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Lighting Effect

Published : 16th October 2003


Hiya

Please can any of you wonderful people offer some advice on a film I'm working on next month. I need to create a lightning effect during a fairly standard conversation scene in a daylight interior. The effect will only be seen on the character's faces in fairly tight close-ups.

My resources on this shoot are non-existent and I wondered if anybody could offer a cost-effective solution to realise this effect. Any comments more insightful than turning a light switch on and off really quickly would be really appreciated. (That's my best idea so far...)

All the best,
Liam Sanderson
Director of Photography (Ahem)
UK



>I need to create a lightning effect during a fairly standard conversation >scene in a daylight interior.

Liam,

I think this has been discussed at length some time ago on this list, so have a dig through the archives.

But for no-budget, small area, try some 'Alfoil' (aluminium cooking foil wrap) with holes cut in it, spaced well in front of a hard light source. Between the light and the Alfoil, hand-hold some form of cutter or a mirror at almost 90 degrees to the light 'beam', and have an operator rotate the mirror just so slightly.

Good luck.

Cheers,

Clive Woodward
reflecting on the moment,
Perth, Western Australia.



Hi,

One could always suggest "Toll-approach" and make it rain outside and have the trickling rain be a moving filter for the light, or, possibly a cup of coffee reflecting onto the face. All depending of course on what the effect is trying to tell the audience in accordance to script etc.

Good luck!

Sincerely

Fredrik Bäckar, DoP, Sweden.



If the lightning effect is just for a face or small area, try an HMI or blue light into a handheld mirror which you can then flicker across the face.

Cheap and effective.

Phil Curry
Dp/gaffer Austin



My cheap old method for tight to med wide shots was a couple of 1X3's with 4 medium screw base porcelain sockets on each and EAL's (Photo Floods).

Wrap it with your favourite CTB, 1/2 or full, and wire to a couple of wall switches. The bulbs are bright, and respond VERY quickly to the switch.

Years upon years of Lightning for the Count on Sesame Street was done this way. And that was back when video cameras were SLOW.

Bill Berner
191 South Broadway
Hastings on Hudson, NY 10706



Liam Sanderson wrote :

> conversation scene in a daylight interior.

So you've already started the battle uphill

>seen on the character's faces in fairly tight close-ups.

Just as important is what you see in the background, even if it's out of focus --lightning is so "broad" that you expect it to "splash" around a lot.

What I did on a seriously under equipped Music Video was to "flick" a cutter in front of a 2.5K HMI -- the effect sort of held up even for fairly wide shots but could definitely have done with some more punch out of the "lightning".

A slightly more hi-tech solution would be shutters, just make sure they're well greased, as you'll want some pretty fast flashes.

But in short -- tight enough shots, dark background, this might just work.

And btw, it's all in the wrist!

Cheers,

Kim Sarge
Sydney



The simplest method I've used are metal shutters (look like Venetian blinds) on a strong HMI -- it's like turning the light on & off but faster, crisper, without any decay or delay from switching a light on & off.

David Mullen
Cinematographer / L.A.



>The simplest method I've used are metal shutters (look like Venetian >blinds) on a strong HMI -- it's like turning the light on & off but faster, >crisper, without any decay or delay from switching a light on & off.

I have to agree. Any shutter effect is going to be much more realistic that switching lights on and off. A shutter is really easy to make out of foam core if necessary. Or a small blade venation blind works really good too.

An interesting lighting effect is with LEDs. Still working on some LED designs. Great thing about LEDs is their instant on and off ability. I have a bread board with 50 LUXEON white LEDs at 5500k. I was playing around in front of a camera with it one day and noticed that when I switched it on and off aimed at my face it look more like lightning than anything I have ever seen. At 340 foot candles, with that cool color temp, and the way LED light looks bare, it makes a nice lightning fixture for close ups. You ought to see the version I have with 200 LEDs. You don't want to be standing in front of that when its switched on.

Walter Graff
NYC



Walter Graff wrote :

>...You ought to see the version I have with 200 LEDs. You don't want to >be standing in front of that when its switched on.

How are you powering them--voltage--and how many do you have wired in series?

Wade K. Ramsey, DP
Dept. of Cinema & Video Production
Bob Jones University
Greenville, SC 29614



You never want to put LEDs in series. Not the right way to work with them. Good way to seriously shorten their life let alone alter the output characteristics.

I am using various parallel matrixes along with xitanium drivers.

Walter Graff
NYC



>I have to agree. Any shutter effect is going to be much more realistic >that switching lights on and off.

Although sometimes sound won't allow that to happen too easily.

The on/off method can be effective but that lighting units MUST be of a small filament design. I suggest the PAR lamps either singularly for close-up or the maxi brute multiple-bulb variation of the same lamp. I have used this method in a pinch and it worked surprisingly well. Decay time is smaller due to the small filament. This method definitely won't work on a 10K with it's large filament and long decay time.

Hope this helps.

Jim Sofranko
NY/DP



Walter Graff wrote :

>Great thing about LEDs is their instant on and off ability. I have a bread >board with 50 LUXEON white LEDs at 5500k. You ought to see the >version I have with 200 LEDs.


Oh that sounds rather expensive!

You're not running them in series directly from the mains with a rectifier, resistor and cap are you!!!

I've been playing with a cute little lamp recently. It's a bit larger than a pygmy bulb, but is loaded with 19 LEDs clustered together, and run directly from 240V with a simple capacitor, resistor, rectifier and smoother arrangement.

OK, it's rated less than 2W which rules it out for anything other than a fill light, but it's coolness, weight, colour purity and brightness for that power is very pleasing. The circuitry is so simple and proven, that it should last the full life of the LEDs.

Shame they're a bit pricey, 'cos I want more.

Clive Mitchell
http://www.bigclive.com



David Mullen writes :

>The simplest method I've used are metal shutters (look like Venetian >blinds) on a strong HMI -- it's like turning the light on & off but faster, >crisper, without any decay or delay from switching a light on & off.

Nobody's mentioned a Lightning Strikes type strobe. Is this because of the expense?

Another option in a well equipped studio might be to use an intelligent light, and chop it's output with a sequence of shutter operations.

(Not as simple as a big light and a mirror/shutter though I suppose...)

Clive Mitchell



Walter Graff writes :

>You never want to put LEDs in series. Not the right way to work with >them. Good way to seriously shorten their life let alone alter the output >characteristics.

I hope you mistyped that there!

The wrong way to use LEDs is in parallel, since several LEDs from the same batch could have slightly different forward voltages, and the ones with the lowest will hog the bulk of the current. This only tends to be done on cheap consumer goods like torches as an economy measure during manufacturing.

Running large groups of LEDs in series with a common current limiter is the normal approach, since the current will be the same through all the LEDs in the circuit.

If doing a large parallel group of series circuits, then each string should have it's own resistor.

Clive Mitchell



>Oh that sounds rather expensive!


About 150 pounds worth. But remember my lamps last 11 years. LEDs are the future of all lighting.

Walter Graff
NYC



>Running large groups of LEDs in series with a common current limiter is >the normal approach, since the current will be the same through all the >LEDs in the circuit.


It did not come out right. I am working with hundreds at a time in arrays and to run them in series is a disaster and takes lots and lots of current. So I work with small sets of series that then are grouped in parallel with capacitors making up for lost stability. All supply voltage is regulated. If you were running a few LEDs such as two or more in parallel, you need to using the same series resistor across each, as different LEDs will draw slightly different currents and you could burn one out faster by having them in simple parallel without any protection. Some of my designs have a resistor per LED. The easiest way to string a few LEDs together in series is to make sure you have the right number of LEDs for the voltage you are supplying. In series LEDs limit themselves. Also never use more than 80% of your supply voltage in this set-up if you want stability and a predictable current consumption. But when you are talking about 100-500 LEDs at a time as I am working with you need to create matrixes of LED groups.

BTW if anyone wants, send me your flashlight and I'll do a LED mod. Cost varies depending on the instrument and what I feel I can put in it. I am not working with off the shelf store bought diodes but really bright ones.


Walter Graff
Producer, Director, Creative Director, Cinematographer
HellGate Pictures, Inc.



Lightning Effect. Hmmm...

Why not try this :

Buy a bunch of disposable flash cameras. Have an assistant flash two or three at almost the same time. Try minor variations on the timing. If firing at close range, gel or foil-pinhole as needed to control intensity. If you fire from a ladder outside a window you'll silence the cameras and can better emulate the natural angle of incidence. Appropriate sound FX should complete the illusion.

Dan Drasin
Producer/DP
Marin County, CA



Walter Graff wrote :

>About 150 pounds worth. But remember my lamps last 11 years. LEDs >are the future of all lighting.


11 years if you heat sink them properly and make sure that the circuitry driving them can't do anything unpleasant. The theatre industry is rife with super duper Luxeon colour changing fixtures, and they have pushed the limits in every way. I'm a strong proponent of at least having a low speed quiet fan to keep the temperature of the Luxeons down.

Clive Mitchell



Walter Graff wrote :

>It did not come out right. I am working with hundreds at a time in arrays >and to run them in series is a disaster and takes lots and lots of current.

No! To run them in PARALLEL takes lots of current. Running them in series requires a constant current with a voltage proportional to the total voltage drop of all the LEDs.

>The easiest way to string a few LEDs together in series is to make sure >you have the right number of LEDs for the voltage you are supplying.

If you string a lot of LEDs in series, then you should always include at least a series resistor to limit the current through the chain. LEDs do not reliably regulate themselves to a changing voltage out with a very small range. As the voltage increases they reach their forward voltage and then generally start conducting like hell.

If you are trying to run large arrays directly from the mains through a rectifier and capacitor arrangement, but without a series resistor, then you are going to end up with a lot of fried LEDs. Mains voltage can fluctuate wildly depending on the neighbourhood, and generators are never to be trusted for a fixed voltage output. Particularly when someone does something dodgy like turning the output voltage up to compensate for voltage loss in a long run of cable. AVR's (Automatic Voltage Regulators) on lighting sets can also do odd things when they expire.

If running a large series group of LEDs from a directly mains derived supply, then a high voltage current regulator circuit with auxiliary crowbar facilities for fault conditions would be a good bet.

Clive Mitchell



>No! To run them in PARALLEL takes lots of current. Running them in >series requires a constant current with a voltage proportional to the total >voltage drop of all the LEDs.

Clive I have been doing testing with LEDs for the last five years.

$10,000.00 later I can assure you in cases of many LED, you do not want to run them in just a series configuration. In fact at the last LED designers conference I went to in April that was the talk of two lectures. Sure you can, but the best thing to do is to group series with parallel. Sure it requires more current, but it is more efficient and reliable.

Walter Graff
NYC



Walter Graff wrote :

>Clive I have been doing testing with LEDs for the last five years
.

Are you talking about multiple parallel circuits in series? Or multiple series circuits in parallel?

Having used LEDs extensively for illumination and decorative purposes for well over 20 years I've seen them grow from mere indicators into the current high output light sources. The technology seems to have a bright future (if you'll excuse the pun.)

Clive Mitchell



Thanks for all the feedback.

All the best,

Liam Sanderson