Fluorescent as key light.

[KREEDMAN]

I am trying to buy a set of Fluorescent lights and I am aware of it being weaker than Tungsten. What light kit do you recommend for flood and key light, how much illumination can I get from Fluorescent?

I know that I would like to start at 2K if I'm buying Tungesten, what can i find equivelent in Fluorescent?

Thanks!

 

[Huy Vu]

Well you don't really want to start with 2k tungsten unless you only want one light lol. Household circuit usually maxes out at 20 amps which is enough to run a single 2k light. And it's not true that fluorescents are "weaker" than tungsten, that's a common misconception. If anything flos are stronger because they put out 4x as much light while drawing 4x less power. What it is is that flo have less throw, meaning that their light output weakens much more quickly over longer distance compared to a hard source. So it is not a question of wattage, but of distance. If you will be lighting a wide shot in a banquet hall for instance, you probably don't want to use flo. When placed at an appropriate distance however, flo are more than capable of acting as a key. 200w and 400w(ish) are commonly used, about equivalent to 500w and 800w tungsten respectively. More than enough for most things if the situation is right. Fluorescents are not general purpose lights.

 

[KREEDMAN]

hmmm....so I should be asking what should I get for a long throw?

What you said makes sense! thanks.

 

[nejuicer]

hmmm....so I should be asking what should I get for a long throw.

Conventional fluorescent movie lights don’t make good key sources for dramatic scenes because they have a very broad light output that is hard to control. These lights also tend to drop off rapidly which means that to serve as a Key source, the units need to be positioned close to the subject they are lighting. These characteristics make them best suited to serve as Key sources in documentary interview set-ups where the Keys are typically positioned close to the interview subject. In that capacity conventional fluorescent lights can generate a wonderful soft light that wraps around the interview subject without wilting them. But, given these characteristics, conventional fluorescent movie lights have only limited applications as fill sources in dramatic set lighting.

The one exception is the Kino Flo Parabeam lights. The Parabeam lights incorporate features that make them a much better key source than any other fluorescent light. 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. 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 have features that make them a better key source than just about any other fluorescent light.

If you are lighting a movie, you will be better served by a ParaBeam 400 fixture than other fluorescent light because they use computer aided designed (CAD) parabolic reflectors to focus their light output where it is needed most for lighting dramatic scenes - at a medium distance – making it a better key source. If you compare the photometric tables of the Parabeam 400 with those of a Kino Flo Diva 400 (which uses the same four lamps), you will notice that at 16’ the Parabeam 400 puts out almost three times the light level (28FC) than the Diva 400 (10FC) even though they both use the same tubes. In fact a Parabeam 400 generates as much light at 16’ as the 4’ 8-Tube Kino Flathead 80 fixture, yet uses less than a quarter of the power – making it an ideal light to operate on a portable generator.

Not only do the Parabeam fixtures have more throw than other fluorescent lights but they are also more easily controlled – an essential requirement in a key source. Parabeam fixtures are controlled by interchanging Kino Flos’ innovative Honeycomb Louvers. Louvers are available in 90, 60 and 45 degrees. Swapping louvers provides beam control similar to that of swapping lenses on an HMI Par. These features enhance the production capabilities of the Parabeam fixtures and make them suitable to serve as a key or backlight source where conventional fluorescent fixtures will spill all over a set and are therefore only suited to serve as fill sources.

Since, many dramatic scenes take place outdoors at night, how well a fluorescent light operates on portable generators is another consideration one should take into account. Unlike most conventional fluorescent movie lights, the Parabeam fixtures use ballasts that include Power Factor Correction (PFC) circuitry. As it does in HMI ballasts, this advanced electronics contributes to a more economical use of power than conventional electronic ballasts. For example, a Kino Flo Parabeam 400 draws less than half of the power (2 Amps) of a 4’ – 4 Bank (4.6 Amps). While this nearly 3 amp difference is not a major consideration when using house power, it can make a difference when your power is coming from a portable generator because you can use two Parabeam 400s for the same power as a 4’ – 4 Bank.

The greater Apparent Power of conventional fluorescent lights is not the only consideration when choosing fluorescents for dramatic set lighting. When you use lights sources like HMIs, Kinos, CLF lamp banks, and even LEDs, on generators it matters what type of ballasts the light uses. The Harmonic Noise that ballasts with poor Power Factor kick back into the power stream can have a severe adverse effect on the power waveform of some generators. There is a video on You-Tube by a Lighting Designer by the name of Kevan Shaw that illustrates just this.

In his You-Tube Video, “Compact Fluorescent verses the generator,” (available at http://www.youtube.com/watch?v=LeCqreRMzKM) Kevan Shaw compares the effect of equal wattages of CFLs and Incandescent lights on a small portable generator. In his test, he first operates a 575W ETC Source Four Leko with Quartz Halogen bulb on an 850W two stroke conventional gas generator without problem. However, when he tries to operate an equivalent wattage of CFLs (30-18W bulbs) the generator goes berserk. Only after turning off half the CFL Bulbs does the generator operate normally with a remaining load of 15 - 18W CFLs (270 W.) What accounts for the erratic behavior of the generator in this video under a smaller load of CFLs? It is a combination of the poor Power Factor of the CFL bulbs and the harmonic currents they generate.

Even though the 15 CFL bulbs have a True Power of 270W (15 x 18W = 270W ), the Watt indicator on Kevan's generator indicates that they draw twice that in Apparent Power (535W), or have a Power Factor of .5 (270W/535W =.504.) The fact that CFL bulbs consume double the energy (Apparent Power) for the 18 Watts of light (True Power) they generate, is only half the story here. Kevan Shaw’s video also clearly demonstrates the severe effect that loads - like CFLs, HMIs, Kinos, & LEDS - with leading power factor can have on the governing systems of conventional AVR generators.

When Kevan turns off the 18W CFL bulbs one at a time until the generator stabilizes, he is not only demonstrating that 15 – 18W CFL bulbs has roughly the same Apparent Power (535W), according to the generator’s Watt meter, as a 575W incandescent light; but, also that the maximum Leading Power Factor load a 850W conventional generator can operate satisfactorily is 270 Watts (15 – 18W CFL bulbs). Looked at from another angle, 576 Watts of Apparent Power with a Leading Power Factor (16 - 18W CFL bulbs) overloaded the generator, while 575 Watts of Apparent Power with a Unity Power Factor (the 575W Quartz Leko) did not. What accounts for this difference? Since the load is almost the same (576 & 575 Watts of Apparent Power respectively), the only factor that can account for the generator going berserk with the equivalent load of CFL lights is the harmonic currents that they generate, that the Quartz Leko does not. Without a doubt, Kevan Shaw’s video is a clear demonstration of the adverse effect that harmonic currents have on the governing systems of conventional AVR generators. Where I am out of space on this post, I will pick up with another why the Kino Flo Parabeam is better for generator operation than most flourescnet movie lights.

- Guy Holt, Gaffer, ScreenLight & Grip, Lighting and Grip Rental in Boston

 

[nejuicer]

I will pick up with another why the Kino Flo Parabeam is better for generator operation than most flourescnet movie lights.

In the studio applications for which most fluorescent lights are designed to be used, harmonic currents are less of a concern than they are in location production applications. Put simply, when you plug a fluorescent light into a wall outlet you need not be concerned about harmonic currents. As is the case with non-PFC HMI ballasts 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 a standard fluorescent light will not affect the voltage at the distribution bus.

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%.​

As is evident in the oscilloscope shots below, it is an all together different situation when plugging the same fixture into conventional portable generators. The non-pfc ballasts of the older style Kino fixtures that use T-12 ballasts (the Single, Double, & 4 Bank Fixtures, the Wall-o-Lite fixture, as well as the Image 20, 40, & 80 fixtures return harmonic currents into the power stream that can generate voltage distortion. 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, whether by a non-PFC electronic ballast (HMI or Kino), results in significant waveform distortion of the voltage in the distribution system. The generation of harmonic currents by production equipment should be eliminated whenever possible, otherwise, as we saw in Kevan Shaw’s video, it can build to a point where it will have an adverse effect upon not only the generator but also on other equipment running on the same power.

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.​

For example, for an article I wrote for our company newsletter on the use of portable generators in motion picture production, I ran a package consisting of two Arri 1200 HMI Par Pluses (with standard Arri non-PFC electronic ballasts) in addition to a 4’ – 10 tube Kino Flo Wall-o-Lite (with T-12 Ballasts) on a Honda EX5500 (a conventional generator). And, for the sake of comparison, I ran a comparable package but with power factor corrected electronic ballasts on our modified 7500W EU6500is (an inverter generator.) The difference between the resulting waveforms was startling.

The adverse effects of the severe harmonic noise generated by non-pfc light fixtures (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 along with non-pfc Fluorescents on conventional portable gas generators. Harmonic noise of this magnitude can also damage HD digital cinema production equipment, create ground loops, and create radio frequency (RF) interference. For a detailed explanation for why this is, see my article which is available on our website.

Left: Conventional generator power w/ pkg. of non-PFC Elec. HMI Ballasts & Kino Flo Wall-o-Lite. Right: Inverter generator power w/ Pkg. of PFC Elec. Ballasts & Kino Flo Parabeam 400.​

It is worth noting in the oscilloscope shots above that the distortion of the voltage waveform is considerably less in the case of the inverter Honda EU6500is generator (far right) than that of the conventional Honda EX5500 generator (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 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.

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 PFC 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 HMI and Fluorescent fixtures. The harmonic distortion created by their 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 Fluorescents you could power on a portable generator to 60% of their rated capacity (4200Watts on a 6500W Generator).

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​

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 the Kino Flo Biax fixtures, 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 HMIs and Kinos are Power Factor Corrected.

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.​

According to this new math, when you add up the incremental savings in power to be gained by using only PFC Lights, 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, the 7500W capacity of our modified Honda EU6500is Inverter Generator powered a lighting package for a recent Red shoot (see production stills above) 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.

If you haven't already, I would suggest you read the article I wrote for our company newsletter on the use of portable generators in motion picture lighting. In it I cover some of the basic electrical engineering principles behind harmonic distortion and how it can adversely affect generators. Harry Box, author of “The Set Lighting Technician’s Handbook” has cited my article in the just released Fourth Edition of the handbook. In addition, he has established a link to it from the companion website for the Fourth Edition of the Handbook, called “Box Book Extras.”

If you haven't yet read the article, or looked at it in a while, it is worth reading. I have greatly expanded it to be the definitive resource on portable power generation for motion picture production. Of the article Harry Box states:

"Great work!... this is the kind of thing I think very few technician's ever get to see, and as a result many people have absolutely no idea why things stop working."

"Following the prescriptions contained in this article enables the operation of bigger lights, or more smaller lights, on portable generators than has ever been possible before."​

The “Box Book Extras,” site is also worth checking out because it includes other source material used for the handbook, articles by Harry Box published in other periodicals, related websites, a list of production oriented i-phone apps, as well as more in depth discussion of topics touched upon in the handbook. You can log onto the Box Book Extras site at http://booksite.focalpress.com/box/setlighting/ with our pass-code "setlighting." Use this link for my news letter article on the use of portable gas generators in motion picture production.

Guy Holt, Gaffer, SceenLight & Grip, Lighting and Grip Rental in Boston.