Jump to content


Photo

create background lightning flashes at night??


  • Please log in to reply
17 replies to this topic

#1 john spader

john spader
  • Basic Members
  • PipPip
  • 27 posts
  • Producer

Posted 22 March 2014 - 04:04 PM

I'm helping out on a project where a scene is shot in the woods at night. and we are needing to create

fake lightning flashes in the distance. (and just to be clear--we are NOT wanting any lightning bolts, just lighting

up the black sky through the trees like when lightning lights the skies up)

Here's our best guess so far:

using a 5k HMI about 100ft behind the subject and aimed about 60degrees up and having a big diffuser right over

the light, we'd fog up the tree areas in back, then flick the 5k on-and-off quickly as if lightning lit up the night.

 

thoughts?

 

better way?


  • 0

#2 Toby Orzano

Toby Orzano
  • Basic Members
  • PipPip
  • 80 posts
  • Electrician
  • Portland, OR

Posted 22 March 2014 - 04:55 PM

You can't flick an HMI on and off. You have to keep the head burning and use mechanical shutters if you want to make the light look like it is flickering. I know these shutters exist but I have never used them so maybe someone else can provide more information.

 

 

I have used these on a few projects with success: http://www.luminysco...htning-strikes/

 

The output per wattage is not the same as HMI so you have to go much bigger than you think. I'd say you would need at least the 70kW for this setup, maybe on a Long John Silver stand or condor. You don't need 70kW continuous power—they have the Thundervolt battery pack which powers the LightningStrike head and trickle-charges from any 20A circuit. If you go crazy with tons of lightning you may have to wait a little while between takes for it to charge back up. You have a DMX remote on the ground (or in the basket) where you can control when it fires, the speed of undulation, and the intensity. 


Edited by Toby Orzano, 22 March 2014 - 04:59 PM.

  • 0

#3 Guy Holt

Guy Holt
  • Basic Members
  • PipPipPipPip
  • 535 posts
  • Gaffer
  • Boston

Posted 23 March 2014 - 04:47 PM

Here's our best guess so far: using a 5k HMI about 100ft behind the subject and aimed about 60degrees up and having a big diffuser right over

the light, we'd fog up the tree areas in back, then flick the 5k on-and-off quickly as if lightning lit up the night. thoughts? better way?

 

I second Toby's comment that you can't flick an HMI "on" and "off." Another way to douse them is to rig a metal 4x4 flag so that it blocks the output of the light entirely from your set area. Rig it as close to the fixture as possible, but still be able to spin the flag without hitting the fixture. Now spinning the top riser of the stand the flag is rigged on will bring the light output of the HMI up and down very quickly.

 

If the area you are going to fog is 100' behind the talent and it is a large area, the light will have to be another 100-150' behind the fog. At that distance from your power source, you are likely to have appreciable voltage drop over such a long cable run. You may want to consider using for your HMI the new Arri M40 with ARRIMAX reflector. It will have an output comparable to a 6k Par and you can power it off the enhanced 7500W output of a modified Honda EU6500is. Using the EU6500is will save you having to run out hundreds of feet of cable and the consequent voltage drop. And it is quiet enough that  you are not likely to hear it at that distance.

 

Guy Holt, Gaffer, ScreenLight & Grip, Lighting rental & sales in Boston


Edited by Guy Holt, 23 March 2014 - 04:49 PM.

  • 0

#4 Toby Orzano

Toby Orzano
  • Basic Members
  • PipPip
  • 80 posts
  • Electrician
  • Portland, OR

Posted 23 March 2014 - 05:44 PM

A metal flag would sure be a heck of a lot cheaper and simpler than a Lightning Strike, not to mention also eliminating the cost and hassle of transporting the beastly ThunderVolt. Guy, have you gotten good results for simulating lightning using this technique? Any examples by chance? Is it possible to spin the flag fast enough that you don't see the edge wipe across frame as it opens up? I feel like you also need to vary the duration of each subsequent "strobe" for it to sell as realistic lightning.


  • 0

#5 ricardo aberg cobo

ricardo aberg cobo

    New

  • Basic Members
  • Pip
  • 1 posts
  • Cinematographer
  • North Miami, U.S.A.

Posted 23 March 2014 - 07:32 PM

The use of a hi-output studio strobes multiplying with mirrors.Mirror ball efect concept.


  • 0

#6 john spader

john spader
  • Basic Members
  • PipPip
  • 27 posts
  • Producer

Posted 28 March 2014 - 05:00 PM

anyone have good examples of accomplishing lightning strikes in a big area?

 

weird, I can't find ANYTHING online on ways to do this.

 

assuming I can rig it to work, you think this 5k HMI I have access to would be

enough? I'm concerned it will create a beam through the fogged woods.

 

keep it coming guys! good stuff!


  • 0

#7 Mark Kenfield

Mark Kenfield
  • Basic Members
  • PipPipPipPip
  • 1052 posts
  • Cinematographer
  • Australia/Wherever The Wind Takes Me

Posted 28 March 2014 - 05:41 PM

I'm not sure if it'd have enough output for your needs, but if you can access a rental Aadyntech Eco Punch LED, they're equivalent to a 2.5k HMI and have a built-in lightning effect, only draws 600w or something daft like that too, so could potentially lighten your gennie requirements.
  • 0

#8 john spader

john spader
  • Basic Members
  • PipPip
  • 27 posts
  • Producer

Posted 28 March 2014 - 06:26 PM

I'm not sure if it'd have enough output for your needs, but if you can access a rental Aadyntech Eco Punch LED, they're equivalent to a 2.5k HMI and have a built-in lightning effect, only draws 600w or something daft like that too, so could potentially lighten your gennie requirements.

not sure I follow the logic. if a 5k isn't enough output for our needs, why would an Aadyntech Eco Punch at ~2.5k work? 

obviously the built-in lightning option rocks! so thats good, but can these be daisy-chained to have multiple fire at once then?


  • 0

#9 Mark Kenfield

Mark Kenfield
  • Basic Members
  • PipPipPipPip
  • 1052 posts
  • Cinematographer
  • Australia/Wherever The Wind Takes Me

Posted 28 March 2014 - 08:00 PM

Well given that you seem unsure of the output you need, that you're thinking of flicking your 5kw light on and off, and the fact that the only common 5kw fixtures I'm aware of are all Tungsten lights - I assumed that perhaps you were actually talking about a 5kw tungsten fixture rather than an HMI, in which case 2.5k HMI equivalence would do you just fine.

You'd have to ask aadyntech, but the lights have full DMX so I wouldn't be surprised if they could be linked for the lightning effect.
  • 0

#10 john spader

john spader
  • Basic Members
  • PipPip
  • 27 posts
  • Producer

Posted 28 March 2014 - 08:19 PM

oh, my bad. yes, I have free access to a 5k HMI light so thats what I was referring to if that would be enough.

then since I can't switch it on and off, assuming I can find a way to flicker it with flags.

 

any thoughts on best way you would diffuse/disperse light so its not a beam and light up the whole background woods?


  • 0

#11 Toby Orzano

Toby Orzano
  • Basic Members
  • PipPip
  • 80 posts
  • Electrician
  • Portland, OR

Posted 29 March 2014 - 08:25 PM

Aha, I found one of the examples of lightning done with the LightningStrikes 70K unit.

 

 

The lightning is at 1:15.

 

The controller automatically generates undulation so you just have to hold the button for how ever long you want the lightning to last and it produces the variable flicker that you see. Nice for technicians, who don't have to stress about getting a gag right when they have no idea what it looks like on camera.


  • 0

#12 john spader

john spader
  • Basic Members
  • PipPip
  • 27 posts
  • Producer

Posted 31 March 2014 - 09:23 PM

will one of those Honda EU6500is gene give enough juice to operate the LightningStrikes 70K unit? 

I'm guessing thats not actually 70,000 watts, so whats the minimum gene power I'll need?


  • 0

#13 Adrian Sierkowski

Adrian Sierkowski
  • Sustaining Members
  • 7118 posts
  • Cinematographer
  • Los Angeles, Ca

Posted 31 March 2014 - 10:18 PM

It is 70K; but it is a trickle charge battery pack which feeds it. So you let it recharge,much as the flash in your still camera is very very very high wattage.

 

The 8K parparazzi pulles 30A.


  • 0

#14 Igor Trajkovski

Igor Trajkovski
  • Basic Members
  • PipPipPipPip
  • 289 posts
  • Other
  • Macedonia

Posted 01 April 2014 - 04:39 AM

What about using stick welder/s?

 

It seems to me they might be a bit to bluish.

 

Just an idea.

 

 

Best

 

Igor


  • 0

#15 Brian Drysdale

Brian Drysdale
  • Basic Members
  • PipPipPipPip
  • 5070 posts
  • Cinematographer

Posted 01 April 2014 - 05:33 AM

We used a welder to create electrical flashes at an electrical transformer. You'd need to test it, this worked on a localised area. I'm not sure about large backgrounds..


  • 0

#16 Stuart Allman

Stuart Allman
  • Basic Members
  • PipPipPip
  • 179 posts
  • Cinematographer
  • San Diego, CA

Posted 01 April 2014 - 02:10 PM

John,

 

I'm sure Guy will strike down this idea (no pun intended...no really), but have you thought about using a series of projectors and run a "lightning strike" video loop through the projectors?  I guess this really depends on the area involved, but it might be enough if you're using the large theater sort of video projectors.  You can also put the projectors up on tall stands so it appears that the lightning is coming from above.  A generator would easily power the projectors and laptop.  The trick would be how to distribute the video to multiple projectors.

 

Stuart

-----------------------------

illuma.blogspot.com


  • 0

#17 Adam Frisch FSF

Adam Frisch FSF
  • Sustaining Members
  • 2009 posts
  • Cinematographer
  • Los Angeles, USA

Posted 01 April 2014 - 05:43 PM

No traditional light will replicate the speed of lighting by turning it on or off. Tungsten is too slow.

 

Here's a couple of good ways to do it if you can't afford Lightning Strikes units or can't find an old carbon arc lamp you can strike with:

 

1. Get a venetian blind shutter for a 5 or 12K. Most big lighting houses still have them hidden away in the back with the old stuff. Works surprisingly well and was how they often did lighting effects back in the days. Looks like one of those things they used to have in front of lamps on ships to send morse signals between them during WWII.

 

2. Rent an Atomic Strobe. They have a single strike button that looks very realistic IF you can catch it on film. It discharges so quick, you sometimes miss it. It also can create banding on any non-global shutter camera, but not in every shot.


  • 0

#18 Mark Kenfield

Mark Kenfield
  • Basic Members
  • PipPipPipPip
  • 1052 posts
  • Cinematographer
  • Australia/Wherever The Wind Takes Me

Posted 02 April 2014 - 07:00 PM

A couple of powerful still camera strobes 1200w/s units, will also go quite a long way, and you can run them off their own portable generator (so they're a lot smaller and cheaper than film options). A couple of quick flashes will give you a basic effect and a lot of light output - though you'll get little of the decay and randomness of actual lightning.

 

It's probably the best budget option after getting venetian blinds for your 5K.


  • 0


CineTape

Willys Widgets

Aerial Filmworks

Glidecam

Opal

Wooden Camera

Metropolis Post

CineLab

FJS International, LLC

Gamma Ray Digital Inc

Tai Audio

Visual Products

Media Blackout - Custom Cables and AKS

Abel Cine

Broadcast Solutions Inc

rebotnix Technologies

Rig Wheels Passport

Ritter Battery

The Slider

Technodolly

Paralinx LLC

Aerial Filmworks

Media Blackout - Custom Cables and AKS

Visual Products

CineLab

Glidecam

Rig Wheels Passport

FJS International, LLC

Broadcast Solutions Inc

The Slider

Wooden Camera

Opal

CineTape

Abel Cine

Paralinx LLC

Ritter Battery

rebotnix Technologies

Technodolly

Metropolis Post

Tai Audio

Willys Widgets

Gamma Ray Digital Inc