Dialing in the Flash Exposure
So for normal flash exposures, I would typically use the light meter, and in the old school flash world, your aperture setting controls the brightness on your subject. So if somebody's shooting me here, the aperture changes how bright I am, or how much light is coming in from the flash. And the shutter controls the brightness or darkness of the background, which is really easy, because you could actually just, okay we're shooting, your subject's lit perfectly but you want the background darker. Well you just crank up your shutter speed to maybe 2/50 of a second from 1/25 of a second. Or if you want it brighter, you just lower your shutter speed down to 1/60 of a second or something. So it's very intuitive, but you kinda have to throw that all out the window because we have an extra variable. We have the power of the flashes, the aperture, the shutter speed. And then we have, as you raise the shutter speed, you're using a smaller and smaller slice of the light. So it makes it a little m...
ore complicated, which I know that sounds nutty right now, but hang with me. So we throw this all out the window, 'cause it doesn't work. I've laid out this super simple thing that I follow myself, because I had to dumb it down for myself when I'm in the field, okay how do I actually get the right exposure? It's the same things for normal flash photography. You find the angle you're gonna shoot from, you find your composition. I pretty much always shoot in manual exposure mode, 'cause the lights are in manual, there's no TTL or anything like that with this system. Then I use my camera's light meter and I measure, I take a picture of the background, and I dial in the background to the correct exposure. Using the histogram, it may or not be what the camera tells me is zeroed out at the correct exposure. But I dial it in with the histogram to get it right where I want it. And then, once I've got the background well exposed, that's when I make a decision. Do I want the background one stop darker, half stop darker, equal to my exposure, or do I want the background brighter, which in some situations would work. Today I'm probably gonna want the white wall a little darker than the subjects so that they pop off the wall. I might go a half stop or a stop, but I make that decision right now. And what I do is, once I've made that decision, I basically raise my shutter speed or my aperture to change it so the exposure's one stop darker than the correct exposure, or whatever setting I'm gonna end up using. And then you position your subject, you position your lights just like normal, and then you basically take a test shot with whatever settings you've set and whatever settings you have on the lights. Typically I start out at full power, just to know that I have enough power to do what I'm gonna do. And then I turn the power on the pack down or up until it's registering a good exposure on the subject. How I figure that out is usually in the field that's on the LCD of the camera, and I have my camera calibrated to some degree, so it's the same brightness as my monitor which is calibrated at home. I use a Hoodman loupe that blocks out all the ambient light, so that I know when I'm looking at the back of the camera it's not having a whole lot of light contamination, 'cause it's really hard to see outdoors. Here we're gonna shoot tethered, so we can see it on the monitor, and this is a calibrated monitor, but I'm also looking at the histogram, everybody knows about histograms. I'm looking at that right side to make sure there's not some giant gap of underexposure. So there's a couple different tools we can use to gauge the exposure. And here's the deal, if you want to like this last step, if you want to change your lighting ratios on your background, then you have to go back to step four, where you decide how much you underexpose or overexpose and start over. So as I'm shooting, I kind of memorize that initial exposure of the background. So let's say it's 1/2000 of a second at F4, ISO 200, whatever it is. I'll just memorize that and be like okay, that's my baseline. If I need to go back and say I wanna be a half stop under instead of a full stop under, I'll start back there, then we'll redo the lighting. It's a little bit more work to redo it, but it's not that hard, and once you get used to it a few times, it goes really fast.