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Advice on lighting a bus interior at night


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#1 gustavo godinho

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Posted 04 March 2009 - 11:17 AM

I'm thinking about adding fluorescent lamps on its ceiling, maybe 3x the actual amount and achieving some gain if necessary. It's very important to have some reference of the city lights through the windows. What else would you guys do in a very low budget production? We're shooting Sony EX1 + M2.
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#2 Ralph Keyser

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Posted 04 March 2009 - 05:18 PM

I'm thinking about adding fluorescent lamps on its ceiling, maybe 3x the actual amount and achieving some gain if necessary. It's very important to have some reference of the city lights through the windows. What else would you guys do in a very low budget production? We're shooting Sony EX1 + M2.


I was on a shoot last year that used Kinoflos clamped to the overhead rails on the bus. A pair of portable generators on the bike rack up front provided the power.
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#3 Adrian Sierkowski

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Posted 04 March 2009 - 05:23 PM

I would perhaps avoid the M2... it eats a lot of light (2 stops IIRC) and rather look into a Letus.
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#4 DS Williams

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Posted 05 March 2009 - 03:25 AM

Yes, I second that notion. The original m2 is a no-go. Look into their newest adapter, the Encore I believe it's called. Spinning GG and not as much light stealing.

You know..it's not that hard to get shallow DOF in 1/2" chips, you just need distance.
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#5 Jose Figueroa Baez

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Posted 05 March 2009 - 10:06 AM

You know..it's not that hard to get shallow DOF in 1/2" chips, you just need distance.


I think thats is a great suggestion. Place your camera as far back as you can from your subject and zoom in. This will give you great DOP on that size chip. In terms of the lighting, I think you are on to something with the overhead fluorescents. If you can pull off the DOP without the M2 and gain those 2 stops, I think you'll have more light to manage and will give you more freedom. Make sure you measure the outside and light accordingly inside in order to get those outside lights you mentioned. Good luck man.
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#6 Ram Shani

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Posted 06 March 2009 - 10:15 AM

HI

i use the kino tape to the ceiling of the bus at a music video i shoot

it work great i had another barfly200 i used to add a little tweak for the eyes or contras to the face

even if the kino were in the frame like in a long shot they look like the bus lamp

BTW

changing the distance of the cam and zooming in only change the apprent out off focus. it doesn't change the dof

it is beater to work with as open f/stop as you can and move your subject as far as you can from the background
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#7 Eileen Ryan

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Posted 09 November 2009 - 08:42 AM

I'm thinking about adding fluorescent lamps on its ceiling, maybe 3x the actual amount and achieving some gain if necessary. It's very important to have some reference of the city lights through the windows. What else would you guys do in a very low budget production? We're shooting Sony EX1 + M2.


If you are talking about adding “3x the actual amount” of fluorescent tubes that are already in the bus, you are talking about a fairly large electrical load that you will have to power somehow. Another alternative to rigging a generator outside the bus is a Battery/Inverter set up that is commonly called a "Battverter." A "Battverter" system consists of a deep cycle 12V DC power source (usually Marine Cells), a 12V DC-to– 120V AC True Sine Wave Power Inverter, and a Battery Charger. Battverters can work great for traveling car shots but offer limited capacity and run time. The largest true sine wave inverter I have seen is 1800W which is just enough to run a few Kinos. Your run time will depend on how many batteries you wire in paralell. Here are some production stills that show you two Battverter systems we built to run kinos to light the inside of an airport shuttle bus for the feature "Shuttle." The first is a 750W "Batt-Verter" rig wired into in Calzone case and mounted on a Exo-skeletal pipe rig that also held Kino Flos.

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Exo-skeletal pipe rig on shuttle to rig lights and mount 750W batt-verter on front (covered for rain protection)

To maximize the running time on however many batteries you use, I would suggest you make up a "jumper cable" to attach to the leads of the bus’ alternator. That way you can use the bus alternator as a generator to run the lights during set up and rehearsals. When it comes time to shoot, shut off the engine and continue to run the lights on the silent Battverter alone. Running the vehicle engine between takes charges the batteries so that they will run longer.

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750W "Batt-Verter" Rig wired into in Calzone case and tied into the Shuttle’s alternator

The production stills below show you a more elaborate 1800W Battverter system that we built to run 16 - 4’ kinos tubes inside the airport shuttle bus. Use this link - http://www.screenlig...emailintro.html -
for details on how we wired it into the shuttle bus.

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1800W "Batt-Verter" Rig wired into the back of Shuttle

Keep in mind that when voltage goes down, amperage goes up. All wire that carries 12V DC has to be sized accordingly. For instance to supply 12 volts to the 1800W inverter used on the shuttle bus required that we run 2 ought feeder to the buses' alternator. Also be sure that the alternator is large enough to take the load without burning out. On our 1800W rig we were able to run four 4' 4 Bank Kinos.

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SL&G's custom 1800W BattVerter powers 16 - 4' Kino Flo single tubes rigged in the interior and on the exterior of an Airport Shuttle

If you need more than 1800Watts you have no alternative but to tow a small portable generator behind the bus. I would suggest a Honda EU6500is Inverter Generator with a transformer/distro. The Honda is so quiet that you will not notice it over the noise of the bus engine. When the bus is stationary, if you hear the generator at all, it will sound like the bus engine is idling. The Honda EU6500is inverter generator is much quieter than the older movie blimped Honda EX5500. Part of what makes the new Honda EU6500is so quiet is it’s “Eco-Throttle.” The Eco-Throttle’s microprocessor automatically adjusts the generator's engine speed to produce only the power needed for the applied load. It can do this because the Inverter Technology of the Honda EU6500is enables it to run at different RPMs and maintain a constant frequency and voltage. Where conventional generators like the Honda EX5500 and ES6500 have to run full speed at a constant 3600 RPM to produce stable 60 hertz (cycle) electricity, a Honda EU6500is only needs to run as fast as required to meet the load demand. Since their engines do not have to run at full speed, and the fact that an inverter generator generates 20% more power per revolution of the engine, makes the Honda EU series of inverter generators substantially quieter than conventional models.

To make them even quieter, Honda has designed a new separate triple chamber construction and a new centralized intake/exhaust system. The net result is that the EU6500is is half as loud (ten decibels) as the comparable EM7000is and ES6500 generators typically found at lighting rental houses. Honda's EU Series generators operate at 34 to 44 dBA at 50 ft. - well below what is required for trouble free location recording and quieter than your typical Crawford 1400 Amp “Movie Blimped” Generator. With sound specs this good all you need to record sound without picking up generator noise is a real distro system that will allow you to tow the generator behind.

There is a company here in Boston by the name of ScreenLight & Grip that builds a step-down transformer for 6500W generators that doubles as a distro box. Their transformer/distro steps down the enhanced 240V output of their modified Honda EU6500is to a single 120V/60Amp (7500 Watt) circuit that is capable of powering larger lights, or more smaller lights, than you can without it (see my post at on RedUser.Net for more details.) You might want to look into using their 60A transformer/distro because it will enable you to tow the generator behind, yet have a flexible distro system inside the bus. You would use heavy duty 250V twist-lock extension cable between the transformer/distro on on the bus and the generator on a small trailer. The single heavy-duty 250V twist-lock cable would eliminate multiple cable runs to the generator and give you plug in points conveniently located in the bus.

Their 60A Full Power Transformer/Distro is equipped with the industry standard 60A/120V GPC (Bates) receptacle so you will need additional 60A GPC extension cables, 60-to-60 Splitters, and fused 60A GPC-to-Edison Breakouts (snack boxes) to run power around the bus - breaking out to 20A Edison outlets at convenient points. The best part about their transformer/distro is that no matter where in the distribution system you plug in, the transformer/distro automatically balances the additional load, so that you don't have to. If you use it with their modified Honda EU6500is generator, you simply plug in lights until the load wattage displayed on the “iMonitor” of the generator control panel reaches 7500 Watts. An overload alarm on the “iMonitor” display will tell you if you inadvertently overload the 60A Transformer/Distro. It is so simple that you don’t need to be an experienced electrician to operate it.

If you don’t want to tie marine cells into the alternator of the bus, I would highly recommend this new Gen-set system. I have used it on several Red shoots. The generator is super quiet. The transformer/distro gives you access to more power (7500 Watts continuous) and greatly simplifies your set electrics. For example, as I mentioned on my Red User post, I used one recently to power a lighting package that consisted of a 2.5kw, 1200, & 800 HMI Pars, a couple of Kino Flo ParaBeam 400s, a couple of ParaBeam 200s, and a Flat Head 80. Given the light sensitivity of the Red Camera, this was all the light we needed to light a large night exterior. Use this link for more information about using transformers on portable gas generators:

- Eileen Ryan, Boston Gaffer
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#8 Guy Holt

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Posted 09 November 2009 - 06:29 PM

Another alternative to rigging a generator outside the bus is a Battery/Inverter set up that is commonly called a "Battverter." A "Battverter" system consists of a deep cycle 12V DC power source (usually Marine Cells), a 12V DC-to– 120V AC True Sine Wave Power Inverter, and a Battery Charger. Battverters can work great for traveling car shots but offer limited capacity and run time.


If you will recall Eileen we had an unusually high neutral return on that inverter rig because of the harmonics that the Kino T-12 ballasts were dumping back into the power stream. If I were to do it again, I would do it differently. But, first in the interest of full disclosure, I should say at this point that in addition to being a gaffer, I own and operate ScreenLight & Grip – the rental house Eileen mentions that rents and sells the equipment she recommends above. If what I am about to say sounds like I’m hyping the Kino Flo product line it is not because we rent and sell them. We are dealers and rental agents for just about all the major brands. As a professional Gaffer of a lot of tight budgeted historical documentaries for PBS’ American Experience and The History Channel (see my “credit-entials” on Imbd), I think it is worth noting that the Kino Flo Parabeam fixtures are a viable alternative to HMIs when used with the new inverter generators because they offer low budget independent filmmakers a more affordable alternative to HMI lighting.

My recommendations are based upon extensive research I have done on the use of portable gas generators in motion picture production. For this research, I ran a series of tests in order to analyze the interaction of conventional AVR generators (a Honda EX5500 with Crystal Governor), as well as inverter generators (a Honda EU6500is), with the prevalent light sources available today. I have compiled the results of my tests in an article for my company newsletter and it is available on our website.

If I were to light that shuttle bus again, I would only use the Kino T-12 tubes where I absolutely had to because they were serving as practical lights in the shot. For off-camera lights I would instead use Parabeam or Diva lights because their ballasts are Power Factor Corrected and don’t dump harmonic currents into the power stream the way the T-12 ballasts do. If the power is being supplied by a small portable generator, I would strongly recommend they use a inverter generator and as many Kinos with PFC ballasts as possible. With a Power Factor Rating of over .9, the Parabeam and Diva fixtures are especially well suited for use on small portable generators.

In situations like this, the drawback to the older style Kino Flo fixtures that use the T-12 tubes (the Single, Double, and 4 Bank Fixtures, the Wall-o-Lite, Flathead 80, and the Image 20, 40, & 80 fixtures) is that their ballasts are not Power Factor Corrected and so return harmonic currents into the power stream. When used in quantity, as in studio chroma key productions, they can constitute a source of considerable harmonic noise in the power stream. For this reason, Kino Flo cautions users, on their website: “Kino Flo ballasts are generally not power factor corrected. They will draw double the current on the neutral from what is being drawn on the two hot legs. On large installations it may be necessary to double your neutral run so as not to exceed your cable capacity.”( FAQ “Why is the neutral drawing more than the hot leg” at http://www.kinoflo.com/FYI/FAQs.htm#2) For a detailed explanation for why harmonic currents cause unusually high neutral returns see my article on the use of portable generators in motion picture production available on our website.

When you plug a single 4’ - 4 Bank Kino into a wall outlet you need not be concerned about harmonic currents. As is the case with non-PFC HMI ballasts discussed elsewhere in this this forum, the impedance of the electrical path from the power plant is so low, the distortion of the original voltage waveform so small (1-3%), and the plant capacity so large in comparison to the load of the one light, that the inherently noisy load of the 4’- 4 Bank Kino will not affect the voltage at the distribution bus.

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Left: Grid Power w/ no load and a THD of less then 3%. Center: Conventional Generator w/ no load and a THD of 17-19%. Right: Inverter Generator w/ no load and a THD of 2.5%.


It is, however, an all together different situation when plugging Kino Flo T-12 fixtures into conventional portable generators. As a comparison of the oscilloscope shots from my article above and below indicate, the return of harmonic currents by conventional Kino Flo T-12 ballasts can generate voltage distortion in the power stream. Given the large sub-transient impedance of conventional portable generators, and the fact that the original supply voltage waveform of conventional generators is appreciably distorted (a THD of 17-19%) to begin with , you have a situation where the return of any harmonic currents by a non-PFC electronic ballast (HMI or Kino) will result in significant waveform distortion of the voltage in the distribution system.

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Left: Grid Power w/ Kino Flo Wall-o-Lite. Center: Conventional AVR Power w/ Kino Flo Wall-o-Lite. Right: Inverter Power w/ Kino Flo Wall-o-Lite.


Given the effect of just one 10–tube Kino Flo Wall-o-Lite with non-pfc electronic ballasts on a 5500W conventional generators, what would be the accumulative effect of a typical lighting load on a generator? To see, I ran a package consisting of two Arri 1200 HMI Par Pluses with standard Arri non-PFC electronic ballasts in addition to the Kino Flo Wall-o-Lite on the Honda EX5500 (a conventional generator). And, for the sake of comparison, I ran the same package but with power factor corrected electronic ballasts on our modified EU6500is (an inverter generator.) The difference between the resulting waveforms below is startling.

The adverse effects of the severe harmonic noise exhibited below left, can take the form of overheating and failing equipment, efficiency losses, circuit breaker trips, excessive current on the neutral return, and instability of the generator’s voltage and frequency. For these reasons it has never been possible to reliably operate more than a couple of 1200W HMIs on a conventional 6500W portable gas generator. Harmonic noise of this magnitude can also damage HD digital cinema production equipment, create ground loops, and possibly create radio frequency (RF) interference. For a detailed explanation for why this is, see my article on the use of portable generators in motion picture production available on our website.

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Left: Conventional generator power w/ pkg. of non-PFC Elec. HMI Ballasts & Kino Flo Wall-o-Lite. Center: Scope time base adjusted to bring elongated waveform back on screen. Right: Inverter generator power w/ Pkg. of PFC Elec. Ballasts & Kino Flo Parabeam 400.


Why are harmonics suddenly an issue in motion picture electrical distribution systems? First, one must appreciate that the power generation and electrical distribution systems developed for motion picture production were never designed to deal with an abundance of non-linear loads like electronic HMI and Kino Flo ballasts. It’s a problem that has only recently begun because of the increasing use of these types of non-linear lighting loads. The problem is being further compounded by the increasing prevalence on set of sophisticated electronic production equipment like computers, hard drives and HD monitors which are themselves sources of harmonic distortion. The increasing use of these microprocessor-based equipment in production has created an unprecedented demand for clean, reliable power on set at a time when the prevailing light sources are dumping more and more noise into the power stream.?

It is worth noting in the oscilloscope shots above that the distortion of the voltage waveform is considerably less in the case of our modified Honda EU6500is inverter generator (far right) with PFC ballasts than that of the conventional Honda EX5500 generator with non-PFC ballasts (left.) The reason for this is that, as discussed at length in my article, the original waveform of the power generated by the EU6500is (an inverter generator) has less harmonic distortion at the outset than that originally generated by a EX5500 (conventional generator.) For this reason, when your lighting package consists predominantly of non-linear light sources, like HMI and Fluorescent lights, it is important to have power factor correction (PFC) circuitry in the ballasts (HMI & Kino) and operate them on inverter generators like our modified Honda EU6500is. The combination of improved power factor and the nearly pure power waveform of inverter generators makes it possible to power larger lights, or more smaller lights, than has been possible before on a small portable gas generator.

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Wide Shot of Night exterior scene lit with our HD P&P Pkg.


For example, the substantial reduction in line noise that results from using power factor corrected Kino and HMI ballasts on the nearly pure power waveform of an inverter generator creates a new math when it comes to calculating the load you can put on a generator. In the past we had to de-rate portable gas generators because of the inherent short comings of conventional generators with AVR and Frequency governing systems when dealing with the harmonic noise of non-PFC electronic ballasts. The harmonic distortion created by non-PFC ballasts reacting poorly with the distorted power waveform of conventional AVR generators (as evident in the oscilloscope shots above) limited the number HMIs and Kinos you could power on a portable generator to 60% of their rated capacity (4200Watts on a 6500W Generator).

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Two Shot of Night exterior scene lit with our HD P&P Pkg


But now, that inverter generators have virtually no inherent harmonic distortion or sub-transient impedance and power factor correction (PFC) is available in both small HMI and Kino Flo Parabeam ballasts, this conventional wisdom regarding portable gas generators no longer holds true. Where before you could not operate more than a couple 1200W HMIs with non-PFC ballasts on a conventional generator because of the consequent harmonic distortion, now according to the new math of low line noise, you can load an inverter generator to capacity. And if the generator is our modified EU6500is inverter generator, you will be able to run a continuous load of up to 7500W as long as your HMI and Kino ballasts are Power Factor Corrected.

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The PFC 2.5 & 1.2 HMI Pars, PFC 800w Joker HMI, Kino Flo Flat Head 80, 2 ParaBeam 400s, and a ParaBeam 200 of our HD P&P Pkg. powered by our modified Honda EU6500is through our 60A Full Power Transformer/Distro


Another, benefit to having PFC circuitry in the Parabeam and Diva ballasts is that they use less power. That’s because this advanced electronics contributes to a more economical use of power in the Parabeam and Diva ballasts than Kino Flo’s conventional ballasts. For example, the Parabeam 400s and Diva 400s draw less than half of the power (2 Amps) than the 4’ – 4 Bank Kinos that we used (4.6 Amps). While this nearly 3 amp difference is not a major consideration when using house power, in situation like this (when your power is coming from a portable generator) it can make a difference because you can use two Parabeam 400s for the same power as a 4’ – 4 Bank Kino.

When you add up the incremental savings in power to be gained by using only PFC ballasts, and combine it with the pure waveform of inverter generators, you can run more lights on a portable gas generator than has been possible before. For example, on a recent Red shoot (see production stills above and below) the 7500W capacity of our modified Honda EU6500is Inverter Generator powered a lighting package that consisted of a PFC 2.5kw HMI Par, PFC 1200, & 800 HMI Pars, a couple of Kino Flo ParaBeam 400s, a couple of ParaBeam 200s, and a Flat Head 80. Given the light sensitivity of HD cameras, this is all the light needed to light even a large night exterior. (For more details on how this is accomplished I suggest you read my newsletter article on the use of portable generators in motion picture production. The article is available on our website.

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A Distro System consisting of a 60A Full Power Transformer/Distro, 2-60A GPC (Bates) Splitters, 2-60A Woodhead Box distributes power from a modified Honda EU6500is. Even though the generator is 100' away to reduce noise, plug-in points remain conveniently close to set.


Given how well Kino Flo Parabeam ballasts interact with inverter generators, not to mention their versatility (they can operate both 5500K & 3200K lamps) and their efficiency (they consume 1/10 the power of comparable incandescent soft lights), Kino Flo Parabeam lights would appear to be the better source for this type of rig.

Guy Holt, Gaffer, ScreenLight & Grip, Boston
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#9 Eileen Ryan

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Posted 09 November 2009 - 07:43 PM

If you will recall Eileen we had an unusually high neutral return on that inverter rig because of the harmonics that the Kino T-12 ballasts were dumping back into the power stream.


Yes, I do remember the neutral getting very warm. Then we doubled the size of it and didn't have a problem after that. I never would have thought powering just four Kino 4'-4 Banks would be such a challange.

Eileen Ryan, Gaffer, Boston
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