rolling shutter and "muzzle flashes"

[Josh Bass]

Hi guys. I know you thought the day would never come, but Bass is going to shoot something that involves, you guessed it, gunplay.

This is an ultra mega micro budget short film, and as such, we are planning on never actually showing guns firing, but only the light from the muzzle flash reflecting off the actors/room. My initial idea to do this was to use a camera flash, gelled with something warm.

It occurred to me while watching a certain paparazzi-centric show the other day (forgive me I don't have cable) that this flasht thing might not work out because of the rolling shutter on the 5D. I could see on whatever video cams they were using that the camera flashes did not appear uniformly on the screen but, would show up first on the top half, then the bottom. So I tried a similar test, recording video with the 5D while using my XTI to flash the room. Of course it looked craptacular, and now I'm worried my awesome idea won't work out for us.

The director suggested a trick where you insert a single frame of white in your timeline in your NLE to simulate the flash, but I can't imagine this really looks the same, as a real muzzle flash would have a definite point of origin and cast its own light/shadow pattern.

Ideas? Thanks.

[Bill Davis]

In point of fact, "muzzle flash" is pretty complex in real life.

A good explanation is here: Muzzle Flash

If you follow their explanation, you can likely simulate something - but remember, as a light source, a pistol muzzle is small and weak.

Unless you've got characters discharging their weapons in a nearly dark environment - ambient light will rapidly knock down the effect.

Nothing looks stupider than CGI muzzle flashes during a daylight battle. That SCREAMS "YouTube" to me.

YMMV, good luck.

[Josh Bass]

You're right; I should have mentioned this.

Yes, all the gunfire takes place in relatively dark interior/night environments.

It seems like even if it doesn't light up the room like a lightning storm, there should still be some visual acknowledgement of the event.

[Bill Binder]

I think the problem (besides the rolling shutter of course) is with the speed of the strobe. Maybe you can find a way to lengthen the pop of a flash through some creative lighting tweaks. My guess is you might be able to get a length of time that to a human is still imperceivably fast, but in actuality is way longer than what a strobe would do. With that, and not much motion at the time of the flash, you might get there. Not sure though, just a thought.

[Josh Bass]

Anyone know what the magic number is? Does it simply have to be longer than a frame? (1/24 I guess)?

[Rainer Listing]

Hi Joss, Google is your friend. There are any number of images of real muzzle flashes posted by gun nuts you can use as a reference. I think you will find mostly they look more artificial than the CGI YouTube examples. In general, you are better doing it in post. Photo muzzle flashes don't look real, sensible CGI is an improvement, and boost the brightness on the same frame if you need a strobe effect. No flash from a handgun should extend more than one frame. But it's easy enough to try for yourself.

[Josh Bass]

Thanks. Maybe I wasn't clear before, we're NOT planning to show the flash itself, just the light from it on people and objects. So you will never see the gun barrel when the gun is firing.

[Rainer Listing]

No, my fault, apologies. I had to research this for a short a few years ago and jumped in. From my notes, a handgun muzzle flash (where the powder produces a flash), is about .02 sec. Color and brightness also depends on powder, bluish is OK. You can miss it if you blink; you can miss it with your shutter. So do it in post like your director suggests - blow out a single frame, don't worry about shadows, it's gone before anyone has time to think about it, you've got the bang and the eye sees what it thinks it sees.

[Josh Bass]

Regarding your notes, are we talking the real thing here or a TV/movie muzzle flash? Or are they similar enough that the difference is negligible? The camera flash thing isn't going to work. . .doesn't look like you can change the duration. So I guess it's the post thing.

[Rainer Listing]

No, I'm talking the real thing. .02sec is average, but variation was only .01sec either way. (If you see the flash on TV it can't be faster than the frame rate, which is close enough to real life - but if it takes more than one frame it looks artificial).

[John Colette]

Look at a few "Beat" Takeshi Kitano movies - particularly the Yakuza films - Sonatine, Hana Bi or Boiling point. Plenty of good muzzle flash references there - Hana Bi uses them to great effect.

I think he's also the best director that currently draws breath.

[Bruce Foreman]

Originally Posted by Josh Bass

Thanks. Maybe I wasn't clear before, we're NOT planning to show the flash itself, just the light from it on people and objects. So you will never see the gun barrel when the gun is firing.

Very rarely will a muzzle flash from .38, 9mm, or .45ACP light up anything. In a dark environment it shows as a fireball at the the end of the barrel and that's it.

The exceptions I have seen have been from .454 Casull ( a revolver load that exceeds .44 magnum) and .500 Magnum. Just at dusk I have seen those loads light up a 25 yard pistol bay at our outdoor range.

Furthermore the ammunition used by law enforcement and some of what is carried by Concealed Handgun Permit holders often has powder specially blended to eliminate or reduce muzzle flash, even at night.

So what we see in the movies looks fake and flat out is fake.