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Bomb blast simulation


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#1 Andrew Brinkhaus

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Posted 03 August 2008 - 12:29 PM

Dust shakes loose from the teak rafters as bombs collide with nearby buildings. Another blast illuminates the room.

Ok. Sounds simple, but could be interpreted a dozen ways. How often do we actually see an illumination from a bomb blast? I think color is the most important element to recreate here. I think this could look cheap very easily as well. I don't get to location for another month, and don't have the resources right now to test it myself.

Initially I am thinking of maybe two 5K's through the window, on Flickermasters or a dimmer of some kind. I think the light should kick on, as the light from the explosion emits, and then quickly fade back down. So a very quick fade up, almost instant, and then a slower fade back down. I don't think the light should peak for no more than a second at most, however.

Anybody have any suggestions or starters?

Edited by Andrew Brinkhaus, 03 August 2008 - 12:30 PM.

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#2 Andrew Brinkhaus

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Posted 03 August 2008 - 07:23 PM

How would some of you guys approach this?
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#3 David Mullen ASC

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Posted 03 August 2008 - 11:05 PM

How would some of you guys approach this?


I'd probably put some 12-lights or something on a dimmer board. You could flag them and pull the flags for the initial flash, or use a couple of large fresnels with metal venetian blinds for the initial flash.
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#4 Satsuki Murashige

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Posted 04 August 2008 - 02:29 AM

One crazy thought - if you don't have enough wattage to pull this off, how about flashing the negative in camera for a brief second? If you're using a 35mm camera, you could open the door of the camera body at the right time. Combined with some camera shake, plus debris and smoke from art dept, you might be able to pull it off.

This technique was used by Slawomir Idziak on "Three Colors: Blue." He wanted a momentary blue wash on a character's close-up so he wrapped the camera body in a blue gel before flashing the film.
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#5 Ryan Patrick OHara

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Posted 04 August 2008 - 04:04 AM

One crazy thought - if you don't have enough wattage to pull this off, how about flashing the negative in camera for a brief second? If you're using a 35mm camera, you could open the door of the camera body at the right time. Combined with some camera shake, plus debris and smoke from art dept, you might be able to pull it off.

This technique was used by Slawomir Idziak on "Three Colors: Blue." He wanted a momentary blue wash on a character's close-up so he wrapped the camera body in a blue gel before flashing the film.


Cool idea, except if the bomb blast light were to be coming through a window or etc, the shadows or non-direct recipient of the bomb blast light would lighten equally. It might still pull off, but it's most likely best to have a source.

Perhaps your idea would be a great supplement effect with the use of a hard source flash.

Either way that was good outside the box thinking!



My opinion on the matter is that an explosion is usually an immediate burst, but the initial flames/energy has a slower fall off as it dissipates. So a sudden bright flash with a quick falloff would look best. Watching explosion videos, the explosion is always a blast of powerful 'white' light, followed by the falloff being orange-red flame like. What is really going to make the effect convincing is camera movement and audio effects. Best of luck!

Edited by Ryan Patrick OHara, 04 August 2008 - 04:08 AM.

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#6 Ryan Patrick OHara

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Posted 04 August 2008 - 04:16 AM

Cool idea, except if the bomb blast light were to be coming through a window or etc, the shadows or non-direct recipient of the bomb blast light would lighten equally. It might still pull off, but it's most likely best to have a source.

Perhaps your idea would be a great supplement effect with the use of a hard source flash.

Either way that was good outside the box thinking!



My opinion on the matter is that an explosion is usually an immediate burst, but the initial flames/energy has a slower fall off as it dissipates. So a sudden bright flash with a quick falloff would look best. Watching explosion videos, the explosion is always a blast of powerful 'white' light, followed by the falloff being orange-red flame like. What is really going to make the effect convincing is camera movement and audio effects. Best of luck!


Sorry to double post but I can't seem to edit the post. The falloff I refer to is the one you described Andrew... very fast. So when I say "slower falloff" I mean "not instant".
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#7 James Steven Beverly

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Posted 04 August 2008 - 05:24 AM

Depending on the circumstances, I'd probably use flash-pots BUT you would have to find someone qualified to set them up and fire them. Maybe a still camera flash unit would work . A lot of it depends on Context of the scene, how big the bomb is and what kind of bomb. A big bomb would have an afterglow. Incendiaries would start fires. An averaged size standard military ordinance 250 to 500 lb high explosive aerial bomb is gonna be a huge flash. If it's a bombing raid, you'd have overlapping flashes of varying intensity depending on where the bombs were hitting relative to the widows in the room in addition to the close bomb. You may want to bounce the flashed light off reflectors to give it a wide spread so it fills the room at almost all angles like a large intense white fireball explosion would. A couple of maxi s would work. If it's an air raid, I'd add some smaller lights at various distances flashed randomly to simulate a lot of bombs falling on the city. A close explosion from a bomb might also shatter the windows from the concussion. You could use a compressed air Trunnion Gun and sugar glass or maybe tempered glass for that (PROVIDED that gag is handled by qualified people and all safety precautions are in place).
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#8 Andrew Brinkhaus

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Posted 04 August 2008 - 10:23 AM

Thanks for the replies so far guys!

I've decided after watching all the blast and explosion videos I could find on YouTube that, similar to what I thought initially, a very quick "punch" of light, and then a slow falloff will be the most realistic.

Depending on the layout of the room, and the number of windows, I think 2 5K's flooded in each window should be enough. This will be a great contrast because the rest of the room will be very dark, "unlit" only the ambient light from the windows illuminating the room. This will probably be achieved with china lanterns gelled and put on dimmers hung throughout the room.

Now I'm trying to figure out the best way to control the light. David mentioned flagging them and quickly panning them away on que, this could work well if they were hooked up to Variacs, and could be faded by hand. This would give us the most control over adjusting speed, timing, etc.
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#9 Phil Rhodes

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Posted 04 August 2008 - 10:32 AM

I'm not quite sure we're all thinking about this in the right way. It depends how far away it is, of course, but a single explosion will create a point-source light. Real military explosives produce very little fire and will probably appear as a single-frame orange flash. If you want to suppose it's hitting something flammable, then that light will be very orange and move upward, causing shadows thrown by windows and so forth to move downwards. Unless it's supposed to be the light of a very large, very fiery nearby explosion I can't see it being anything other than a fairly sharp source.

P
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#10 Andrew Brinkhaus

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Posted 04 August 2008 - 10:38 AM

Phil, I agree. I think the source should be pretty sharp. Obviously though, this largely depends on the distance of the blast.
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#11 David Rakoczy

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Posted 04 August 2008 - 12:20 PM

I've used Propane Blasts off Camera...
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#12 Jim Keller

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Posted 04 August 2008 - 12:29 PM

You may also want to consider simply gelling a strobe light.
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#13 Freya Black

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Posted 04 August 2008 - 12:54 PM

I'm assuming this is a low budget shoot.

The truth is that theres nothing like real explosions. You can try to fake them with cgi or with weird lighting tricks but at the end of the day you run the risk of making your film look like a cheap Briitish tv war drama.

No what you really need is genuine explosives and the wonderful thing about having the internet these days is it's easy to find all sorts of DIY recepies for explosives that you can make at home with parts from your local garden centre/hair salon. Of course it is somewhat time consuming but this is probably a great job to delegate to the runner/intern to enhance their opportunity, after all their career in film may not work out but they will still have gained some useful chemistry skills that might be transferable to another occupation, so it could really work out to benefit them either way.

Of course, as this is a low budget shoot you are likely to have some serious injuries among the crew, this is par the course as most crew will be expecting to be going home in serious pain even after a more conventinal low budget shoot but you really need to be careful not to have any fatalities. Keep an eye out for the possibility of local pet animals wandering into the blast field. I can absolutely guarentee that your insurance won't cover you for fatalities of ANY kind in this context.

Best of luck with your shoot I'm sure it will be a blast! :)

love

Freya
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#14 John Holland

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Posted 04 August 2008 - 01:01 PM

Love it Freya . You prob. have the fuzz bomb squad on your doorstep this evening . :o
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#15 Phil Rhodes

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Posted 04 August 2008 - 02:03 PM

Fish-tank oxygenating tablets and powdered sugar.

"Foolish humans!"

"Oh, yes, Kodos..."
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#16 Joe Giambrone

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Posted 04 August 2008 - 06:45 PM

Well, before you get to the do it yourself school of explosive making, perhaps something a little more old school would do the trick.

You mentioned rafters and dust.

Build yourself very loose rafters and/or windows with lots of dust. Use brawny men with sledgehammers to whack it as the light flashes, so the percussion is timed to quickly follow the flash.

For a window this would be very effective. The window could smash in and the frame shatter from the blow of a sledgehammer on the other side of the wall.

Modern military bombs use high-velocity explosives that expand at 20,000 ft. per second from the source. Most Hollywood failures at simulating this use kerosene or gasoline (orange/black cloud) that expands much slower and looks completely different. Look into it.
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#17 Andrew Brinkhaus

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Posted 04 August 2008 - 08:26 PM

Well I should mention that the film takes place in 1974, so not exactly modern warfare.
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#18 Jon Rosenbloom

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Posted 04 August 2008 - 08:33 PM

Camera shake + dust + lightning strikes.
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#19 James Steven Beverly

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Posted 05 August 2008 - 01:43 AM

Well I should mention that the film takes place in 1974, so not exactly modern warfare.


No, we had bombs back in 1974. See throwing rocks and sharp sticks fell out of favor in 1972. The bombs were a little different though, they were made out of buffalo hide, filled with bear dung and stitched together with sinew. We put goose feathers at the back so they'd fall straight. We didn't have planes back then so we had to drop them out of very tall trees which REALLY limited our target range to pretty much just the guys that walked under the trees. They didn't actually explode per se', but they made a big brown puff if you did hit the enemy with one and they smelled like bear crap for weeks, which essentially took them out of the war because no one wanted to get into a foxhole with that guy. :rolleyes:

Edited by James Steven Beverly, 05 August 2008 - 01:45 AM.

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#20 James Steven Beverly

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Posted 05 August 2008 - 01:46 AM

I'm assuming this is a low budget shoot.

The truth is that theres nothing like real explosions. You can try to fake them with cgi or with weird lighting tricks but at the end of the day you run the risk of making your film look like a cheap Briitish tv war drama.

No what you really need is genuine explosives and the wonderful thing about having the internet these days is it's easy to find all sorts of DIY recepies for explosives that you can make at home with parts from your local garden centre/hair salon. Of course it is somewhat time consuming but this is probably a great job to delegate to the runner/intern to enhance their opportunity, after all their career in film may not work out but they will still have gained some useful chemistry skills that might be transferable to another occupation, so it could really work out to benefit them either way.

Of course, as this is a low budget shoot you are likely to have some serious injuries among the crew, this is par the course as most crew will be expecting to be going home in serious pain even after a more conventinal low budget shoot but you really need to be careful not to have any fatalities. Keep an eye out for the possibility of local pet animals wandering into the blast field. I can absolutely guarentee that your insurance won't cover you for fatalities of ANY kind in this context.

Best of luck with your shoot I'm sure it will be a blast! :)

love

Freya


Nikki, is that you? :unsure:

Edited by James Steven Beverly, 05 August 2008 - 01:47 AM.

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