“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

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

Robert Jezek as gameshow host Robert O’Reilly. Photo: Laura Radford

Last week saw the UK premier of The Knowledge, an art installation film, at the FLUX Exhibition hosted by Chelsea College of Arts. Conceived by award-winning, multi-disciplinary artist Ian Wolter, The Knowledge comments on the topical issue of artificial intelligence threatening jobs. It takes the form of a fake game show, pitting a team of traditional London cabbies (schooled in the titular Knowledge) against a team of smart-phoning minicab drivers. Although shot entirely on stage, the film’s central conceit is that the teams are each guiding a driver across London, to see whether technology or human experience will bring its car to the finish line first.

You can see a couple of brief promos on Vimeo here. It’s a unique project, and one that I knew would be an interesting challenge as soon as I heard of it from my friend Amanda Stekly, producer and production designer. This week and next I’ll describe the creative and technical decisions that went into photographing the piece, beginning this week with the camera side of things.

Photo: Laura Radford

I had never shot a multi-camera studio production like this before, so my first move was to sit down with my regular 1st AC and steadicam operator Rupert Peddle, and his friend Jack D’Souza-Toulson. Jack has extensive experience operating as part of a multi-camera team for live TV and events. This conversation answered such basic questions as, could the operators each pull their own focus? (yes) and allowed me to form the beginnings of a plan for crew and kit.

At the monitors with Jonnie. Photo: Laura Howard

Ian and Amanda wanted the film to have a dated look, and referenced such eighties quiz shows as 3-2-1 and Blankety Blank. Director Jonnie Howard and I knew that we had to supply the finished film in HD, which ruled out shooting on vintage analogue video cameras. Interlaced recording was rejected for similar reasons, though if memory serves, I did end up shooting at a shutter angle of 360 degrees to produce a more fluid motion suggestive of interlaced material.

I was very keen that the images should NOT look cinematic. Jonnie was able to supply two Canon C100s – which I’ve always thought have a sharp, “video-ish” look – and L-series glass. I set these to 1600 ISO to give us the biggest possible depth of field. For the remaining two cameras, I chose ENG models, a Canon XF-300 (owned by Rupert) and XF-305. In an ideal world, all four cameras would have been ENG models, to ensure huge depth of field and an overall TV look, but some compromise was necessary for budget reasons, and at least they all used Canon sensors. We hired a rack of four matching 9″ monitors so we could ensure a consistent look on set.

Photo: Laura Radford

One Canon C100, with an L-series zoom, was mounted on a pedestal and outfitted with Rupert’s follow focus system, allowing Jack to pull focus from the panning handle. The other C100 would shoot a locked-off wide, and was the first camera to be set up. A 14mm Samyang lens made the set look huge, and I placed it low down to emphasise the map in the foreground, and to make it easy for the other cameras to shoot over it. Once that frame was set, we taped a large V shape on the floor to indicate the edges of the wide shot. As long as the lights and other cameras stayed out of that area, they would be safe.

Jack operates the pedestal-mounted C100. Photo: Laura Radford

Generally Jack’s pedestal-mounted C100 followed the host, Robert Jezek, or captured the interesting moving shots, while Rupert and the third operator, Jimmy Buchanan, cross-shot the two teams on the XF-100 and XF-105. No filtration was used, except for a four-point star filter on one camera when glitter canons are fired at the end of the game. This cheesiness was inspired by the 3-2-1 clips I watched for research, in which star filters were used for the tacky sequences showing the prizes on offer.

Next week I’ll discuss lighting the show. Meanwhile, find out more about Ian’s work at ianwolter.com.

Photo: Laura Radford

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

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

Lighting with LED Screens

Gravity’s LED light box

LED lighting has found its way onto most sets now, but there is another off-shoot of LED technology which I see cropping up more and more in American Cinematographer articles. Sometimes it’s lighting, sometimes it’s a special effect, and often it’s both. I’m talking about LED screens: huge LED panels that, rather than emitting solid, constant light, display a moving image like a giant monitor.

I touched on LED Screens in my article about shooting on moving trains, and moving backgrounds do seem to be one of the most common uses for these screens. House of Cards has been in the news this week for all the wrong reasons, but it remains a useful example here. Production designer Steve Arnold describes the use of LED screens for car scenes in the political drama:

We had a camera crew go to Washington, D.C. to drive around and shoot plates for what you see outside when you’re driving. And that is fed into the LED screens above the car. So as the scene is progressing, the LED screens are synched up to emit interactive light to match the light conditions you see in the scenery you’re driving past (that will be added in post). All the reflections on the car windows, the window frames and door jambs is being shot while we’re shooting the actors in the car. Then in post the green screens are replaced with the synced up driving plates, and it works really well. It gives you the sense of light passing over the actors’ faces, matching the lighting that is in the image of the plate.

The green-screen stage used for a car scenes on House of Cards, complete with LED screens for interactive lighting.

This appears to be the go-to method for shooting car scenes now, and more exotic forms of transport are using the technique as well. Rogue One employed “a massive array of WinVision Air 9mm LED panels” to create “an interactive hyperspace lighting effect” (American Cinematographer, February 2017).

The hyperspace VFX is displayed on a huge LED screen on the set of Rogue One.

Production designer Doug Chiang comments on the use of LED screens in the Death Star command centre:

We wanted to see things on the viewscreen where traditionally it would have been a giant bluescreen; we wanted the interactive reflective quality of what you would actually see. Even though we ultimately had to replace some of those images with higher-fidelity images in postproduction, they were enough to give a sense that the quality of light on the actors and the reflections on the set looked and felt very real.

One of the first major uses of LED screens for lighting was in the seminal stranded-in-space thriller Gravity. Concerned about blending the actors convincingly with the CGI backgrounds, DP Emmanuel Lubezki, ASC, AMC came up with a solution that was, at the time, cutting-edge: “I had the idea to build a set out of LED panels and to light the actors’ faces inside it with the previs animation.” (AC, November 2013)

Gravity also featured a scene in which Sandra Bullock’s character puts out a fire, and here once again LED panels provided interactive light. This is a technique that has since been used on several other films to simulate off-camera fires, including Christopher Nolan’s Dunkirk, and the true story of the BP oil rig disaster, Deepwater Horizon.

An LED screen in use on Dunkirk

Traditionally, fire has been simulated with tungsten sources, often Maxibrutes, but on Deepwater Horizon these were relegated to background action, while foregrounds were keyed by a huge 42’x24′ video wall made up of 252 LED panels.  DP Enrqiue Chediak, ASC had this to say (in AC, October 2016):

Fire caused by burning oil is very red and has deep blacks. You cannot get that with the substance that the special effects crews use – all those propane fires are yellow. Oil fire has a very specific quality, and I wanted to reach that. It was important to feel the sense of hell.

By playing back footage of real oil fires on the video wall, Chediak was able to get the realistic colour of lighting he wanted, while retaining authentic dynamics.

The giant LED wall on Deepwater Horizon

This technique isn’t necessarily confined to big-budget productions. In theory you could create interactive lighting with an iPad. For example, a tight shot of an actor supposedly warming themselves by a fireplace; if you could get the iPad close enough, playing a video of flames, I imagine the result would be quite convincing. Has anyone out there tried something like this? Let me know if you have!

I’ll leave you with a music video I shot a few years back (more info here), featuring custom-built LED panels in the background.

Lighting with LED Screens

24 Things I Learnt from CineFest

img_1220Last week I was fortunate enough to attend the Bristol International Festival of Cinematography: five days of masterclasses and panel discussions with a range of DPs from Oscar-winners like Chris Menges, ASC, BSC and Billy Williams, BSC, OBE to emerging cinematographers like Rina Yang. It was fascinating to watch the likes of Williams lighting the purpose-built set and explaining his decisions as he went. I learnt a huge amount, so I decided to share some of the opinions and nuggets of wisdom I collected.

  • Everyone agrees that the role of the DP is being diminished. Films are more collaborative than they used to be, often with lots of input from the VFX team right from the start.

Getting Work

  • You have to create your own luck. (Rina Yang)
  • Going to LA parties and schmoozing helps. (Roberto Schaefer, AIC, ASC)
  • Each clip on your showreel should make the viewer feel something. (Matt Gray, BSC)

Prep

  • Director Philippa Lowthorpe and Gray, her DP, spent weeks of prep getting on the same page when they worked together – chatting, exchanging photos, films, and so on.
  • Spend as much time as you can with the director in the early stages of prep, because as you get closer to the shoot they will be too busy with other stuff. (Schaefer)
  • Start with ten ideas about how you want to approach the cinematography of the film. If you hang onto five of them throughout the shoot you’re doing well. (Gray)
  • Hire a gaffer who knows more than you do. (Schaefer)

Equipment

  • On Gandhi, co-cinematographer Billy Williams, BSC, OBE was granted only half of the lighting kit he asked for. That was a $22 million movie which won eight Oscars!
  • Schaefer usually carries a 24’x30′ mirror in his kit, in case he needs to get an angle from somewhere where the camera won’t fit.
  • Schaefer doesn’t used OLED monitors to light from, because the blacks are richer than they will ever be seen by an audience on any other device, including in a cinema. He won’t judge the lighting by the EVF either, only a monitor calibrated by the DIT.
  • Focus drop-off is faster on digital than on film. Hence the current popularity of Cooke lenses, which soften the drop-off.
  • Nic Knowland, BSC uses a DSLR as a viewfinder to pick his shots. He also likes to record takes on his Convergent monitor so he can review them quickly for lighting issues.

On Set

  • You have to give the actors freedom, which may mean compromising the cinematography. (Nigel Waters, BSC)
  • Gray would never ask an actor to the find the light. The light needs to find them! As soon as actors are freed from marks, they can truly inhabit the space. [Note: in my experience, some actors absolutely insist on marks. Different strokes for different folks.]
  • On digital, everyone wants to shoot the rehearsal. (Schaefer)
  • Digital encourages more takes, but more takes use up time, drains actors’ energy and creates more work for the editor. Doing fewer takes encourages people to bring their A game to take one. (Williams)
  • Director Philippa Lowthorpe prefers a DP who operates because there is no filter between the ideas you’ve discussed in prep and the operation of the camera.

Lighting

  • Sometimes when you start lighting a set, you don’t where you’re going with it. You build a look, stroke by stroke, and see where it takes you. (Knowland)
  • Williams advocates maintaining the same stop throughout a scene, because your eye gets used to judging that exposure.
  • Knowland relies more on false colours on his monitor than on his light meter.
  • Schaefer often foregoes his traditional light and colour meters for an iPad app called Cine Meter III.
  • Knowland will go to 359º on the shutter if he’s struggling for light.
  • It’s worth checking the grade on a cheap monitor or TV. That’s how most people will watch it. (Schaefer)
24 Things I Learnt from CineFest

Know Your Lights: LED

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

In this frame from Ren: The Girl with the Mark, Hunter's face is lit by a small LED reporter light hidden behind the bucket to suggest a reflection off the water.
In this frame from Ren: The Girl with the Mark, Hunter’s face is lit by a small LED reporter light hidden behind the bucket to suggest a reflection off the water.

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

LP-1x1 Bi-color LitePanel
LP-1×1 Bi-color LitePanel

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.

LP-1x1 LitePanel, set up in seconds on a lintel in a street location in Japan for the sci-fi thriller Synced.
LP-1×1 LitePanel, set up in seconds on a lintel in a street location in Japan for the sci-fi thriller Synced.

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.

Under the black bag is an LED panel to keep some consistency to the light on the actors as the car moves.
Under the black bag is an LP-1×1 LitePanel to keep some consistency to the light on the actors as the car moves, in this scene from The Gong Fu Connection.
Arri SkyPanel S60-C, the 60cm colour-tuneable model
Arri SkyPanel S60-C, the 60cm colour-tuneable model

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.

Two 6"x2" Rosco LitePads taped to the dashboard of the picture car in Above the Clouds
Two 3″x12″ Rosco LitePads taped to the dashboard of the picture car in Above the Clouds

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.

 

Arri L7-C LED fresnel
Arri L7-C LED fresnel

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

litegear-vho-pro-120-x2-literibbon-hybrid-2-e1413377188863

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.

bh1220_29962_028_resize

 

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!

Know Your Lights: LED

Know Your Lights: Fluorescent

Unusually being used as practicals, in a music promo, are a 2'x4 Kino Flo (foreground, with 3200K tubes) and a Kino Flo Diva Lite (top left, with 5500K tubes).
Unusually being used as practicals, in a music promo, are a 2’x4 Kino Flo (foreground, with 3200K tubes) and a Kino Flo Diva-Lite (top left, with 5500K tubes).

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.

Robocop (1987, dir. Paul Verhoeven) - note the fluorescent strips reflected in the suit.
Robocop (1987, dir. Paul Verhoeven) – note the fluorescent strips reflected in the suit.

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:

 

4'x4 Kino Flo with remote ballast leaning against the base of the C-stand
4’x4 Kino Flo with remote ballast leaning against the base of the C-stand
4-bank Kino Flo ballast
4-bank Kino Flo ballast

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.

 

Kino Flo Tegra
Kino Flo Tegra. You can see the integrated ballast on the back.

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 Image 87 with a silver egg crate fitted
Kino Flo Image 87 with a silver egg crate fitted
Top to bottom:
Top to bottom: 2900K, 3200K and 5500K tubes

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.

Pampa Light in action behind the scenes of Ren: The Girl with the Mark. You can see I've gelled it with Quarter Minus Green in an attempt to correct the CRI.
Pampa Light in action behind the scenes of Ren: The Girl with the Mark. You can see I’ve gelled it with Quarter Minus Green in an attempt to correct the CRI.

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.

Know Your Lights: Fluorescent

Know Your Lights: HMIs

18K bubble for an Arrimax 12/18
18K bubble for an Arrimax 18/12

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.

Arri_540817_Ballast_Electronic_2500_4000_Watts_1317042538000_325678
Arri electronic ballast for 2.5K and 4K HMIs

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.

Adjusting an Arri Daylight Compact 1200 (a 1.2K MSR) on the set of Ashes. Photo: Sophie Black
Adjusting an Arri Daylight Compact 1.2K HMI fresnel

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.

Two 18K Silver Bullet HMI fresnels rigged to a condor crane to provide moonlight for a night exterior on The Little Mermaid
Two 18K Silver Bullet HMI fresnels rigged to a condor crane to provide moonlight for a night exterior on The Little Mermaid

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

Arrilux 125W Pocket Par
Arrilux 125W Pocket Par

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.

K5600 Joker Bug 800W
K5600 Joker Bug 800W

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.

Arrimax M18
Arrimax M18

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.

Airstar helium balloons in action
Airstar helium balloons in action

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.

Again, please let me know on Facebook or Twitter if I’ve missed out any of your favourite units. Next week: fluorescents.

Know Your Lights: HMIs

“Above the Clouds”: Week 1

Principal photography has begun on my latest feature, Above the Clouds, a comedy road movie written by Simon Lord and directed by Leon Chambers. The film stars Naomi Morris as Charlie, an 18-year-old learner driver who sets off on an epic road trip from Margate to Skye with a ‘gentleman of no fixed abode’ as her responsible adult.

 

imageDay 1 / Monday

It’s a very different shoot to my last one. With a five figure budget and a total crew of about ten or twelve, we’re lean and mean. About a quarter of that crew are working for me – 1st AC Rupert Peddle and 2nd AC Max Quinton, veterans of Heretiks, and my long-serving one-man lighting team, Colin Smith. We’re shooting on an Alexa Mini. Although it’s lovely how much lighter it is than the full-size model, it’s quite fiddly. It doesn’t help that the EVF is faulty, and while we wait for a replacement Max has to change many of the settings via a smartphone app. The lenses are Arri/Zeiss Ultra Primes, my first time with these, and I’m once again using a half Soft FX filter to take off the digital edge.

We start with a dining room scene. As many of the sets will be, it’s built in director Leon Chambers’ living room, so it’s not very big. We’re prepared for this though, and Leon has purchased several Rosco Litepads in 6″x2″, 4″x4″ and 12″x12″ sizes. We stick a 4×4 to the wall behind each character as hairlights, and rig the two 6x2s, at a perpendicular angle to each other, to a flag arm. Wrapped in unbleached muslin, they’re a pleasing key.

image

After lunch we move into the shed, dressed as a young artist’s studio, complete with coloured string lights. Colin and I add three tungsten bulbs as additional practicals, plus a couple of the Litepads amongst the rafters. Outside the window we place a 4×4 kino or 2.5K HMI depending on the time of day.

 

imageDay 2 / Tuesday

Today we’re in Leon’s kitchen primarily, but with several of the scenes spilling into the hall and porch. We put our two HMIs outside the windows and initially use an LED panel on top of a cabinet and my brand new torch gaffered to the side of a cabinet to augment these for a scene that is meant to have an evening feel. Then we move onto a proper daylight scene and those have to go, to ensure all the light seems to be coming in from outside. The other reason they have to go is that we are now doing an ambitious steadicam shot which moves from the kitchen to the hall and porch, then back into the kitchen, then back into the hall and porch as characters exit the house. To the two HMIs we add the 4×4 kinoflo shining down the stairs, augmenting the natural light coming down from the landing windows. Thanks to the Alexa’s large dynamic range, we are able to accomplish the shot without any clipping, even when the door opens and when the characters move through the darkest part of the hall. The rest of the day passes in variations on the theme. I quickly find that the window positions are limiting and a fair bit of head scratching to make the angles work goes on before we wrap.

 

Day 3 / Wednesday

Back in the kitchen, one of our first scenes involves heavy smoke as a story beat. I decide to go with purely natural light, so that it’s soft enough to illuminate the smoke evenly, rather than producing shafts or pools.

After lunch we shoot a dusk scene in broad (albeit overcast) daylight. I cool down the white balance to 4300K and use a .9 soft edge graduated ND, just edging into frame, to bring down the sky a little.

Later we move to a garage, a scenario in which all the light is coming from outside through the door. Although this looks flat when the camera is looking into the garage, I decide not to fight that. When we look the other way I use matt silver bounce and a 4×4 kino to fill in.

 

Day 4 / Thursday

image

We’re on location at a roadside cafe, and I agonised long last night about how much lighting gear we should take. We don’t have transpo or security so reducing the kit means a lot less hassle for us all, though generally I prefer to have everything to hand just in case. Ultimately I decided to keep it small – just LEDs, a 4×4 kino and then flags and bounce – knowing from location photos that there will be plenty of natural light.

In fact there’s too much. The photos failed to warn me of the skylights, which take a while to block with floppy flags and Easy Up walls clipped between them. Leon has set me up for success though by choosing to shoot the scene with the windows (and therefore the key light) in the background. Flagging the skylights and ambience allows the window light to wrap around the actors in a pleasing fashion, and makes for great modelling in the close-ups, with the window light hitting the talent’s down-sides. This natural light approach requires you to work with and respond to that natural light as well, and so I embrace the appropriate ‘broken key’ look that the sun position creates on male lead Andrew, a homeless man with a troubled past. (‘Broken key’ is a term Shane Hurlbut uses to describe a key light striking the talent not quite from the side, but slightly behind.)

imageLater we shoot a scene in the Fiat 500 ‘Yellow Peril’ outside in the car park. I use a rota polar to find the perfect amount of reflection in the car windows, striking a balance between seeing some clouds (the film is called Above the Clouds after all) and seeing the characters inside.

Again the 4×4 kino proves the ideal source to bring up the light coming through the windscreen, due to its shape and softness. As shooting progresses, the sky darkens. A storm is coming. We drop the kino down to one tube, quartering the amount of key light and therefore allowing me to turn off the Alexa Mini’s internal .6 ND, bringing up the background by 2 stops and re-balancing the overall exposure. But after one more take the rain begins, and we have to wrap. Fortunately we seem to have everything we need in the can.

 

Day 5 / Friday

After watching the news in shock over breakfast, and wondering just how badly Brexit is going to screw the UK film and TV industry, we head to Leon’s for some more scenes in his living room studio. This time it’s dressed as a Travel Inn, and my lighting is motivated by the bedside practicals on the back wall. (Lighting from the back first – always a good plan.) We put a dedo above each practical and a divalite between those to give us something softer and little wrappy. The only other sources are a third practical and a Mustard Yellow gelled 1×1 LED panel outside the window, representing a streetlight. For a morning scene in the same set we put a 2.5K HMI outside the window and let the closed curtains diffuse it, with no other sources.

The set is then reconfigured into reception, and I employ a cross-backlighting set-up, with an added LED panel to represent the glow from a computer monitor.

 

imageDay 6 / Saturday

Today’s location is a tiny little mechanic’s garage in the middle of nowhere. Most of the scenes take place in the doorway, so we are at the mercy of the weather, which is incredibly changeable. Bright sunshine, cloud and heavy showers alternate throughout the day.

On the first set-up I ask to wait for cloud on at least one take because I can see from the sky that is going to be the easiest thing to match to as the day goes on. Balancing the light inside and outside the garage will also be easier in cloud, even though the Alexa’s incredible dynamic range can handle it in bright sun too.

Aside from the weather, the big challenge for me is making the shots looking into the garage have depth. The best depth is normally achieved by having the brightest area of the frame be the background, and the darkest area the foreground. Looking into the garage though, the opposite is true. But there are other ways of creating depth. One is to make pools of light with practicals, so I leave on the location’s suitably grungy fluorescents. Another is smoke, so we pump a little in and use a 2.5K HMI through a window and a 4×4 kino tucked around a corner to pick it up.

image

After dinner we have a very brief night scene to do. The blocking suggests raking the 2.5K across the front of the building which will also three-quarter-backlight the talent. Extensive experience of doing this in the past warns me that the angle of incidence could cause a massive reflection of the lamp in the shiny garage door, so I choose the lamp position carefully, and push it through an 8×8 frame of full silent grid cloth to mitigate any glare. Also this particular film seems to call for a ‘softly, softly’ approach to moonlight. It’s not fantasy, it’s contemporary comedy, so most of the time my night sources will be streetlights to keep it feeling realistic, but when I have to use moonlight as motivation I don’t want it to be hard and draw attention to itself.

The diffusion looks great, and the door is glare free, but I failed to consider the window. Fortunately Rupert spots a way to flag it. Saved by a great team!

All in all, a very productive day and a good week.

“Above the Clouds”: Week 1

4 Reasons to Use a Light Meter

lightmeterIn the celluloid era, light meters were essential to ensure proper exposure of the film negative. In today’s digital world, where you can immediately see your images on a monitor, it may seem like light meters are obsolete.

But these devices still have their place in modern cinematography. On a bigger production, when you may not be at the camera the whole time, they can be very useful. Interrupting your ACs (as they set up the sticks, swing the lens, put on the eyepiece extension, balance the fluid head, run cables to the monitors, etc.) in order to see if your image is correctly exposed on camera can be inefficient.

And having the reliable, hard number a light meter gives you can be more reassuring than judging false colours or histograms.

Here are four ways in which I used my brand new light meter on my last production, The Little Mermaid:

  1. To call ND filters. When shooting outdoors, I would take light readings in the sun and in the shade, and when then the sun was in, to understand the range of light levels I was dealing with. I could then pick an ND filter that would put me at a stop at where I would still have the room to adjust the iris a little either way if the light got brighter or darker. This was particularly important when we were shooting on water in a splash bag, when changing NDs or even just adjusting the iris was a longer process. (In my next post I’ll look deeper into stop maths and ND filters to demonstrate exactly how to select an ND filter based on a light reading.)
  2. To measure contrast ratios. The Alexa can handle up to seven stops of over-exposure and eight stops of under-exposure. Knowing this, I could use my meter to see if certain areas were going to blow out or crush, before the camera was even set up. I could also measure how many stops the key side of an actor’s face was above the fill side, and thus work out the key-to-fill ratio. At present this is still something I judge by eye on the monitor, but the more I get to know the numbers, the more I suspect I will start determining it in advance.
  3. To check green-screens are properly lit. The visual effects supervisor, Jafar, told me that green-screens should be exposed at key, or up to half a stop over key. So if I was shooting at T4, I would walk along the green-screen and take readings at various points to make sure the meter was generally giving me between f4 and f4½.
  4. To schedule a dusk shot. For a twilight scene on a beach, I needed to know in advance exactly what our window of opportunity was. Looking up the sunset time is all well and good, but it doesn’t help you figure out how long afterwards there will be enough ambient light left to shoot with. So while at location the day before, I went out onto the beach and took light readings every few minutes after sundown. These told me I had 20 minutes from sunset until the ambient light dropped below what the lenses could expose.

Do you use a light meter? And if so, how?

4 Reasons to Use a Light Meter