great artists of the past to the earliest cave paintings.

I knew from the tests that long exposures would be needed. Extrapolating from the exposure table, one foot-candle would require a 1/8th of a second shutter with my f1.4 lens wide open and the Fujifilm’s ISO of 400. The 80B has a filter factor of three, meaning you need three times more light, or, to put it another way, it cuts 1 and 2/3rds of a stop. Accounting for this, and the fact that the candle would often be more than a foot away, or that I’d want to see further into the shadows, the exposures were all at least a second long.

As time had become very much the theme of the project, I decided to make the most of these long exposures by playing with motion blur. Not only does this allow a static image – paradoxically – to show a passage of time, but it recalls 19th century photography, when faces would often blur during the long exposures required by early emulsions. Thus the history of photography itself now played a part in this time-fluid project.

I decided to shoot everything in portrait, to make it as different as possible from my cinematography work. Heavily inspired by all the classical art I’d been discovering, I used eye-level framing, often flat-on and framed architecturally with generous headroom, and a normal lens (an Asahi SMC Pentax-M 50mm/f1.4) to provide a natural field of view.

I ended up using my light meter quite a lot, though not necessarily exposing as it indicated. It was all educated guesswork, based on what the meter said and the tests I’d conducted.

I was tempted more than once to tell a definite story with the images, and had to remind myself that I was not making a movie. In the end I opted for a very vague story which can be interpreted many ways. Which of the two characters is the ghost? Or is it both of them? Are we all just ghosts, as transient as motion blur? Do we unwittingly leave an intangible imprint on the universe, like the trails of light my characters produce, or must we consciously carve our mark upon the world, as Ivan does on the wall?

Models: Izzi Godley & Ivan Moy. Stylist: Kate Madison. Assistant: Ash Maharaj. Location courtesy of the Churches Conservation Trust. Film processing and scanning by Aperture, London.

Creating “Stasis”

The Inverse Square Law

If you’ve ever read or been taught about lighting, you’ve probably heard of the Inverse Square Law. It states that light fades in proportion to the square of the distance from the source. But lately I started to wonder if this really applies in all situations. Join me as I attempt to get to the bottom of this…

 

Knowing the law

The seed of this post was sown almost a year ago, when I read Herbert McKay’s 1947 book The Tricks of Light and Colour, which described the Inverse Square Law in terms of light spreading out. (Check out my post about The Tricks of Light and Colour here.)

But before we go into that, let’s get the Law straight in our minds. What, precisely, does it say? Another excellent book, Gerald Millerson’s Lighting for Television and Film, defines it thusly:

With increased distance, the light emitted from a given point source will fall rapidly, as it spreads over a progressively larger area. This fall-off in light level is inversely proportional to the distance square, i.e. 1/d². Thus, doubling the lamp distance would reduce the light to ¼.

The operative word, for our purposes, is “spreads”.

If you’d asked me a couple of years ago what causes the Inverse Square Law, I probably would have mumbled something about light naturally losing energy as it travels. But that is hogwash of the highest order. Assuming the light doesn’t strike any objects to absorb it, there is nothing to reduce its energy. (Air does scatter – and presumably absorb – a very small amount of light, hence atmospheric haze, but this amount will never be significant on the scale a cinematographer deals with.)

In fact, as the Millerson quote above makes clear, the Inverse Square Law is a result of how light spreads out from its source. It’s purely geometry. In this diagram you can see how fewer and fewer rays strike the ‘A’ square as it gets further and further away from the source ‘S’:

Illustration by Borb, CC BY-SA 3.0

Each light ray (dodgy term, I know, but sufficient for our purposes) retains the same level of energy, and there are the same number of them overall, it’s just that there are fewer of them passing through any given area.

So far, so good.

 

Taking the Law into my own hands

During season two of my YouTube series Lighting I Like, I discussed Dedo’s Panibeam 70 HMI. This fixture produces collimated light, light of which all the waves are travelling in parallel. It occurred to me that this must prevent them spreading out, and therefore render the Inverse Square Law void.

This in turn got me thinking about more common fixtures – par cans, for example.

 

Par lamps are so named for the Parabolic Aluminised Reflectors they contain. These collect the light radiated from the rear and sides of the filament and reflect it as parallel rays. So to my mind, although light radiated from the very front of the filament must still spread and obey the Inverse Square Law, that which bounces off the reflector should theoretically never diminish. You can imagine that the ‘A’ square in our first diagram would have the same number of light rays passing through it every time if they are travelling in parallel.

Similarly, fresnel lenses are designed to divert the spreading light waves into a parallel pattern:

Even simple open-face fixtures have a reflector which can be moved back and forth using the flood/spot control, affecting both the spread and the intensity of the light. Hopefully by now you can see why these two things are related. More spread = more divergence of light rays = more fall-off. Less spread = less divergence of light rays = more throw.

So, I wondered, am I right? Do these focused sources disobey the Inverse Square Law?

 

Breaking the law

To find the answer, I waded through a number of fora.

Firstly, and crucially, everyone agrees that the Law describes light radiated from a point source, so any source which isn’t infinitely small will technically not be governed by the Law. In practice, says the general consensus, the results predicted by the Law hold true for most sources, unless they are quite large or very close to the subject.

If you are using a softbox, a Kinoflo or a trace frame at short range though, the Inverse Square Law will not apply.

The above photometric data for a Filmgear LED Flo-box indeed shows a slower fall-off than the Law predicts. (Based on the 1m intensity, the Law predicts the 2m and 3m intensities as 970÷2²=243 lux and 970÷3²=108 lux respectively.)

A Flickr forum contributor called Severin Sadjina puts it like this:

In general, the light will fall off as 1/d² if the size of the light source is negligible compared to the distance d to the light source. If, on the other hand, the light source is significantly larger than the distance d to the light source, the light will fall off as 1/d – in other words: slower than the Inverse Square Law predicts.

Another contributor, Ftir, claims that a large source will start to follow the Law above distances equal to about five times the largest side of the source, so a 4ft Kinoflo would obey the Law very closely after about 20ft. This claim is confirmed by Wikipedia, citing A. Ryer’s The Light Measurement Handbook.

But what about those pesky parallel light beams from the pars and fresnels?

Every forum had a lot of disagreement on this. Most people agree that parallel light rays don’t really exist in real life. They will always diverge or converge, slightly, and therefore the Law applies. However, many claim that it doesn’t apply in quite the same way.

Diagram from a tutorial PDF on light-measurement.com showing a virtual point source behind the bulb of a torch.

A fresnel, according to John E. Clark on Cinematography.com, can still be treated as a point source, but that point source is actually located somewhere behind the lamp-head! It’s a virtual point source. (Light radiating from a distant point source has approximately parallel rays with consequently negligible fall-off, e.g. sunlight.) So if this virtual source is 10m behind the fixture, then moving the lamp from 1m from the subject to 2m is not doubling the distance (and therefore not quartering the intensity). In fact it is multiplying the distance by 1.09 (12÷11=1.09), so the light would only drop to 84% of its former intensity (1÷1.09²=0.84).

I tried to confirm this using the Arri Photometrics App, but the data it gives for Arri’s fresnel fixtures conforms perfectly with an ordinary point source under the Law, leaving me somewhat confused. However, I did find some data for LED fresnels that broke the Law, for example the Lumi Studio 300:

As you can see, at full flood (bottom graphic) the Law is obeyed as expected; the 8m intensity of 2,500 lux is a quarter of the 4m intensity of 10,000 lux. But when spotted (top graphic) it falls off more rapidly. Again, very confusing, as I was expecting it to fall off less rapidly if the rays are diverging but close to parallel.

A more rapid fall-off suggests a virtual point source somewhere in front of the lamp-head. This was mentioned in several places on the fora as well. The light is converging, so the intensity increases as you move further from the fixture, reaching a maximum at the focal point, then diverging again from that point as per the Inverse Square Law. In fact, reverse-engineering the above data using the Law tells me – if my maths is correct – that the focal point is 1.93m in front of the fixture. Or, to put it another way, spotting this fixture is equivalent to moving it almost 2m closer to the subject. However, this doesn’t seem to tally with the beam spread data in the above graphics. More confusion!

I decided to look up ETC’s Source Four photometrics, since these units contain an ellipsoidal reflector which should focus the light (and therefore create a virtual point source) in front of themselves. However, the data shows no deviation from the Law and no evidence of a virtual point source displaced from the actual source.

 

I fought the law and the law won

I fear this investigation has left me more confused than when I started! Clearly there are factors at work here beyond what I’ve considered.

However, I’ve learnt that the Inverse Square Law is a useful means of estimating light fall-off for most lighting fixtures – even those that really seem like they should act differently! If you double the distance from lamp to subject, you’re usually going to quarter the intensity, or near as damn it. And that rule of thumb is all we cinematographers need 99% of the time. If in doubt, refer to photometrics data like that linked above.

And if anyone out there can shed any light (haha) on the confusion, I’d be very happy to hear from you!

The Inverse Square Law

Front-light

A front-lit shot of mine from “The First Musketeer” (2015, dir. Harriet Sams)

Front-light is a bit of a dirty word in cinematography. DPs will commonly be heard rhapsodising about beautiful backlight or moody sidelight, but rarely does the humble front-light get any love. But there is no right or wrong in cinematography. Just because front-light is less popular, doesn’t mean it can’t make a great shot.

Why do we avoid front-light so often? Because it usually flattens things out, reducing or eliminating any sense of depth in the image, and giving no shape to faces or objects. Sometimes this might be the perfect look: for a character who is shallow, or who feels like their life is dull and uneventful, perhaps; a live-action scene to be intercut with two-dimensional animation; or a stylised flashback like the image above. And sometimes, of course, front-light is unavoidable for logical reasons – if a character is looking out of a window, say. The trouble is, it can make for un-engaging or un-cinematic images, and that’s when you may want to pull some other tricks out of the box.

Here are six ways to bring some interest back into a frontally-lit frame.

 

1. Cut the light.

A shot of mine from “Crossing Paths” (2015, dir. Ben Bloore)

If you can flag some of the front-light, reducing the area of the frame it’s hitting, and leave the rest to the fill light or to fall into shadow, you’ll get some contrast back into your image.

 

2. Use a gobo.

Another shot of mine, this one from “Lebensraum” way back in 2007.

If it doesn’t make sense to cut the light, try breaking it up with a gobo. You can make a gobo from almost anything. Commonly on night exteriors I send a spark off to liberate a branch from a nearby tree and rig that in front of the key-light. If I need to create a window-frame effect I’ve been known to clamp a chair or stool to a C-stand to get a suitable pattern of perpendicular lines.

 

3. Add dynamics.

Front-light is often more interesting if it’s not there all the time. If you can find an excuse to have it flicker or move somehow, you’ll get a lot more mood and shape in your shot. Firelight, TVs, rippling water, panning searchlights or the headlights of a passing car can all safely come from the front and remain dramatic. Create a moving gobo and you’ve got something really interesting. The tree branch example from earlier – if that blows around in the wind then it will add a lot of tension to the visuals. Here’s a firelight example from Ren: The Girl with the Mark

(Check out my Instagram feed for more lighting breakdowns like this.)

 

4. Darken the background.

“Magnolia” (DP: Robert Elswit, ASC)

You can combat the lack of depth by keeping the background dark, so that the front-lit subject stands out against it. This will happen automatically due to the Inverse-square Law (a post on that is coming soon) if the subject is close to the source, e.g. standing right by a window. Due to the nature of front-light, you probably can’t flag the background without flagging the subject too, so bringing your source closer to the subject or redressing the background may be your only options.

 

5. Make a virtue of the subject’s shadow.

“The Shadow of Death” by William Holman Hunt, 1873

One reason to avoid front-light is the distracting shadow which the subject will cast on the background. But sometimes this can be a great benefit to the shot, almost becoming another character, or adding subtext as in this painting.

 

6. Use a strong backlight.

A still of mine from “Stop/Eject”. The red backlight and the kicker from the practical help mitigate the flat front-light.

If there’s nothing you can do to modify the front-light, then pumping up the backlight might well save the day. The most flatly-illuminated shots suddenly become deep and appealing when the subject has a halo of over-exposed light. Indeed, this is what commonly happens with day exteriors: you shoot into the sun to get the nice backlight, and ambient light flatly fills in the faces.

So next time you’re faced with front-light, remember, it’s not the end of the world!

Front-light

#ShotOfTheWeek: 2017 Round-up

At the end of last summer I started a regular #ShotOfTheWeek on my Twitter feed. It’s very simple: each week I post a frame grab (or sometimes a GIF if I can find one) of a great shot from a film or series I’ve been watching. Sometimes these are new productions, just out, and sometimes they’re older pieces which I’m revisiting or viewing for the first time.

For those of you who aren’t among the Twitterati, here is a round-up of last year’s Shots of the Week. On the other hand, if you are a Twitterist, why not post your own inspirational frame grabs, using the hashtag #ShotOfTheWeek?

 

Powerful Close-ups

Cinema is arguably at its most potent  when showing us the tiny nuances of emotion that only a big close-up can provide.

“Anne with an E” DP: Bobby Shore

This example from the moving Netflix series Anne with an E makes the most of Anne’s freckled face and puts us right in her headspace… literally. Shots like this were captured with a 27mm Primo, as opposed to the vintage Panavision glass used for other coverage. For more on the cinematography of Anne with an E, check out the Varicam section in my report from Camerimage 2017.

“Black Narcissus” DP: Jack Cardiff

I love the shadows in this shot by legendary DP Jack Cardiff; they almost suggest a crucifix or prison bars. Either would be appropriate for this story of a nun sent to a remote Indian palace to establish a school and hospital. The low-angle eye-light adds to the unsettling feel.

“The Crown” DP: Stuart Howell

The key promotional art for The Crown is an edge-lit profile shot of the Queen, evoking the regal image on stamps and coins. Here DP Stuart Howell has paid homage to the artwork, channelling the same connotations of a figurehead carrying a country on her shoulders.

“American Gods” DP: Aaron Morton

What can I say? I’m a sucker for a good profile shot. The hellish colours here are perfect given what the erstwhile Lovejoy has just done. (I won’t give you any spoilers, but let’s just say it doesn’t involve cheeky antiques dealing.)

 

Symbolism

“The Handmaid’s Tale” DP: Colin Watkinson

This was the shot that inspired me to start #ShotOfTheWeek. The Handmaid’s Tale is set in a Christian fundamentalist society, so evoking classical religious paintings with the angel-wing-like headboard and the muted, brown colour scheme was a clever move.

“The Ipcress File” DP: Otto Heller

This classic spy thriller has a lot of unusual compositions with domineering foreground objects. Here the cross and circle shapes of the light-shade suggest the crosshairs of a gun, while the bulb tastefully obscures the actual bullet wound.

“Mr Robot” DP: Tod Campbell

This one is almost too on-the-nose to be called symbolism. Only a drama as quirky as Mr Robot could get away with this kind of (literal) signposting, but I love how bold it is. The rigid geometric lines and excessive headroom used throughout the series are also in evidence here, reflecting how we’re seeing everything from Elliot’s mentally ill point of view.

 

Negative Space

“Mission: Impossible – Rogue Nation” DP: Robert Elswit

A forgettable film, but a shot with much to admire. The dark back of the bench creates negative space in the composition, reducing the already-wide Scope frame to a ratio of about 4:1, echoing the short, wide shape of the House of Commons. On the lighting front, negative fill has been employed to render both that bench and the cast very dark, almost silhouettes, imparting a lot of depth to an otherwise flat image.

“Stranger Things” DP: Tim Ives

Again, negative space here creates a geometrical frame within a frame. What I particularly liked was the placement of the bulb above the sheriff’s head, rather than on the right of frame, which would have produced a more balanced but much less interesting shot.

“Better Call Saul” DP: Arthur Albert

Every time Better Call Saul returned to this location I scanned the background of each angle, trying to figure out what on earth could be motivating the bold slash of light on the right of this image. It remains a mystery! The show is full of uncompromisingly dark images with crisp, pure blacks, but perhaps none so overtly noirish as this one.

 

Intersecting Lines

“Metropolis” DPs: Karl Freund, Günther Rittau & Walter Ruttmann

All credit to Otto Hunte, the production designer on this 1920s sci-fi classic, as every line in this set leads us to the figure of Maria, fittingly for a character who has captured the imaginations of the dystopian underclass. The cinematographers have helped by framing her centrally and making her the brightest part of the image.

“Jardin d’hiver” DP: Darius Khondji

Jardin d’hiver was sponsored by CW Sonderoptic to promote their new large-format Leica Thalia glass (see my Camerimage post for more info). I have to admit that most of the film’s imagery did nothing for me, but this shot of bold, contrasty lines softened by the milkiness of the foreground window has a graphical quality I find very appealing.

“Little Miss Sunshine” DP: Tim Suhrstedt

This is a shot of two halves: the upper half busy, confused and oppressive, the lower half reassuringly simple with its one-point perspective. It was only after filming wrapped on Above the Clouds that I realised just how much this shot and others like it in Little Miss Sunshine had influenced my cinematography of Leon Chambers’ comedy road movie. (Check out the second still on the Above the Clouds page and you’ll see what I mean!)

 

Iconic Reveals

“The 39 Steps” (1935) DP: Bernard Knowles

Richard Hannay and the audience both discover the cause of Annabella’s distress simultaneously, in a reveal that’s shocking and also funny! The chiaroscuro of the lighting beautifully highlights the bright knife against the deep shadows of the background.

“Terminator 2: Judgment Day” DP: Adam Greenberg

These two gifs are both parts of the same shot, which cranes up from the shockingly unexpected crushing of the skull to reveal the endoskeleton puppet in mid-shot as a perfectly timed explosion goes off in the background. As well as being a remarkable technical achievement, the arts and sciences of cinematography, practical effects and animatronics all working in harmony, it’s a great piece of visual storytelling.

 

And finally…

“A Ghost Story” DP: Andrew Droz Palermo

A Ghost Story didn’t get a very wide release, and won’t be to everyone’s taste. A lyrical meditation on the nature of time, its slow pace becomes glacial during a grief-filled, ten-minute pie-eating scene containing only one cut. There is plenty of time to consider the composition, and I loved how casually the ghost is placed within the frame, with the top of his head even cut off. (I later discovered he was composited in, to reduce the chances of anything spoiling the ultra-long, ultra-emotional take.) The lines of the cupboards lead our eyes always back to Rooney Mara, the painterly splash of light on the wall (which I believe was natural) throwing her profile into relief. When she starts to cry, it takes a while to spot the tears, but somehow that makes it all the more powerful.

It’s interesting to note that no fewer than four aspect ratios are represented by all these Shots of the Week: from the traditional Academy ratio of 4:3, through the standard 16:9, to the Netflix-favoured 2:1 and of course 2.39:1 Cinemascope. It’s an exciting time to be working in cinematography, when we have so many choices open to us to create the most fitting images for any given story. Here’s to many more inspiring #ShotOfTheWeek images in 2018. Follow me on Twitter to see them first!

#ShotOfTheWeek: 2017 Round-up

A Cinematograper Prepares

One of the things which I believe separates a good director of photography from a bad one is preparation. On a big production you may have weeks of paid, full-time prep, but on a micro-budget movie you may be lucky to have a single meeting before the shoot. In the latter case you’ll have to use your initiative, put in the time for free, and use Skype a lot, but either way the quality of the prep can make or break the production.

Here are ten things a DP should do to set themselves up for success before the camera rolls. This is not intended to be an exhaustive list, rather it’s a run-down of the things which I have found to bear most fruit later on in the production.

 

1. Get inside the director’s head.

Some directors will come to you with a beautiful set of storyboards, concept art and reference images, but many won’t. Many will simply have an idea in their head of how they want it to look, and it’s your job to find out what that vision is. Often this will happen before full-time prep begins. It will consist of watching movies together, pouring over books of photos, sharing Pinterest boards or Dropboxes full of images, all the while discussing what they do and don’t like. The aim is to get such a clear idea of their vision that when you set up a shot you’ll deliver the mood they’re looking for first time.

 

2. Work with the art department.

Chatting over a set model helps identify potential lighting or lensing problems before construction begins.

The next person to get in sync with is the production designer. This is an incredibly important and symbiotic relationship; you have the power to completely destroy each others’ work, or to make each other look like geniuses! Two things you should talk about early on with the designer are the colour palette of the film (and any palettes specific to certain locations, plot threads or characters) and the aspect ratio: does the shape of the sets being designed fit the shape of the frame you’re planning to compose? Next you’ll want to discuss each set and the position of windows and practicals within it, to ensure that you’ll be able to get the lighting angles you need. For their part, the designer will want to quiz you on where the key camera positions will be, and the rough lens lengths you’ll be using, so they know where to put in the most detail and the important bits of dressing.

 

3. Get to know the needs of the other H.o.D.s.

Although the production designer is the most important head of department for a DP to work with, they are by no means the only one. The visual effects supervisor is increasingly a key collaborator; you should discuss the look you’re going for and how that will integrate with the VFX, and whether plates need to be shot at a higher resolution, in RAW, or any other technical requirements. You should familiarise yourself with the costume designs and discuss how those will integrate with the overall look. Similarly the make-up department will want to talk about about lens filtration, coloured lighting and anything else that may affect how their work looks. The line producer is a crucial person to get on the good side of. Sooner or later you’ll have to ask them for something expensive and unexpected, and they’re much more likely to say yes if you have tried to help them earlier on, by reducing your equipment list for example, or by hiring local camera assistants to save on accommodation costs.

Read my article on collaborating with other departments for more on this topic.

 

4. Check sun paths at locations.

Checking my compass at the stone circleWhen you start to scout the locations, you’ll want to pay careful attention to the direction of the sun. Which windows will it come through as it moves around over the course of the day? Are those trees or buildings likely to shadow that park bench where the characters will be sitting? With a bit of experience – and a compass, if it’s cloudy – you can estimate this, or use apps like Sun Tracker and Helios which are designed for exactly this purpose. For interiors, windows that never get direct sunlight are most convenient, allowing you to light them artificially, and thus constantly, without having to flag the real sun. For exteriors, shooting into the sun is generally most desirable, for the beauty of the backlight and the softness of the reflected fill. Of course, there will always be compromises with the other demands of the production.

See my article on sun paths for more on this.

 

5. Develop the shot list with the director.

Each director has a different process, but often they will draft a shot list on their own before passing it to you for feedback. There are many things for a DP to consider when going through this list. Do the shots reflect the style and visual grammar you both discussed earlier? (If not, has the director had a change of heart, or have they simply forgotten? Directors have a lot to think about!) Do the shots provide enough coverage for the editor? Are there too many shots to realistically accomplish on schedule? (Very often there are!) What grip equipment will the camera movements require? Are any special lenses or filters required, e.g. a macro lens for an extreme close-up of an eye?

 

6. Shoot tests.

Testing is a crucial part of the prep for both technical and creative reasons. Usually you will want to test a few different cameras and lens sets, to see which best serve the story. For example, a period film lit with a lot of genuine candlelight may work best on a sensitive camera like the Panasonic Varicam combined with soft fall-off lenses like Cooke S4s, while a sci-fi thriller might be suited to a Red or Alexa and a set of anamorphics for those classic flares. Until you’ve tested them and compared the images side by side though, you can’t be sure, and neither can the director and producers. Often costume and make-up tests will be requested, which may be combined with the camera tests to see how the different sensors render them, or maybe done separately once the camera kit is locked down. These tests are also a great opportunity for the DP to demonstrate for the director the type of lighting you plan to use to, and to make sure you really are on the same page. Ideally a DIT (digital imaging technician) will be available to grade the test footage, developing LUTs (look-up tables) if required, and providing proof of concept for the finished look of the movie.

Check out my tests of Alexa ISO settings, spherical lenses and anamorphic lenses.

 

7. Discuss the schedule.

Once the 1st AD has drafted the shooting schedule, they will show it to the DP for feedback. When determining how much can be done in a day, the 1st AD is thinking of the script page count, and they may not have seen a shot list at this point. Along with the director, the DP must bring any concerns they have about the schedule to the 1st AD in prep, or forever hold your peace! Is there enough time to get those tricky camera moves you’ve planned? Has the re-light time for the reverse been factored in? Have things been arranged in a logical order for lighting, or will things have to be torn down and put back up again later? Does the schedule permit things to be shot at the best time of day for light? Are the night scenes actually scheduled at night or will the windows have to be blacked out? Are there critical close-ups towards the end of the schedule, when the cast will be tired and no longer look their best?

For more detail on this, check out my article about things to look for in a schedule.

 

8. Get to know the faces of your cast.

Legendary DP John Alton, ASC tests lighting angles with Joan Bennett

However good-looking the talent may be, they will always look better under certain types of lighting than others. Often you will figure out what suits each actor after a week or so of shooting, but ideally you want to find out before principal photography begins. You can do this during testing, if the cast are available and you have enough time – trying out different key angles, fill levels, backlight and lenses to see what works best for their individual faces. Apart from anything else, this is a great way to establish trust with the cast right from the start, assuring them that they are in safe hands. If testing isn’t possible, watch some of their previous work, looking carefully at how they have been photographed.

 

9. Mark up your script.

There’s no point in having lots of great ideas in preproduction if you forget them when you’re on set. Everyone has a different system, but you may wish to mark up your script and/or shot list. This could include using coloured highlighters to differentiate day and night scenes at a glance, underlining any references to mood or camera angles in the stage directions, or indicating beats in the development of the story or characters which need to be reflected in how things are lit or shot.

 

10. Plan your lighting.

Shop lighting planEveryone likes to get rolling as soon as possible after call time, and a big factor in achieving this is how quickly you can light. Ideally you will have planned the broad strokes of the lighting in preproduction, and communicated that plan to the gaffer. Budget permitting, the lighting crew can even pre-rig the set so that only tweaking is required when the whole unit arrives. In this case you’ll need to have been very clear and specific about what you want set up and where, drawing diagrams or approving those which the gaffer has drawn up. Often you’ll need to know the rough blocking of the scene before you can plan the lighting, so you should make sure the director indicates their intentions for this during scouts.

 

Every film is different, but follow the steps above and you’ll be well on your way to an efficient and productive shoot in 2018. Happy new year!

A Cinematograper Prepares

Introduction to Short Key Lighting

“The Lord of the Rings: The Fellowship of the Ring” – DP: Andrew Lesnie, ACS, ASC

If you’re starting out in your cinematography career, or maybe stepping up from camera operation,  lighting can be daunting. How do you know where to put your lights? If you’re working to the Three Point Lighting system, the backlight is self-explanatory, and the fill will often be ambient and directionless, but you may still be left wondering where to put your main light source, your key.

Fortunately there is a very simple rule of thumb, known as short key. In simple terms, a short key light is one which is on the opposite side of the subject’s eye-line to the camera. Let’s delve into what this means and why it’s so common. In fact, once you understand what a short key is you’ll be forever spotting examples of it in film and TV – you’ll be staggered at how often it’s used.

It’s easiest to think of short key from the perspective of the actor. The camera is in front of us and off to one side, because very rarely do actors look down the lens, and the key light is in front of us and off to the other side. It’s called short key because the side of our face that it hits is the side away from camera. The opposite of short key is broad key, where the light is on the same side of us as the camera, thus lighting the “broad” side of our face, the side presented to camera. Note that the light can be either side of the camera, it’s which side of our eye-line it’s on that’s important.

“Arrival” – DP: Bradford Young, ASC

Short key follows the general cinematography principle that light is more interesting when it comes in from the side and behind, rather than from close to camera. It’s preferred by most DPs in most situations because it produces more dimensionality and contrast than broad key. By hitting the side of the face away from camera, a short key leaves shadow on the closer side, creating mood and interest. It brings out the shape of the nose and cheeks. It leaves the ear and side of the head darker, concentrating attention on the face and consequently the performance.

Under the umbrella of short key we can still vary the angle tremendously to affect the mood. If we place the key severely to the side, so none of its illumination reaches the camera side of the actor’s face, and use a very low level of fill, we create a strong, uncompromising look.

“Logan” – DP: John Mathieson, BSC
“Fight Club” – DP: Jeff Cronenweth, ASC

If we place the key closer to front-on, and soften it with diffusion so that it wraps around the camera side of the face, we create a more comfortable, flattering look.

“Skyfall” – DP: Roger Deakins, ASC, BSC, CBE
“The Pianist” – DP: Pawel Edelman, PSC

We can also raise the lamp to shade the eye sockets, Godfather style, lower it to create a campfire ghost story look, or place it anywhere in between.

Broad key is less desirable amongst cinematographers, often resorted to only when short key cannot be reconciled with motivating the sources authentically. However, that doesn’t mean that it’s bad or that it can’t be used deliberately and creatively. Here’s just one example of broad key being used extremely effectively.

An example of broad key from “Amélie” – DP: Bruno Delbonnel, AFC, ASC

Short key though is the dominant, ubiquitous style of lighting. It is often the first thing a DP considers when walking onto the set: where can I put the key light in order to hit the short side of the talent? Or conversely, where can I put the camera so that it’s on the opposite side to the light?

If we’re dealing with fixed light sources like windows, or shooting outdoors – we’ll exploit the sun-path or even request that the blocking be altered to ensure a short key.  It can go such a long way to making an image cinematic.

“La La Land” – DP: Linus Sandgren, FSF
“Titanic” – DP: Russell Carpenter, ASC

In standard dialogue scenes with two characters facing each other, a technique called cross-backlighting is commonly used to short key both characters and provide backlight too. Check out my post on cross-backlighting for more info.

So next time you watch TV or a movie, look out for short key lighting; I guarantee you’ll see it everywhere.

The frame grabs in this post are from The Cinematographer Index. Check out this very useful resource showcasing great cinematography, and donate a few quid if you can.

Introduction to Short Key Lighting