How to Use a Flash Meter
Let's spend a little bit of time talking about metering the scene, 'cause this is all about learning how to use flash and understanding how bright the light should be on the subject. I've got a flash meter here from Sekonic. K this is the Sekonic LiteMaster Pro L-478DRU. All right you probably won't remember that but don't worry too much about the type of flash meter, just know it's whole purpose in life is to meter the scene and then tell you what to set your shutter speed and your aperture at. There's a bunch of settings inside the flash meter where you set your ISO. Like you tell it I'm going to be shooting at ISO whatever, let's say ISO 200, I'm going to be shooting at F5.6 maybe or and my shutter speed at that. And then you meter the subject, where the subject's sitting and it tells you how to set your aperture on the camera. It actually just meters everything and it's like a cross check. Okay the flash meter says this, I set the camera to all of the things that the flash meter sa...
ys and now I can just go shoot and I don't have to like guess any longer by looking at the back of my camera or even bring it into Lightroom. I can just see that I've nailed it. I know there's often times a lot of questions about what's the appropriate brightness to have on the subject. Well the flash meter takes all that guessing out of the equation. A lot of people when they're starting out in photography basically live and die by the flash meter. In other words, you know they do this and the flash meter says F5. and they're like oh okay, I have to shoot F5. because the flash meter says so. Hmm, it's a starting point. You may have a reason to go brighter than the flash meter says or darker than the flash meter says. Just know that the flash meter is designed to give you what I would call the ultimate or the perfect exposure. But perfect exposure isn't the best exposure. Does that make sense? Sometimes you have a decision where you want the scene to look a little darker overall. Okay well then take this and add some more F stop to it to make it a little bit darker or reduce your ISO a little bit or whatever you want to do. So I'm going to show you how we use that flash meter today but before I do I think I have a slide here that'll help you out to understand the technique. You know the whole purpose here is consistent lighting. We want consistent lighting from picture to picture to picture. And then the technique is this: on the flash meter you set your ISO and I can do that if you guys want, would it help to show it on camera? Why don't we do that. I'll hold this up for the camera ops. And, this. So we'll set ISO and over here, this is a touchscreen which is pretty cool. You just move this down or up. So we'll set our ISO and today I'll be shooting mostly ISO 200. I may go to 400 when we go to the big family, we'll see how that turns out. And then we set your shutter speed. And there's, there aren't a lot of options for shutter speed. It's basically a 60th of a second, a 125th of a second and a 250th of a second. So once those two things are set, then we're going to push this trigger here on the subject, and I'll show you how that works in just a second, and it'll tell me what aperture to set on my camera. Done, take a picture. Look at it, see what the results are. And then if you change the flash power, let's say you flash power you increase it up to half power or whatever. You do it again, push the button. It'll give you a new aperture. If you move the subject away from the flash, you do it again, it'll give you a new aperture. So that's how a flash meter works. Very helpful on set just to keep things consistent. And when I say consistent, what I mean by that is let's say you are photographing a family and you bring in one of the kids, set the kid down on the stool, you take a picture. F5.6, ding. Another kid comes in and they don't want to sit on the stool. They're like no, I don't want to sit on the stool. You're like okay, you move the stool away and now the kid's at a different heighth or a different position. You do another flash meter and it says F8 at their new position. You're like op, that's a problem. You either got to move the kid or change the power so that the brightness is the same from kid to kid to kid. Mom comes in, she's taller. Dad comes in, you know, consistency, that's what a flash meter's gonna give you. So with that I say we do it in real life, show you how this works. So welcome Brandon to the set. Give him a clap. (applauding) You ready for this?
All right my friend. So go ahead and just sit right here. To do this I'm just gonna use a small umbrella starting out today and I see, let me give you a apple box if you want. If that makes you more comfy. Better?
All right cool. To start out, keep it simple, I'm just going to use a small umbrella. We'll get into umbrellas in a little bit. And lighting equipment in a little bit. I'm gonna use my Phottix Juno. Throw that on there. And just to show you what this all looks like, on the front of my, on the front of this little flash I've got a diffusion dome. You don't always have to have the diffusion dome. If it's a fairly small light modifier like this you could just, you could almost get away with just shooting it straight flash like that. But sometimes I like to use the diffusion dome in there because what it does is it spreads the light from the flash all around. I want to make a point here: anytime you change anything in your flash set up you need to re-meter k. So if I do this and I go, direct bulb, that's a new lighting scenario. So every time I make a change you got to re-meter, you got to reassess. If you don't have a flash meter then just look on the back of your camera and see if it still looks okay. So for this I'll just use that dome. All right I turn it on, great. And I'm gonna set the power on this flash. I'm gonna start out something simple. I'm just going to start out at, eh let's do one, one quarter. I'll do a quarter power. What does that mean exactly? Well quarter power means it's one quarter of the full amount of energy that this flash could produce. So full power would be one over one. Half of that would be half. Quarter of that would be quarter. Make sense? So full down to the lowest is 128th power. So now what we do is we position this over by our subject. And we get it in the position where we thing we're going to photograph. About like that. Then we grab our flash meter and by the way this cable, or this lanyard on the flash meter, it's designed so that you can put it on your belt or you can put it on your, in your gear and then you can actually be kind of far away from the subject when you take the meter and then you, it stays here, it doesn't fall on the floor. All that good stuff, all of that good stuff. You want, you don't want to actually be in the frame with the subject 'cause that can change things up a little bit. You don't want to be like here. See what would happen if I was standing here when I did it? That's bad. So you want to be away from the lighting equipment when you take the meter reading. Okay I'm at ISO 200 and my shutter speed says I'm 250th that's all good. I put it right on his chin. And it says F5, I'll hold this up so you can see it, that camera there. F5.6 and a half. F5.6 with a little five. So what does F5.6 and a half mean? Well that's halfway in between F5. and the next stop. So what's the next stop? F8; all right well my camera doesn't have a half a stop, my camera has a third of a stop. Interesting. So you could go, let's do the partial stops. You got F5.6, F6.1, or is it F6.3? It's F6.3 and then F7.1 and then F8. So what I have to do here is I have to split the difference between F6.3 and F7.1. Some of you watching are in a classroom are like bzzt, none of this is computing. If it says F5.6 and a little bit more, just add a little bit more to your aperture. Just maybe the next step up from F5.6. Now we're going to test it and to do that, be patient with me for a second. I got to fire up Lightroom and then we're going to start a tethered session.
Can you answer a question?
Yeah this is a great time to ask a question.
How is the meter reading both in front of the subject, the light hitting the subject and the subject itself. So if you have a really very pale subject or a very dark subject, how is it reading both sides?
I love it. So I'm gonna pull away from Lightroom and answer that question 'cause it's such a great question. One of the things around exposure and exposure theory is it's always a little bit confusing initially to understand how much light does the subject need. Let's say I've got an African American subject, dark skin. Do they need the same amount of light to expose them as a Caucasian subject? Well the answer is yes. And the reason why is this: let's say that I'm standing here in this light, in the studio light and I've got a friend right here. He's Latino. Then I got another friend over here and he's African American. So the three of us are standing here. All in exactly the same light. I reflect more light. Latino guy reflects a middle amount of light and the African American guy reflects less light. It's the same amount of light hitting us, it's just how much their skin reflects back to the camera. The last thing that you want to do from a photographic exposure standpoint is over expose an African American skin face and under expose a Caucasian face. You don't want all of our faces to be the same tonality, you want us to actually be lighter, medium, and darker okay. So how does the light meter know this stuff? It doesn't. It has no idea if Brandon's Caucasian, Latino, or African American. Or if he's a, you know if you're doing pet photography. No idea if he's a black lab or a chocolate lab or a you know a white lab. Is that even a thing? Is a white lab a thing, no it's not a thing. But anyways, it doesn't care. All it cares is it's measuring what is referred to as medium tonality. You ever heard of that term before, medium gray? 18% gray or you know it's measuring based on the standard in the photographic world. And it's just saying if he was a neutral toned piece of paper, a gray piece of paper, how much light needs to be shone, shined, shined, shone? Flashed onto him so that he's exposed properly as he's exposed neutral, if he was. And if he's automatically a little bit lighter than a neutral tone thing then he reflects the appropriately amount of light. Does that help, kind of? Do you need a clarification?
No I was generally thinking of having a bride and groom in the studio and you know very white dress and a very dark black tux and so I was just a little bit confused on how the meter would tell you the correct exposure for light when you've got two very different tones going on.
I'm just gonna, because it's such a great question and I think it needs to be answered, I'm just gonna riff off of what you said and get a little bit more detailed. This happens all the time in photography where you have maybe a mixed race family. You have you know a Caucasian bride and an African American groom, something like that. Or it happens at a wedding where you've got the white dress and the black tux and both are of the same race so that doesn't matter, but the clothing is totally different. Again, back to this point. All that matters is how much light comes onto the light meter because it's assuming, the light meter's saying "hey, I'm an 18% gray. "I'm medium gray" and this is how much light you need to shine on me to make me look gray and then things that are not gray are going to come out whiter than gray which is perfect because that's what we want, and things that are darker than gray are gonna come out darker than gray which is perfect 'cause we want those things to be darker. So this is just the overall light setting for great exposure regardless of what your subject is wearing, what color their skin is, anything else. And that's why a light meter can be so powerful 'cause you don't have to go through this mental you know oh shoot, what do I do in this scenario. That said, as I mentioned about 20 minutes ago, it's just starting point. The light meter's just a starting point and you may decide, and actually you may take the picture and notice that the bride's dress is blown out. You're like, "but it's set at five six "and her dress is blinking." Okay well, something else. Maybe she was closer to the flash and the groom is farther away from the flash, who knows. And so just add some more aperture. You know get it smaller aperture or decrease your ISO. Just know that this is your good starting point.