Metering Basics for Studio Strobes
We're gonna talk about in this session, metering, that's where we're gonna start. With speed lights and with natural light you can use the built-in light meter on your camera to figure out the proper exposure most of time that we know about the TTL wackiness and exposure compensation and all that kind of stuff, but with a studio strobe, you have to use a light meter most of the time. Now there is an exception to this rule and it's this new light that just came out a few months ago. This is the Profoto B1. This is the first studio strobe that is full TTL. You can now use this guy wirelessly, it's totally battery contained and you can shoot this just like a speed light, except for it doesn't have high speed sync. So it does everything else that a speed light does with no high speed sync and so with this exception and I'm guessing that there'll be other manufacturers that have similar lights sometime along the way. The thing that's happening now in studio lighting is there's now a shift t...
o TTL studio lighting. We're not gonna do that today, we're gonna teach you how to use a light meter and how to do it the old fashioned way. But these guys are really awesome, I've been using them for a few months now. We're gonna start by showing you how to use a light meter and why you need to use a light meter. So why is that? I have a video and here is the video coming up.
There are two basic methods of metering light. Incident metering, and reflective metering. Your camera's built-in light meter uses reflective metering. Here's how it works. Light travels from its source and reflects off the subject and into your camera's lens. When the light enters your camera, it travels down the lens and then hits a mirror. The light is then reflected at a 90 degree angle up into the pentaprism and finally out the eye piece. The mirror and pentaprism allow us to see exactly what's coming through the lens. Your camera's light meter is inside the pentaprism. This built-in light meter is what your camera uses to show you meter readings in the view finder. Some of the light is allowed to travel through the main mirror and hit a secondary mirror. This smaller mirror reflects the light onto the auto-focus sensor. This sensor is what your camera uses to focus the lens. When you press your shutter release button, both of these mirrors move out of the way, the shutter opens and the exposure is made. When you're using flash heads that are synced to your camera, they don't fire until the shutter is completely open. Which means that your built-in light meter has no way of seeing and metering this light. For studio work, you'll need an incident light meter. Instead of metering light that reflects off the subject, incident meters measure the light that is actually falling on the subject itself. You simply place the meter next to your subject and take a reading. In a normal studio setup, you'll set your camera and light meter to the same shutter speed and ISO setting. When you take a meter reading, the light meter will tell you the correct aperture value and you'll set your camera accordingly. Once you're all set up, you'll only have to worry about the aperture value.
Alright, so we're gonna start by showing you how to use a light meter. Lex has joined us again out here, and we're gonna show you the basics. But before we do, we need to sorta get a closeup on this so I can show you the different modes on this light meter. This is the light meter that I showed you previously. The thing that this has in it, this light meter, it has this little pocket was your transmitter built-in. When I'm pushing the measure button, this is actually sending a signal to the PocketWizard that's on my flash and it's making that flash fire. So that's how I'm controlling this with a PocketWizard. That flash also has a Profoto Air System, and that's what I have on the camera, so we're using two totally different triggering systems simultaneously and I'll sorta walk you through that. For those of you at home, don't get confused, we're using both of them at the same time. Okay, so what I've done here and I think we have that where you can see that, cool. Cool. Alright, so at the top here we have different modes. When I push the mode button and roll this jog wheel, we're going through these different modes. This is for ambient light. This guy right here is for studio strobes and it's called, allows you to push this metering button and it waits for a flash to fire and then it gives you a reading. We don't need that 'cause we actually have a radio. The next mode, is if you have a cable to connect your light meter to your flash. That's how it used to be done. You would actually have a physical cable that would tangle you up and make you fall over. So we're not gonna use that cable. The other mode that's next to that, if I push mode and go one more, this is the radio triggering mode where I can remotely trigger a studio flash. So right now it's saying what channel are we on. I'm on channel one, and so that works. I can change that to any of the PocketWizard channels. And then I could push mode again and go to the next thing and that's telling me I'm ready to go. So what we need to do here because we have sync speed issues to work through, I always set my shutter speed here to my camera sync speed. The 1DS Mark III or the 5D Mark III that I have here, the sync speed is about 160th of a second. Sometimes 200, it's got sort of a, the 5D Mark II is really clunky so I always go with 160. But this guy, I'm gonna go with 160 or 200. We'll see if we get any sync speed issues with some bending at 200, maybe not. All cameras are not created equal, some of them have better shutters than others. We'll start at 200 and see how it goes. I've already set my ISO to 100, which is where my camera is set. And then the only thing I have here is this zero telling me what the aperture value is going to be. As we just saw on this video, when you're metering for studio lighting, really, once you set your camera's ISO and shutter speed, it's only the aperture that you're metering for. It's really common in a studio environment, if you have an assistant or somebody metering, all they're calling out are aperture values. So the metering go, oh that's 10. What they mean is it's f/10. Or that's 5.6 or whatever. That's really the only thing that you're setting is that third part of the exposure triangle. I'm gonna do this really quickly to show you how it works. We're gonna turn on the modeling light so that we can see what we're doing here. Oh, isn't that nice. We can actually see the light that we're working with without having to guess, and this is one of the things I love about studio strobes. For those of you who've never with studio strobes, the modeling light, what it does is it tries to give you a preview of what the flash is going to look like. It will not give you an accurate representation of what that is. Because it's not as strong, it's different colored temperature, because of the strength of the light, the light fall off is gonna be different. There is all kinds of things that are happening there but at least it gives you an idea of the shadows and if the light is far enough away or high enough, you know, that type of stuff. It's much easier to dial your lighting in, when you have that modeling light turned on. The reason that you might wanna turn it off is if you are changing modifiers, it will blind you or the model, and so you can turn that light modifier, or the modeling light off, change that out. Or maybe if you have a light, this special light on a certain area, it doesn't really matter. You can turn those on and off. The other thing you can do is the modeling light will have most flashes, there's a setting to make that modeling light proportional and so when you increase the power of your flash, that modeling light gets brighter, and when you decrease the power of your flash, it gets dimmer. I don't usually use that. The reason that that's there is, to give you a preview of what the light ratios, like is this one brighter than this one? What it's gonna look like? But it almost never, in fact I've never seen it match with the actual flash looks like. So I usually don't use that. The times I do use that is if I have, like we had yesterday when we had these large hard light modifiers. A lot of times it blinds the model. There's so much light coming out, and in that case, sometimes I'll turn that modeling light down so it's just not totally blinding the person. Okay, I wanna start by metering this and showing how this works and then we're gonna give you an overview of how a basic studio light works. 'Cause all the studio lights, doesn't matter what brand that you're using, have similar controls. We're gonna walk through what those controls are but before we get sidetracked by that, I just wanna show you how to meter for studio light. It's the simplest thing ever. Let's pretend this light is in the correct position. We've done all the stuff that we need to do. I will come over here, and I'm going to point with my Lumisphere, what do we call it yesterday? The dazzle? I think so. The Lumisphere up, the dazzle must be up. I still think that that could be the coolest techno song ever. The dazzle must be up, du du du du du. I mean, wouldn't that be cool? Anyway, so yeah, put the, I know, it's late in the day. We're gonna have the Lumisphere up, and I'm going to point this to where my camera is. That's key. Point it to where the camera is for basic metering. So I'm gonna put it under the chin, I'll take a reading, and this tells me 5.6. So now I have a choice. I can go over to my camera and just set it at 5. and take the picture, it'll be exposed properly, but is 5.6 the aperture that it should be? How do we know? When I'm setting up a portrait or some kind of a scene where I'm trying to light it, I'm gonna determine what the aperture value should be before I meter the light based on the depth of the field that I want in that photo. We talked about yesterday when I meter for a portrait. I've done a bunch of test with my lenses and I know that from nose to back of a person's head, about this much, at about 100 to 200mm with my lens, I need to be in the range of f/9 to f/11, that's where I need to be. For this, 5.6 doesn't work for me, because I want my depth of field to be about that wide. What I would need to do then is adjust the power output on my flash. So I want this to meter at f, let's say, f/10, and so f/5.6 means I need more light, more light for my flash means that I'm going to get a higher number, right? 'Cause there's more light coming in. So what I'll do, and I'm gonna do this John, so I can show people how to do it. I'll have you hold that. On the back of the flash here, on the back of the flash, there are some controls, and this is consistent. Do we have that Acute 2 pack that we can show? This is consistent across different studio lighting control. So this is a different kind of studio lighting system. This is an Acute pack, and this is something that you'll see, not just the Profoto but many many brands. That is a monolight, meaning everything is self contained in one unit, you just plug it into the wall, everything's in there. This is a pack where you plug lights into it, and you control those lights from the pack. The benefit of something like this is generally it's more powerful, you use these normally when you're getting up into the Watt seconds of 2,400 Watt seconds, 4,800 Watt seconds, the really powerful flashes almost always have a pack and a head system. The monolights like this generally are about 1,200 Watt seconds and lower. The difference is these more powerful, they're a little bit easier to use in the studio because you can have a light plugged in way up in the sky and you're adjusting it on the ground. Whereas this, if you get it way up in the sky, you have to actually climb up a ladder and change that. Except for these have remote controls for them. They're sort of fancy lights, so that's not necessarily true for all lights. But let's pretend that they're not so fancy. The thing is with almost any, with all studio strobes and with speed lights, there's always gonna be some control on there that says make the flash brighter or not as bright. It's like a volume knob on your radio. More light, less light. So that's all I'm gonna on this light over here, is I'm gonna say, we want more light. That's all I'm doing. And that's consistent across all studio strobes. What I'm gonna do here on this guy right here, this center little knob here allows me to change and put this at a higher number, and that's saying more light. And this number means something. If I go from seven to eight, that's one stop more light. From eight to nine, that's one stop more light. Nine to 10, one stop more light. This has, I believe, nine stops of control from brightest to darkest, that's a really wide range of control, and the other thing this has is I can move this in 10th stop increments. So it's highly accurate. The other pack that I showed you, this is a digital pack so I can control it in 10th stop increments meaning I can be extremely precise. With the digital pack, you don't have 10th stop increments. I think it's seven or something like that. So this is not as precise as this.
Quarter stops? Yeah, quarter stop increments. It's a little bit different. These are really really nice. What I'm gonna do here is I'm gonna put this over here, and I forgot where we started 'cause I've moved a bunch of stuff around. I know we need to be at f/9. Let's see where we are now to see if I need more or less. So I'm going to meter one more time. Metering it. (beep) (beep) Alright, we're at eight. Let me explain what I just did. We had one big blurgh, blast of light, and one (pops) small blast of light. So let me have you hold this and I'm gonna explain what's happening with that. All flashes have something called a capacitor. And the capacitor is just this device that's like a bank. It stores electricity. So it happens. The juice is coming in through this cable into the flash and that electricity is being stored in a capacitor. And it has a capacity, so it can have a full tank of gas, basically, or half of tank of gas, or quarter tank of gas. And what I did earlier is I put this to 10, and so that capacitor said, oh, you want maximum power and so the capacitor filled up all the way to the top. It had a a full tank of gas. Later, I turn the power down, but guess what, the tank is still full, right? And so until you hit, there's a test button on there, so until you hit the test button, that is gonna dump that power and then it'll fill back up to the level you'd set. So I added a 10, and it filled all the way up, and I adjusted it down to five, so I hit test, boom, it dumped out the capacitor, and then whoop, it filled it back up to the half way point or whatever it was and then it was ready to go. So anytime you change the power on your flash in your metering, you should (claps) hit the test button, or trigger the flash once to make sure the power is reset and then meter again. And that's why on a lot of the strobes, there's a big button that says test because a lot of times people will come in, they'll make a change, they'll hit test, and then they'll go. You'll see this over and over. Change, boom, dump it out, and then off to the races. So we're at eight, I think I just went a stop more. Now we're at 11 so I can take this down. (beep) Now we are at, (beep) nine. Right, that's we wanted, nine.
Nine, which is smaller than nine half.
Yes, nine, smaller than nine half. So yes, nine, the bigger the number, the brighter the light, the smaller the aperture. Alright, it all makes sense. So that's how you meter light at a very basic level. There's one other thing, let me grab that meter again. Somebody asked yesterday, when would you have the dazzle down? The light meter down? If we had, let's say, two lights or three lights, and we wanted a second light to be half as bright as this light. That's when you would have this down. You would meter this light here, say how much light is that, and then you can meter this light here. We're not metering for exposure, we're metering for the differences in power output and so having this down says, I only want this light to enter the light meter and not anything else from anywhere else. So it helps us understand the relationships between those two lights, that's how that works. Okay? So we're gonna do a lot more metering as we go. Are there any questions on basic metering so far? It's very simple at this point. When we start adding multiple lights, it might get a little bit more hairy. So now what we're gonna do is we're gonna take a picture and see how it looks to see if our exposure actually works right. So that was f/9, thank you, John. We are going to shoot our portrait. (beeps) Baboom. And what do you know? Right out of the box, we have a perfect exposure. It's perfect. This is what I love about studio lighting. It's so simple, you can just set it up, take out the meter reading, set your camera, see what the meter says, and it's perfect. And you can control the light no matter what, which is really cool. Alright, we're gonna talk about something else and that is how do we control the ambient light and eliminate that in the studio. So Lex, we're actually gonna shoot you, we're gonna have you stand right here, and I'm going to shoot this way. This is gonna be awesome. Yes, that's great. It's like that, turn to the side, maybe this way a little bit, thank you. That works, perfect. I know you love this. You're like, really? That's what we're doing? So what I'm gonna do here is we wanna try to eliminate all the light that's back this way. So what we're gonna do here, let me first take a picture with no flash. Right now, my camera is set to an aperture value of nine, ISO 100, and my shutter speed is at 200. I'm just gonna take a wide angle shot, there is no flash at all involved here. What we'll see is, we don't see any of you here, we see maybe this one little light that shows up, one little studio light. By setting my aperture value really small, and setting my shutter speed high, my ISO low, we've eliminated the light from the studio. So really the only light that the camera is seeing at this point is the light that's from our flash which means we can control it 100%. Which is great. And then we're gonna meter one more time really fast just to show you that it works. Eight, that works great. Alright, now we're gonna shoot this at eight. (shutter snaps) Kablom, oh I gotta turn on my flash. It'd turned on my lower remote control. Added that yesterday, right? (shutter snaps) (beep) There we go. Now we'll see that we see Lex showing up here, boing. It works great. Awesome, alright. You can zip back over here. Alright so we have that, and the nice thing is, if you're shooting in a studio and you have, actually you can sit down, we're gonna talk about Watt seconds and stuff. If you're shooting in a studio, and you're trying to do things like stroboscopic flash where you're doing multiple exposures, sometimes you can do things in the studio, like open the shutter up for a couple of seconds and then explode like a water balloon or something and have the flash fire to capture that scene. In that scenario, you do have to worry about the ambient light. So if you have a slow shutter speed for some reason, you need to shut everything down, but the nice thing is in most studios, you can work in an environment that's as bright as this, and you don't have to worry so much about that light spilling in because it just isn't bright enough to influence your photos. And if it is, you just turn those lights off and you're gonna be fine. So it's very very nice. Any questions on metering? Or eliminating ambient light? 'Cause we've got to get to the studio strobes science after this. We're still good on questions? We're all good? Yes, a question.
Quick question, are you using a center weighted focus? Is that how your camera,
No, on my camera, what I have is, I have a specific auto-focus point and so I'm moving it too where Lex's eyes are. I don't know how many auto-focus points this has, but it's I think in the 50s, something like that? So it's really easy to, instead of having to focus and recompose, a lot of times today I am focusing and recomposing just for speed. But yeah, I try to get that auto-focus points as close as possible to the eyes as I can. And at f/9 there's a lot of forgiveness for being slightly out of focus. Because of our circle of confusion. Yes?
So Mark, a question just came in from Lagyle who said the Sekonic site recommends metering half way between the camera and the light source. Have you heard that or do you know what that is? Or do you have any information on that?
Yes. I'm not sure where that is on the Sekonic website, and if it's there, I'll tell Mr. Braden to take it off. You won't get a proper reading if you measure half way, because the inverse square law.
No, I think it's turning the, do you turn the dome towards the light, towards the camera or halfway between?
Oh, yes. No, the dome should always be toward the camera unless you're measuring for light ratios. Then it's to the light. Or, there are exceptions to that if you're metering for highlights and shadows. In fact, you know what? Let me show you metering for highlights and shadows, because that's I think what they're talking about, is trying to figure that stuff out. I shouldn't have said that's wrong, that's wrong! Yeah, there is a situation that might work. Lex, come on out, I now wanna show how this works. So we're gonna have you just facing straightforward again and then come toward this, and we're gonna have you a little bit more, for, yeah, right there. That's good, alright. I have her extremely close to this light because she needs to exfoliate her face with heat. (strobe light beeps) No. So we're gonna do this where we have,
Close your eyes.
Yeah, close your eyeballs. So what we're gonna do here, is we're going to meter for the highlights. And there is, I wanna meter for the bright part of Lex's face. So what I'm gonna do is I'm gonna point this to the light, and point this to the light (beeps). So I'm metering the light that's falling on this side of her face, and I'm ignoring the light that's over here. And that gives me a value of f/10, and I will shoot this very quickly. This is giving me a value of f/10. How is that heat from the light? You're pretty good? You like it? Yeah. You like it. (shutter snaps) F/10. Okay, so now, what we're going to do, and you can see that now we have a proper exposure for the highlights and the shadows have just fallen out. Right, we don't care about those shadows. Now meter straight to me (beeps), and it's eight. Now what happens when we have the Lumisphere coming this way, is it's taking into account the shadows and the highlights. In this situation, there's a good chance we're gonna have an over exposed side of her face. I'm going to go in here, now we're at eight. (shutter snaps) (strobe light beeps) Taking that photo. We still have, we have a little bit more of those shadows falling up if we did, perhaps this, that would wrap around a little bit, let's measure that. So we can get a little bit more. (beeps) Yeah so that's still at eight. (beeps)
So still eight and ten. You'll see that on this first shot here, it's very difficult to see on this TV here, but you can see it on the computer monitor, the shadows have more detail in the second shot than the first shot. What I'm gonna do here is I'm gonna, I moved this horizontally so we have a little bit more wrap around and we'll try it again, just see if it can be a little bit clearer on the scene. Here is the first shot, this is f/10, metering for highlights. This is the second shot, f/8, metering for both. Let's take a peek and see if that's a little bit more clear. This is something that you do in fine art photography all the time, is metering for highlights or shadows. Let's see if we can compare those two shots side by side. You can clearly see on the second shot, we have more shadow detail than the first shot. That's one of the situations that you would perhaps meter a little bit differently. Right, thank you. Okay, what other questions do we have? Any other questions?
Yeah, I got one from Kathy R.. What if you cannot eliminate the ambient light but it still spills in to your image? Should you just find a way to block that ambient light in any way you can? Do you use flags?
You can. There, in fact, we're doing that here in the studio. I don't know if you guys can show these windows here. I wanted it to be really dark in here. We couldn't eliminate the ambient light coming through these windows, and so the CreativeLive staff came in here and they put big sheets of black paper all over these, yeah so they did a bunch of work to gaff tape and do a bunch of things to eliminate the ambient light. So yeah, that's basically using a flag. But unless the light is pretty darn bright witH a studio strobe, you're usually gonna not have an issue with it. But yeah, if you can't eliminate the ambient light all together, then flags, whatever you possible can use. The other thing that you can use are those, those form of black panels that we saw, they can absorb the light, and you can sort of build a little cocoon of darkness, curtains. I've seen a lot of people, instead of using a seamless paper like this, you can get like a black, muslin kind of, curtain that you can put up. A couple of those you can rent very very affordably, and you can sort of build a box of dark. You can buy this cloth called duvetyn at any fabrics store, it's really really dark, heavy fabric, and you can just sew a little pocket on the top of that, put a pole through it. There's a bunch of ways that you can sort of build out a dark room.