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Film School Dumping Kinos for LEDs


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#1 Camilo Moncada

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Posted 29 March 2011 - 12:25 AM

Hi Everyone,

I just heard a rumor that my school (A very prestigious film school in Mexico City wich shall remain unnamed) is tossing away all Kinoflos and goinig for LEDs instead. The argument they gave us was that LEDs outperform Kinos in terms of output, power consumption, flicker issues... oh and price.

I´m aware of the practical and budgetary advantages of LEDs but I´m not sure getting rid of Kinos altogether is the wisest thing to do.

Could someone please help me make the case for Kinos so that we can argue with the school authorities to keep this valuable tool in our meager arsenal.

Thanks!
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#2 John Sprung

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Posted 29 March 2011 - 12:45 AM

If they're literally tossing them, it's time for a dumpster dive.... ;-)





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#3 Camilo Moncada

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Posted 29 March 2011 - 01:09 AM

Well, the few Kino units they have are a few yars old and most of them just don´t work propperly, so they won´t buy new ones or repair the ones they have ;they´ll just replace them with LEDs.
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#4 Ronald Gerald Smith

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Posted 29 March 2011 - 03:13 AM

John, I am right there with you in the dumpster. Beat you to it!

Personally, I prefer the flexibility of Kinos...

Edited by Ronald Gerald Smith, 29 March 2011 - 03:14 AM.

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#5 Guy Holt

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Posted 29 March 2011 - 10:03 AM

Could someone please help me make the case for Kinos so that we can argue with the school authorities to keep this valuable tool in our meager arsenal.


Perhaps LEDs outperform the old style Kinos in terms of output and power consumption, but I would not say that is the case with the newer style Kinos like the Divas, Parabeams, BarFlys, and Vistabeams. While LED Lights are getter brighter, they are still not comparable to the newer Kino sources. In my opinion, LED lights are still only a special purpose tool and not suitable for general production. When they are used in production they are best used as Obie lights or to light car interiors at night. Like every other DP & Gaffer, I have put together my favorite lighting package based upon my more than 20 years operating a lighting rental, sales, and production service company. For my package, I have picked lights that I feel offer both the highest output (lumens/watt) and the best production capability and have combined them with distribution technology I've developed that enhances the production capability of the new Honda Inverter Generators. As yet, I have not found a LED lighting fixture that warrants inclusion in my package. Trust me, I have looked at all of them and some still to come. Here are a few of my reasons why I prefer the newer Kino lights, especially the Kino Flo Parabeam fixtures, over LED Panels for many of the applications that LEDs are being marketed for and it has to do with more than just the poor CRI of LEDs (the results of the Academy of Motion Picture Arts and Sciences’ “Solid State Lighting Project Technical Assessment available at http://www.oscars.or...hnicalinfo.html are reason enough to avoid LEDs for now.)

In HD Digital Cinema, the quality of light is more critical than ever. In High Def every detail of “on-camera” talent is rendered clearly on the screen – even the imperfections. Where LED and traditional hard light sources can exaggerate textural details, it is my opinion that fluorescent soft light is better for lighting talent in High Def productions because it can subdue those same textures and render a more cosmetic appearance. Primarily for this reason, I prefer the Kino Flo fixtures, over LED Panels, to serve as a Key source. For dramatic productions (non-interview), I especially like the Kino Flo Parabeam fixture because they offer a number of advantages over LEDs and even other Kino fixtures.

What distinguishes the Parabeam fixtures from LED Panels and other fluorescent lights is their throw, power efficiency, and the innovative accessories Kino Flo makes available for the fixtures. Accessories include barndoors, a gel frame, a diffusion panel, and Honeycomb Louvers. These features enhance the production capabilities of the Parabeam fixtures and make them suitable to serve as a key, or even backlight source, where conventional fluorescent movie lights and LED light panels are not.

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


Both conventional fluorescent movie lights (Kino Flo’s included) and LED light panels 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 and LED light panels (with heavy diffusion) can generate a wonderful soft light that wraps around the interview subject without wilting them. But, given these characteristics, conventional fluorescent movie lights and LED light panels have only limited applications as fill sources in dramatic set lighting.

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Wide Shot of Night exterior scene lit with a pkg. consisting of PFC 2.5 & 1.2 HMI Pars, PFC 800w Joker HMI, Kino Flo Flat Head 80, 2 ParaBeam 400s, and a ParaBeam 200 powered by a modified Honda EU6500is.


The ParaBeam fixtures, on the other hand, have computer aided designed (CAD) parabolic reflectors that focus their light output where it is needed most for lighting dramatic scenes - at a medium distance – making them better suited as a Key source for HD Digital Cinema. If you compare the photometric tables of the Parabeam 400 and the 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. You can always diffuse a Parabeam to create a soft source, but nothing you do will make a Diva 400 or LED light panel punchier.

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Note Distance at which the two ParaBeam 400s are serving as Keys.


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 (2 Amps verses 9.2 Amps.) While the seven amp difference is not a major consideration when using house power, it can make a difference when your power is limited (coming from a portable generator) because you can use four Parabeam 400s for the same power as a 4’ – 8 Bank Kino Flathead 80. And unlike the ballasts of Kino Flo’s fixture that use the T12 tubes, the Parabeam ballasts also include Power Factor Correction to reduce the return of harmonic currents into the power stream and improve their power efficiency. This makes them an especially efficient fluorescent light source that is comparable to the power efficiency of LED light panels, but without the harmonic noise that LED Light panels generate (see below for details.) For instance a Parabeam 400 puts out considerably more light than even Zylight’s new high output LED light panel yet draws just .2 Amps more power.

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Voltage and Current waveforms generated by SMPS type AC-to-DC Converter used to drive AC LEDs.


By comparison, the Switch Mode Power Supplies (SMPSs) used to operate LEDs on AC draw a very distorted current, and can result in current that is significantly phase-shifted with respect to the sinusoidal voltage waveform. Although values vary widely, the SMPSs used in AC LEDs generally have a Leading Power Factor and high harmonic distortion (THD upwards of 68.1%). Power Factors for AC LEDs range from 0.54 (Litepanel 1x1s), to 0.85 (Litepanel Sola Fresnels). As such, High Power LEDs can have an adverse effect on power quality similar to that of CFL bulbs. (Use this link - http://www.screenlig...generators.html - for a detailed description of the adverse effects that LEDs can have on portable generators.)


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Distribution of harmonics generated by the power supply of the Litepanel 1x1 LED Fixtures. Note: predominance of the 3rd, 5th,
7th, and 9th harmonics that don't cancel on neutral returns.


While the newest LED light panels (that use the higher output LEDs) approach the Parabeams in output, the Parabeam fixtures are 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 movie lights and LED light panels will spill all over the set.

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The type of voltage waveform distortion that can be generated in conventional AVR generators by SMPS type AC-to-DC Converter used to drive AC LEDs.


The power that I save by using Parabeam 400s for key sources in my package, enables me to power more lights on the enhanced 7500W output of my modified Honda EU6500is generator. Using a 60A Full Power Transformer/Distro on my modified Honda EU6500is I am able to power a lighting package that consists of a 2.5kw, 1200, & 800 HMI Pars, a couple of Parabeam 400s and Parabeam 200s, and a Flat Head 80. Given the light sensitivity of the HD cameras these days, this is all the light you need to light a large night exterior.

Compared to LED fixtures, Kino Flo Parabeam fixtures are as power efficient, generate less Harmonic Noise, offer greater versatility and output. Able to interchange different color temperature tubes, and vary beam spread with their interchangeable honeycomb louvers, the Parabeam fixture can do what it takes four different LED Litepanel fixtures to accomplish – Spot and Flood in both 5500K and 3200K. Offering better light quality, output, beam control, and versatility, the Kino Flo ParaBeams make for a better key or back light for HD cinema production. I would suggest that your school look at buying the next latest generation of Kinos, and wait until LED technology matures before buying into it.

I would suggest you have your teachers 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 the poor Power Factor of LED power supplies, the harmonic distortion they can generate, and how it can adversely affect generators.

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This article is cited in the just released 4th Edition of Harry Box's "Set Lighting Technician's Handbook" and featured on the companion website "Box Book Extras." Of the article Harry Box exclaims:

"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 article is available online at http://www.screenlig...generators.html.

Guy Holt, Gaffer, ScreenLight & Grip, Lightng & Grip Rental & Sales in Boston
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#6 Phil Rhodes

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Posted 29 March 2011 - 12:02 PM

You are of course aware that an LED driver doesn't have to be like that.

The problem I see with current LED designs is that they'll slowly (or perhaps not so slowly) lean toward purplish-blue as they age. Only the most recent and high-tech versions have sufficient technology to counteract this.

I'm not so sure I see the issue with throw. In my experience LEDs are punchy, throwing a soft light a long distance from the device itself, probably because a lot of LED devices are made of a large array of discretes each with collimating optics. A fluorescent tube is, by its nature, more of an omnidirectional glow.

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#7 John Sprung

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Posted 29 March 2011 - 12:33 PM

Well, the few Kino units they have are a few yars old and most of them just don´t work propperly, so they won´t buy new ones or repair the ones they have ;they´ll just replace them with LEDs.


If you can get them for free, or really cheap, do it. Figure out what's wrong, take parts from some to fix others, and learn about how they work. When you have them in hand, let us know.




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#8 Stuart Brereton

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Posted 29 March 2011 - 02:02 PM

Guy,

That is at least the fourth time you have posted the exact same article. I appreciate the information you are sharing, but perhaps you could just link to it in future, rather than subject us all to a lengthy infomercial
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#9 Guy Holt

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Posted 29 March 2011 - 04:09 PM

You are of course aware that an LED driver doesn't have to be like that.


To be precise, LEDs used in motion picture lighting require direct current (DC) be applied to their diodes. For this reason the LED drivers in the heads are designed to regulate a DC input (not an AC input.) To plug them into the wall, some type of AC-to-DC converter must be used. Because of their higher efficiency AC-to-DC Switch-mode Power Supplies (SMPSs) are almost universally used for this purpose. And, yes, the SMPSs used in the AC power supplies do not have to generate the harmonic noise that they do. The incorporation of Power Factor Circuitry (PFC) in the power supply can re-align voltage and current and eliminate the harmonic noise. But, putting PFC circuitry in the power supply also makes the supply more expensive which is why manufacturers have for the most part not included it.

Power quality will become less of an issue as LEDs become more powerful because any manufacturer that wants to sell in the EU market will have to meet their guidelines that any electronic device over 75W has to incorporate PFC circuitry. Litepanels has been able to use less expensive power supplies because their lamp heads (including the Sola 6 “Fresnel”) are 75W or less and so are exempted from the EU guidelines that require Power Factor Correction. For instance, the AC power supply that Litepanels uses for their 1x1 panel arrays have a Leading Power Factor of 0.54 and generate high harmonic distortion (THD upwards of 68.1%).

After consulting with me about their new L-Series Fresnel, Arri is aware of the benefits to be derived from Power Factor Correction when it comes to operating LEDs on portable power generators (use this link for more details.) Since the LED Fresnel that they are releasing after NAB next month will be a 200W lamphead (with the output of a 1000W Fresnel) it will most certainly have to incorporate Power Factor Correction to meet EU guidelines.

I'm not so sure I see the issue with throw. In my experience LEDs are punchy, throwing a soft light a long distance from the device itself, probably because a lot of LED devices are made of a large array of discretes each with collimating optics. A fluorescent tube is, by its nature, more of an omnidirectional glow.


I have had the opportunity to do side-by-side comparisons with a number of LED panels and the Kino Parabeam 400 is considerably brighter. For instance a Parabeam 400 puts out more (98 FC at 8’) than even Litepanel’s 1x1 Super Spot fixture (64 FC at 8’) and with a larger field area.

The problem I see with current LED designs is that they'll slowly (or perhaps not so slowly) lean toward purplish-blue as they age. Only the most recent and high-tech versions have sufficient technology to counteract this.

In the L-series Fresnels, Arri is using color blending with a multi-emitter LED engine to overcome the generally poor color rendering capabilities of LED fixtures (use http://www.screenlig...Output AC LEDs' class='bbc_url' title='External link' rel='nofollow external'>this link to see how poor the color rendering capacity of LED fixtures has been.) In my conversation with Ryan Fletcher, the Arri LED product manager, they expect to achieve full spectrum 3200 and 5500 Kelvin color output with CRIs in the 90s. There is no reason to doubt that they can do it; after all Gekko has made great strides in that direction with their color tuneable ”Kleer Colour” multi-emitter LED light engine. The technology is out there, it's just a matter of finally bringing it all together in one fixture. To my mind, the Arri L-Series Fresnel may be that fixture, but we will have to wait until NAB to find out.

Guy Holt, Gaffer, ScreenLight & Grip, Lighting and Grip Rental & Sales in Boston
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#10 Guy Holt

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Posted 29 March 2011 - 04:16 PM

Guy, That is at least the fourth time you have posted the exact same article. I appreciate the information you are sharing, but perhaps you could just link to it in future, rather than subject us all to a lengthy infomercial


I may have posted some of the same information before regarding Parabeams, but I have not posted the “exact same article” before. The kid wanted reasons for his program not to dump Kinos, so I compiled a quick summary of the reasons why I prefer Kinos, especially the Parabeams, over LEDs from other posts. If you had read my newsletter article you would realize that while my post is long, it is a brief summary of the article and I did provide a link to the article in the post.

Yes, I have posted extensively on the harmonic noise generated by HMIs, Fluorescents, and now LED fixtures because it is a problem that is becoming more prevalent. By characterizing my posts as “lengthy infomercials”, you seem to imply that I am trying to sell an ignorant public a product they don’t need by scaremongering, when in fact I am only trying to raise an awareness of the adverse effect that an increase in harmonic noise as a result of a change in lighting technology (the introduction of Switch Mode Power Supplies (SMPS)), is having on set power. But, don't just take my word for it: apparently, harmonics generated by SMPSs is enough of a problem to warrant several sections in the fourth edition of the "Set Lighting Technician’s Handbook." To quote Harry Box (Page 385 under "Power Problems from Electronic Loads"):

"Much of today's lighting technology relies on electronics such as DC rectifiers (electronic HMI ballasts), tryristors (SCRs), and high-frequency switching power supplies (the IGBTs of electronic ballasts) with large capacitors on the front end. These loads can have undesirable effects on the current waveform, with associated ill effects such as overheating or failing equipment , efficiency losses, circuit breaker trips, excessive current on the neutral wire, interference and instability with generators, noisy or overheating transformers and service equipment, and even loosened electrical connections. In the following sections, we discuss the power factor and current harmonics and look at their effects. Your awareness of these effects will help you to intelligently test for problems and build systems that avoid or mitigate them. (the parenthesis are mine)"

Now does this sound like harmonics is not an increasing problem and I am just scaremongering? If at times it sounds like I am hyping the Kino Parabeams, it is not because we sell and rent them. Rather, it is because they are one of the few fluorescent lights out there that are power factor corrected and don’t generate harmonics. As a professional gaffer of numerous low budget historical documentaries for PBS, Discovery, TLC, and the History Channel, I also feel strongly that there are benefits to using them, rather than LEDs, on portable generators because of the low line noise they generate. And I think that is a persuasive argument that Camilo can use.

Guy Holt, Gaffer, ScreenLight & Grip, Lighting and Grip Rental & Sales in Boston
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#11 Phil Rhodes

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Posted 29 March 2011 - 08:46 PM

For instance a Parabeam 400 puts out more (98 FC at 8’) than even Litepanel’s 1x1 Super Spot fixture (64 FC at 8’) and with a larger field area




Yes, of course, but that wasn't really my point - LEDs produce a rather nice soft light, but it's projecting - it has longer range than a fluorescent of the same rating. Minor matter, perhaps.


Also - you think Arri really need your advice on PFC? It's not a black art.


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#12 Camilo Moncada

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Posted 29 March 2011 - 11:55 PM

Thank you all for your replies! It´s been quite an informative discussion.
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#13 Guy Holt

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Posted 30 March 2011 - 05:17 PM

... you think Arri really need your advice on PFC? It's not a black art.


Nice jab Phil. No, PFC is certainly not a black art. And, a company like Arri, certainly doesn't need my help with it. The black art that Arri was consulting me about is the marketing of LED fixtures. PFC is just one of many features that Arri could or could not incorporate into a new LED product line for the North American market. In our conversation, Ryan Fletcher, the LED product manager for Arri, said they were considering several AC-to-DC converters for the L-Series Fresnels and that they had not settled on whether it should incorporate Power Factor Correction (PFC) or not. Since it would add to the expense of a fixture, he wanted to know if I thought there would be enough benefit derived from it to offset the additional expense (remember this is the same company that only recently introduced PFC in 1200W HMI ballasts in this country.)

Without a doubt, their LED Fresnel line is going to be more costly per lumen than other light sources, and they realize that there has to be an additional benefit or savings to justify the additional expense for it to be successful in the market. They see that cost/benefit in the broadcast studio market because of the savings in power consumption (not only by the lights but also air-conditioning), lamp longevity (no need to replace burnouts), and gel longevity (no need to replace burned through gels.) In the Broadcast Studio market they feel these savings more than offset the additional expense of an LED Fresnel fixture. But, since PFC in not a necessity in that market, they wanted to hear from me if I thought that the reduced power consumption and line noise that would be the result of incorporating PFC in the product line for the North American Market (they have no choice for the EU market) was enough of a benefit to offset the additional expense in other markets.

What I told them was that for the regional commercial spot production market, direct to web marketing production market, independent short production market, and historical documentary production market there was more than enough benefit to be derived from incorporating PFC in a LED Fresnel fixture to offset the additional cost. The cost savings in these markets, I told them, comes in not having to rent a movie blimped tow generator with all of its’ hidden costs in order to obtain the production values required by these markets. Until recently, to power HMI lights over 1.2kw or Quartz lights over 2kw required a large diesel movie generator. Movie generators are not only expensive to rent, but they come with hidden costs that usually break the budget of modest HD projects like these. Movie generators require special tow equipment not found on Ryder or Penske rental trucks. For that reason, movie generators require that you rent a more expensive grip truck from a lighting and grip rental company in order to tow them. Lighting rental companies will not send out a grip truck without a company driver - further adding to the expense of renting a movie generator (in this market driver rates run about $500/10hrs with overtime after 10hr).

I told them that I felt that between the technological advances being made in HD cameras and in lighting design, when combined with advances we are making in portable power generation (the ability to power larger lights, as well as more smaller lights, off of portable Honda Inverter Generators), will change the way productions are lit in these segments of the production market. But, Power Factor Correction is integral and they should not make the mistake with LED Fresnels that they made with HMIs.
The primary factors limiting the use of HMIs on portable Honda generators in the past was their inefficient use of power and the harmonic noise they throw back into the power stream. For instance, the power waveform below left is typical of what results from the operation of a couple of 1200W HMIs with non-Power Factor Corrected ballasts on a conventional portable generator. The adverse effects of the harmonic noise exhibited here, can take the form of overheating and failing equipment, efficiency losses, circuit breaker trips, excessive current on the neutral wire, and instability of the generator’s voltage and frequency. For these reasons it has never been possible to 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. And, since the increasing use of personal computers, hard drives, and microprocessor-controlled recording equipment in production has created an unprecedented demand for clean, reliable power on set, it is critically important that all lights have power factor correction incorporated into them when the power is coming from a putt-putt generator.

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Left: Distorted power waveform created by Non-PFC 1200W HMI ballasts on conventional generator. 
Right: Near perfect power waveform created by the same lights with PFC ballasts on inverter generator.

By comparison, using only Power Factor Corrected lights on inverter generators
 creates clean stable set power that is capable of operating larger lights (HMIs up to 6kw or Quartz lights up to 5kw), or more smaller lights, off of portable gas generators than has ever been possible before. For example, the power waveform above on the right, is the same package of HMI lights but with power factor corrected electronic HMI ballasts operating on our modified Honda EU6500is Inverter Generator. As you can see, the difference between the resulting waveforms is startling. Even though we are running the same overall load, the fact that the HMI ballasts are power factor corrected and the power is being generated by our modified Honda EU6500is Inverter Generator, results in virtually no power waveform distortion. For this reason, sensitive electronic production equipment will operate reliably and without
damage. And, the generator is capable of operating larger, or more smaller, lights than has ever been possible before on a portable gas generator.

This is what the product developers at Arri were interested in learning about and what has Harry Box so pumped about our HD Plug & Play Gen-set and why he has included it in the 4th Edition of his Handbook. For example, the enhanced 7500W output of our modified Honda EU6500is Inverter Generator with our 60A Full Power Transformer/Distro is capable of powering a package consisting of a 2.5kw, 1800, & 400 HMI Pars, plus a couple of Kino Flo Parabeam 400s, Parabeam 200s, and a FlatHead 80 as long as all the ballasts were Power Factor Corrected. Given the light sensitivity of HD Digital SLRs and their new Alexa camera, this could constitute a complete location lighting package for modest HD productions like the commercial spots, direct web marketing videos, and public television historical documentaries mentioned above.

In our conversation, I encouraged the Arri product developers and marketing team to imagine what could be done with the addition of Power Factor Corrected LED Fresnels to this location package. Since they will use 75% less power than a Quartz fixture with comparable output, they will take what can be done with a portable generator like ours to the next level. I also strongly suggested that they speed up the planned introduction of the ARRIMAX reflector technology to the 4k HMI power class because a head with the output and light quality of a 12kw Fresnel that can operate on a portable Honda generator will take these productions to yet another level. Arri sought my input, not because I am some engineering wizard, but because they are very aware that, with the combination of camera systems like their Alexa (that are capable of a fourteen stop exposure range and ASA sensitivities of 1600 without grain) and with energy-efficient LED Fresnels and ARRIMAX reflector heads, you won’t need anything more than can be operated on the enhanced 7500W output of a Honda EU6500is in many production situations. What they wanted to know from me was whether the benefit to be gained by incorporating PFC in their new L-Series LED Fresnels would offset the additional cost in these situations.

In the end, I think, the Arri reps were convinced that the cost savings to be gained by eliminating not only the large tow generator, but also the added expense of a rental house grip truck, truck driver to tow it, and the extra electrical crew to distribute the power, are substantial enough to more than offset the additional cost of buying or renting a Power Factor Corrected LED Fresnel. That there are other markets beside news or corporate studio installations where the cost benefit of incorporating PFC circuitry in their new L-Series LED Fresnels works.

- Guy Holt, Gaffer, ScreenLight & Grip, Lighting and Grip Rental and Sales in Boston.
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#14 Phil Rhodes

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Posted 30 March 2011 - 05:59 PM

I certainly get the picture about the technicalities of PFC. What surprises me is that the cost difference to implement it made more than the slightest difference to the price of an Arri LED fresnel, which presumably costs one internal organ and your first-born child in the first place!

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#15 Guy Holt

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Posted 31 March 2011 - 10:07 AM

What surprises me is that the cost difference to implement it (PFC) made more than the slightest difference to the price of an Arri LED fresnel, which presumably costs one internal organ and your first-born child in the first place!


I don’t know the exact manufacturing cost to incorporating PFC circuitry in LEDs, but what I do know is that when Arri introduced the PFC option to their 575/1200 Electronic ballast is raised the price of the ballast by about $500.00. To get PFC in a 2.5/4kw ballast cost about $1000.00. Fred Horne, the former East Coast Sales Rep for Arri, once told me that they would have incorporated PFC as a standard feature in their 575/1200 and 2.5/4kw Electronic ballasts, but it wasn’t clear that the market would pay extra for it.

Apparently, incorporating PFC circuitry in LEDs is enough of a cost consideration to lead Litepanels to not incorporate it into their AC power supplies. Power Factors for their AC power supplies range from 0.54 (Litepanel 1x1s), to 0.85 (Litepanel Sola Fresnels), resulting in their having a Leading Power Factor and high harmonic distortion (THD upwards of 68.1% in the case of the 1x1s). Since Power Factor Correction (PFC) is not mandated in this country, as it is in Europe for any electrical device that draws more than 75W, LED manufacturers like Litepanels has not incorporated it into their power supplies. The same was true of electronic HMI ballasts when they first came out. They didn’t incorporate PFC as a standard feature unless it was absolutely necessary.

After a false start back in the 90s, all major manufacturers now include PFC circuitry in HMI ballasts in the 6-18kw range. They do so by necessity. The early line of Lightmaker electronic ballasts were nick named by film electricians “Troublemaker” ballasts because they were not Power Factor Corrected and proved that PFC circuitry was absolutely necessary in large ballasts to reduce heat and returns on the neutral, and to increase ballast reliability (beware, some are still kicking around rental houses). But, because of the added cost, weight, and complexity of PFC circuitry, ballast manufacturers in the US still offer PFC circuitry as an option in medium-sized ballasts (2.5-4kw). And, until very recently manufacturers did not offer PFC circuitry in HMI ballasts smaller than 2.5kw in the US.

Part of the reason for the number of non-PFC ballasts in this country was that PFC circuitry does not offer a huge advantage when operating HMIs on Crawford generators or tie-ins. A typical 4000W Power Factor Corrected electronic HMI ballast will draw 38 Amps at 120 Volts verses the 58 Amp draw of a non-PFC electronic ballast. Since neither ballast will operate on a standard 120V/20A wall outlet, PFC did not offer a huge advantage when operating 4k HMIs on Crawford generators or house power. However, the added efficiency of a PFC 4000W ballast can make a huge difference when powering a lighting package off of a portable generator. For example, when you consider that a Kino Flo Parabeam 400 draws only 2 amps, the 20 Amp difference between using a PFC 4000W electronic ballast and standard non-PFC 4000W electronic ballast, can mean the difference between running ten additional Parabeam 400s on a portable generator or not – I think you would have to agree that is a major boost in production capability and pertinent to any one using a portable generator as their principle source of set power.

The only power class below 6kw that Arri offers PFC circuitry as standard is their new EB1200/1800 electronic ballast for their new 1800W “Baby Max” head. But, again, it is because it is necessary if the new 1800W head is to operate on a 20A/120V circuit. It’s PFC circuit successfully increases its’ PF to .98, making it a near linear load. As a result, the ballast uses power more efficiently (so it can operate on a 20A circuit), minimizes return current and line noise, and also reduces heat, thereby increasing its’ reliability. The PFC circuitry of the new Arri EB1200/1800 also realigns voltage and current and and so it induces a smoother power waveform at the distribution bus of portable generators. Use this link for my news letter article on the use of portable gas generators in motion picture production. for more details about the benefits of using only PFC lights on portable generators.

In the final analysis, it is evident by these examples that PFC circuitry is enough of a cost consideration that Arri does not include it in a fixture unless it is absolutely necessary.

- Guy Holt, Gaffer, ScreenLight & Grip, Lighting and Grip Rental & Sales in Boston.
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#16 Phil Rhodes

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Posted 31 March 2011 - 10:32 AM

I guess that the Litepanels things just aren't a big enough load for it to make all that much difference, although if people are going to start using them in large arrays it might. The largest pack of the foot-square type I've seen was 16 units, which I guess is the best part of a kilowatt once you factor in inefficiency in the driver.

Do you happen to know what wattages Arri are going to build for the L series?


P
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#17 John Sprung

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Posted 31 March 2011 - 12:59 PM

Bottom line, with electronic ballasts, you can either pay more for the ballast and less for the generator, or less for the ballast and more for the generator. Doing the math both ways requires some assumptions that tip the balance.

How about a third option: Go to 24.000 fps instead of 23.976, and use magnetic ballasts. How do the power factor/price performance numbers work that way?





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#18 Phil Rhodes

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Posted 31 March 2011 - 01:25 PM

magnetic ballasts... power factor...



Not two phrases you want to see in the same sentence, at least as far as fluorescent tubes go! Inductors shift the current out of phase with the voltage, which is exactly what power factor is all about. Result: nothing nice.
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#19 Nathan Blair

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Posted 31 March 2011 - 03:12 PM

But, most of the time I see 1x1 LED litepanels running off interchangeable battery packs, as opposed to generators...
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#20 Guy Holt

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Posted 31 March 2011 - 03:18 PM

I guess that the Litepanels things just aren't a big enough load for it to make all that much difference


Your right. The poor Power Factor of an individual Litepanel 1x1 will not have a disastrous effect on a portable generator. And, I think, that is why it is not a high priority for manufacturers like Litepanels. However, poor Power Factor should be eliminated wherever possible because its’ accumulative effect can be severe. Light sources that use Switch Mode Power (HMI, Fluorescent, & LED) have almost entirely replaced incandescent lights as the prevalent lighting source in HD Digital Cinema production packages. To make matters worse, the video cameras, field monitors, hard-drives, lap-tops, and battery chargers that make up the typical location production package also use Switch Mode Power Supplies and hence generator their own harmonics. Where just about every piece of production equipment used on set today generates harmonics a viscous cycle can get started. The more harmonic orders that are generated, the more distorted the power supplied by the generator becomes. The more distorted the power waveform becomes, the more harmonic currents are thrown back into the electrical distribution system, which in turn, creates additional voltage distortion. In this fashion, something akin to a feedback loop can get started. Very often, the operation of electrical equipment may seem normal, but under a certain combination of conditions, the impact of harmonics is enhanced with unpredictable results.

… although if people are going to start using them in large arrays it might. The largest pack of the foot-square type I've seen was 16 units, which I guess is the best part of a kilowatt once you factor in inefficiency in the driver.


Exactly true. As more and more powerful LED fixtures come onto to market, they are going to be used in large arrays (like the ones pictured below) or in quantity on portable generators. The potential hazard comes when, because of the low wattage of the individual fixtures, users are lulled into complicacy. If the LED fixtures are not Power Factor Corrected, then their low wattage can create a dangerous sense of false security when it comes to sizing a portable generator for the lighting load.

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Besides the examples pictured here, take a hypothetical independent feature film shooting a night scene on a city street with a Canon DSLR. Because of the speed and light sensitivity of the camera and the amount of ambient light from store windows and street lamps they figure they can get away with a lighting package consisting of a 800W Joker Buglite to augment the background and four 40W 1x1 Litepanels to model their talent? It is a low budget production, so they can’t afford a grip truck but instead trick out a rental box. The rental box can’t tow a generator, so they plan instead to use a portable gas generator. Why not, after all they are using only energy efficient LEDs and a Joker 800? They opt for a conventional 1000W generator figuring it will be enough (800W+40W+40W+40W+40W = 960W). Will it work? No, because of the low wattage of the lights, they failed to consider their Power Factor when calculating the load that they will put on the generator and so they overload it. A careful analysis of the Power Factor of their lights (the Joker 800 and 1x1 Litepanels) indicates that their lighting package would in fact draw 1675W.

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Why? If we look at the technical specifications for the Joker 800 Buglite, we see that it uses a non-Power Factor Corrected ballast with a Power Factor of .58. According to the K5600 website, the Joker 800 ballast draws 12.5 Amps rather than the 7 Amps you would think using Ohm’s Law (800W/110V=7.2A.) What that means is that it has an Apparent Power of 1375W (110V x 12.5A = 1375W) or draws nearly twice the power to generate 800W of light output than a quartz instrument of the same wattage. Used on wall outlets, this relatively inefficient use of power is negligible because the power draw of the Joker 800 fits easily in a standard wall circuit. However, the greater Apparent Power of the Joker 800 must be factored when using portable generators because the generator must be sized to supply the Apparent Power (1375W), even though only the True Power (800W) provides light.

The same is true when it comes to the 1x1 Litepanels. According to the manufacturer, the AC-to-DC power supply that Litepanel uses for their 1x1 fixtures has a Power Factor of .54 and so draws nearly twice the power (an Apparent Power of 75W) for it’s true power output of 40W. If you were to use this lighting package on a 1000W conventional generator, the total Apparent Power of 1675W (1375W + 75W + 75W 75W + 75W = 1675W), would overload the generator. Even though it’s power is cleaner and more stable, you would not be able to run this package on a Honda EU1000is Inverter Generator either because, with a continuous load rating of 900W, the accumulative load of 1675W would also overload a 1000W inverter generator.

Could you operate this lighting package on a 2000W conventional generator? Again, the answer is “no” because the greater Apparent Power of lights with a poor Power Factor is not the only consideration when operating them on conventional generators. Of equal importance, is the Harmonic Noise that ballasts with poor Power Factor kick back into the power stream that severely limits the total amount of Leading Power Factor loads, as compared to Unity Power Factor loads, that can be reliably operated on conventional generators.

Given the large sub-transient impedance of conventional generators even a small degree of harmonic noise being fed back into the power stream will result in a large amount of distortion in its’ voltage. Add to that, the fact that the original supply voltage waveform of conventional generators is appreciably distorted to begin with, and you have a situation where the return of any harmonic currents by a non-PFC HMI, Fluorescent, or LED ballast will result in significant waveform distortion of the voltage at the power bus and operational problems with the generator voltage and frequency regulation. This is graphically illustrated in the You-Tube video, “Compact Fluorescent verses The Generator", by Lighting Designer Kevan Shaw’s (available on-line at href=", when he is not able to operate an equivalent Apparent Power of CFLs, as he could incandescent light, on his small 850W generator.

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In his You-Tube Video, “Compact Fluorescent verses the generator,” (available at ) 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.

For the same reason that Kevan Shaw was not able to operate more than 270 Watts of CFL bulbs (15–18W bulbs) on his little 850W generator, our hypothetical indie feature may not be able to operate their lighting package on a 2000W conventional AVR generator. After all CFLs have the same Power Factor as the Litepanel 1x1 power supplies (.54.) The adverse effects of the harmonic currents that non-PFC ballasts generate, so graphically demonstrated in Kevan’s video, limits the total amount of Leading Power Factor loads, as compared to Unity Power Factor loads, that can be reliably operated on conventional AVR generators. These power generation issues have been vexing set electricians for years. Use this link for my newsletter article that explains the electrical engineering principles behind these issues and how to resolve them.

Even though the poor Power Factor of an individual Litepanel will not have a disastrous effect on a portable generator, poor Power Factor should be eliminated wherever possible because its’ accumulative effect can be severe. Where just about every piece of production equipment used on set today (including video cameras, field monitors, hard-drives, lap-tops, and battery chargers) generates harmonics a viscous cycle can get started with unpredictable results like those evidenced in Kevan Shaws You-tube video.

Guy Holt, Gaffer, ScreenLight & Grip, Lightng & Grip Rental in Boston
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