Flashing effect...detective story

[Daniel Tan]

Hey everybody,

 

I'm starting a shoot and is in need to find out how to do the effect of a flash going off in a scene hitting the camera except that the flash will not be in the shot. I have a couple of crimes scene with dead bodies and would like to cut to another using the flash as a transition. (I hope I am not making confusing by explaining unclearly)

 

I know it can probably be done in post...just wondering if it is better to do it on the set to achieve a more natural effect.

 

Thanks.

 

Regards,

Daniel Tan

[Eric Steelberg ASC]

You can rent a buch of concert size strobes and slave them together to all go off at once.

[Phil Rhodes]

Hi,

 

You need to be very careful using actual xenon strobes. The flash is extremely brief and you have a 50% chance of losing it in the pulldown/vertical interval as appropriate. Find, if you can, some magnesium flashbulbs. You can buy them with edison screw bases (try pyrotechnics companies) although they're normally best fired with a 12V car battery (don't put them on the mains!)

 

They burn for much longer. Stand well back though - you don't have to be physically touching the plastic bulb to be burned, as the incredibly intense pulse of infra-red will happily flay the flesh off any fingers within a half inch or so.

 

Phil

[John Pytlak RIP]

There are dealers who specialize in old flashbulbs:

 

http://www.flashbulbs.com/index.shtml

 

http://www.flashbulbs.com/flash_info.htm

 

http://www.apogeephoto.com/mag2-6/mag2-9flashbulb.shtml

 

http://digilander.libero.it/fotoantiquaria/photolinks.html

 

http://www.stereophotoworld.com/generalaccs.asp

 

http://medfmt.8k.com/mf/flashbulbs.html

 

http://photography.about.com/library/dop/bldop_hedger.htm

 

You definitely want a flash that produces a relatively long burst of light, so you don't need to worry about sync.

 

A neat scene transition would be a close up of the flash as it goes off, then takes a few seconds to cool.

[Mitch Gross]

If you wish the entire frame to white out momentarilly, you could simply insert a frame of clear leader into the edit (one white frame in video). Works pretty well, especially with a sound effect.

[DanStewart]

Just wandering what the effect would be of shooting a flash in slo-mo..? If you're going digital post you can always increase the speed back up to realtime, but perhaps you'd capture more detail in the effect? In any case your editor would probably thank you for it.. :huh:

[AStar]

One way that come to my mind is to do a lock off on the frame and shoot some normal footage and then some long exposure footage of the same frame. Then have your editor do a very quick (only frames long) dissolve between the differnent frames. This way you have control of how long you want the overexposed (flash) material to be on screen. You could ramp into the flash or the flash could have a longer decay into changed material.

 

The white leader idea is a very simple plan that you could augment by replacing the leader with some subliminal messaging like Death, Evil, Murder, or overexposed shots of the killer thrown out of focus, whatever.

 

The slo-mo flash idea might not work, since most flashes last only 1/500 to 1/50,000 of a second. You would need a frame rate in the tens of thousands to capture it slo-mo, something close to the bullet high-speed.

 

A

[Phil Rhodes]

Hi,

 

Magnesium flashbulbs last a lot longer, but I'm pretty sure that all the examples of the flashbulb closeup I've seen have been shot slow motion.

 

You could always connect some kind of really fast remot control assembly to the iris and just pulse it open, although you might have trouble making it happen fast enough - as well as possibly wrecking the lens!

 

Phil

[Nate Downes]

Use a 5k light attached to a flip switch? flip it on and off rapidly?

[Luke Prendergast]

Ditto the 5k. Strobes are a pain unless you need extreme amounts of light. I've been looking for an excuse to use LightningStrikes but unfortunately the manually controlled 2k or 5k (or multiples thereof) has always been more appropriate.