Blowing up a light bulb!

Jordan Watson · July 3, 2014

Hey guys,

Part of the storyboard I've been given for a client requires a light bulb to be blown up. It's for an electrical engineering company. What is the best way to do this? Using a high frame rate would look best.

Would it be better to see if a VFX company can achieve this? Or is hiring a high frame rate camera + hiring specific crew for the shoot a better option?

Thanks in advance,

Jordan W

Satsuki Murashige · July 3, 2014

Can you be more specific about what exactly the shot is supposed to be?

Is it a wide, medium, CU or ECU of the globe? Is it in a practical set like a bedroom or on white or black cyc? Is the globe screwed into a lamp fixture, ceiling socket, just laying on a table? Does the globe need to be lit? Clear or frosted? How many seconds do you need to stretch out the action of the bulb exploding?

Jordan Watson · July 3, 2014

Hi Satsuki,

It is a CU on a black backdrop. The globe is screwed into a lamp fixture but without the 'shades'. The fixture will be on top of a table but will not be seen. The globe is turned off at the start of the shot, and then turns on ... gradually getting to the point where it explodes (too much current). This will last about 7 seconds approximately.

Cheers,

Jordan W

Phil Rhodes · July 3, 2014

See if you can obtain a 110V lightbulb (or rather, several, for tests and screwups) and a variac? That way you can ramp the voltage up to failure point.

As to shooting it, the fastest affordable camera is probably an FS700 - they'll do up to 960fps at reduced quality, or 240 at HD. Otherwise you're into the super-expensive realm of Vision Research products.

P

Keith Walters · July 3, 2014

If by "explode" you mean shatter the glass envelope, it would take a hell of a whallop of current to do that. All you're likely to do is blow the filament.

Also, in Australia at least, you can't buy ordinary 240V incandescent bulbs any more, all you can get are small quartz halogen lamps mounted inside a glass envelope so they look like an old-fashioned lightbulb, and it's almost impossible to get one of those to explode on cue.

You would probably need to shoot it with an air rifle or something similar.

I suppose you could fake it by removing the glass from a car headlamp bulb and fitting the 12V filament assembly inside the outer glass envelope taken from a 240V quartz halogen type, and then hitting it with 240V, but that would be a seriously dangerous undertaking unless you knew what you were doing.

Stuart Brereton · July 3, 2014

If you Google magic supplies, you may be able to find the gimmick device that magicians use to perform this trick on stage. I've only seen one once, but i remember it looking like a tiny spring loaded hammer.

Satsuki Murashige · July 3, 2014

Yeah, you may need to break the glass with a squib or a specialized rig. Safety first! Make sure you get a large sheet of Lexan for the camera and anybody who has to be nearby.

For a 7 second explosion, you're gonna want to rent a Phantom. The FS700 is decent up to 240fps, but the image quality is pretty bad at 480fps. You might as well shoot with a potato at 960fps. 1sec of action expanded to 7 seconds of movie time would require 1600fps. You may not even get an exposure from the filament at that speed and it will flicker quite a bit. If you can test at a rental house, that would be ideal.

Lance Soltys · July 3, 2014

Have you thought of looking at stock footage collections? Seems like something they would have, and maybe cheaper than renting equipment.

Jordan Watson · July 4, 2014

Thanks Phil I think the FS700 is the way to go! Thanks for all your replies, it looks like getting an air rifle would be the best way to go. I will also look up magic supplies and some stock footage to look for cheaper / quicker solutions.

Cheers,

Jordan Watson

Chris Millar · July 4, 2014

Also, in Australia at least, you can't buy ordinary 240V incandescent bulbs any more.

We smuggle them in from New Zealand - in winter, they provide heat :rolleyes:

Patrick Lewis · July 5, 2014

I was thinking about this a while back. I wanted to explode a light bulb. Never did it, but I've heard that if you spray a hot light bulb with water (like from a spray bottle), it will thermal shock the glass and shatter the bulb. If you don't want the water in the shot, maybe try spraying from behind the bulb. Hope this helps. So maybe get the bulb good and hot, shut it off and start rolling. Then do the 7 seconds or so of fading in and spray a stream of water at it.

Edited July 5, 2014 by Patrick Lewis