Exposure tools: Histograms, false color, zebras, waveforms » Filmmaking basics 5/5
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Exposure tools: Histograms, false color, zebras, waveforms » Filmmaking basics 5/5

February 28, 2020

Hey y’all, It’s Mary Betsy of MaryBetsy.com and welcome to the third video in my series on exposure. If you haven’t watched the first two videos, then you can find links to those in the description below. But in this video we’re gonna be looking at what tools you have inside your camera and inside external monitors to help you measure exposure and nail it every time. By the way, I didn’t know about all these tools for like the longest time even though I was working as a filmmaker. I’d always just eyeball my camera’s LCD screen to set the exposure which you can totally do, but sometimes it can be kind of hard. You feel like you’re just guessing especially if you’re shooting outdoors and sunlight and there’s a glare on your screen and so that is where using these exposure tools can really come in handy and help save your behind. Aight, let’s jump in! Okay, so exposure tool number one is a histogram and a histogram is just this fancy name for a bar chart that shows how often something happens. So teachers will often use a histogram to show the grading curve and to see how many students got different grades and most histograms look something like this where we see the biggest number in the middle and then only a few students on either end who got a really low or a really high score. Now the histogram on your camera obviously doesn’t measure grades from zero to a hundred but it measures brightness from zero to a hundred and it’s not measuring how many students are at different levels. It’s measuring how many pixels are at different levels of brightness So the very left edge of the histogram shows how many pixels are pure black. That shows how many pixels are in the shadows, the middle shows how many pixels are in the mid-tones, the right side shows how many pixels are in highlights, and the very right edge shows how many pixels are pure white. So here’s the histogram for this shot and you’ll see that we have a lot of pixels on the right side because we’ve got this white piece of paper. Now if we cover up that white piece of paper with a dark one then you can see how the histogram shifts. So all those pixels that were white are now gone and there are more dark pixels on the left side of histogram. So, how can you use a histogram to make sure that your exposure is right? Well, if your shot is too light then your histogram is gonna be squished over on the right side. Or if your shot is too dark, then your histogram is gonna be smushed over on the left side. And if your shot is way too dark or too light then it’s gonna look like the histogram is clipped off on the edge. And you definitely don’t want that because that means you’ve got too much black or too much white in your shot and that you’re cutting off details. And so most times you want to see a histogram that’s balanced in the middle and that tapers off on each side. So that is how a histogram works and you can use that baby to make sure that your exposure is on point. Well, most times that is. There are some situations where a histogram is not the most helpful tool. So let’s take a look at one of those. So in this shot if I try to get the exposure right for Myles and then I look at my histogram to see if my light is right, then my histogram is actually not very helpful because it’s clipped off on the right side because we’ve intentionally made these windows so bright. So if our histogram is not very helpful here then how can we tell if our exposure on Myles is right? Well, this is we’re using other exposure tools can be really helpful. We’re gonna talk about those in a second but first I just wanna let you know that not every camera has the tools we’re about to talk about but you can get them if you get an external monitor or if you’re a Canon user you might consider magic lantern software to get these tools. Aight, let’s jump into the next tool. Exposure tool number two is false color. So false color is a tool that shows colors on top of your image to let you know how bright or dark those areas are. So imagine you took your histogram and instead of wanting to know how many pixels have a certain brightness you want to know where those pixels are located on your image? So you could assign a different color to each brightness level and then plot that on your image and you’d have something that looks like a heat map, you know those weather maps that show you where different temperatures are but in the case of false color you’re seeing where different brightness levels are. These brightness levels are measured in units called IRE which stands for Institute of Radio Engineers who are the peeps that came up with it way back in the day. Now every monitor displays false color a little differently but in general cooler colors show you where your darker tones are and warmer colors show you where your lighter tones are and you’ll see the color fuchsia where your IRE level is zero, so where you have no brightness. And that’s where the shot has completely black pixels. On the other side you’ll see the color red where the IRE is 100 or where you have areas that are the brightest in your shot. And that’s where the pixels are totally white. And so false color uses these bright bold colors of red and fuchsia to let you know very quickly that your shot might be too bright or too dark and that you need to adjust your exposure. And I think that the false color tool is super helpful when you’re trying to expose skin tones. So let’s go back to our example with Myles in front of the bright windows. Again, our histogram is not very helpful because it’s showing us there’s too much white in the shot. We already know that because the windows are really bright but if we use our false color tool then we can see whether those areas that are too bright show up on Myles’ face or not. The problem is that I can adjust the exposure to a few different levels and still not see any red on Myles’ face or not see any white pixels on his face. And so how do I know which exposure is the right one? Well when it comes to skin tones you’re looking for highlights to be between 30 and 80 IRE depending on the color of the skin. And since Myles has really light skin, we’re gonna be looking for highlights around 80 IRE which means we’re looking for the highlights to be this lime green. So I’m gonna adjust my exposure on Myles until I see just a little bit of that green color on the highlights of his face. And now we can feel good that our exposure is right on our subject myles. So that is how the false color tool works and hopefully understand now why it’s so gangster because you can be so precise in setting the exposure exactly how you want where you want it. Exposure tool number three is zebras. So what are zebras? You don’t know what I am? Zebras are these black and white stripes that show up on your image to let you know which areas have pixels at a certain brightness level? So it’s kind of like if you took one color from your false color map and you put stripes on it then you’d have zebras. So if your camera has a zebra function you might need to go into the menu first and turn it on so that it shows up and then you can select an IRE level or a brightness level for the stripes to show up on. So if I set the zebra level to 100 IRE, then it’s gonna show me where all the white pixels are in my shot. So then if we set our exposure to be way too bright, we’re gonna have too many white pixels and so there’s gonna be zebra stripes all over our image, which is not a situation that we want. So what I’ll do if my zebras are set at a hundred is that I will dial them down just until the point that I don’t see any zebras on my subject anymore. Now if my zebras are set to 100 and I’m starting a shot and I don’t see any zebras on my image at all then I know that my shop might be too dark. So I’ll adjust my exposure to brighten it up until I see the zebras again and then I’ll dial it back one notch just until they don’t show up on my subject. And that’s how I use zebras to set the exposure. And what’s cool about zebras is that your histogram might look way out of whack because you might have sections of your image that are too bright or too dark but zebras are showing you the exposure in a certain area. So you can really hone in on your subject and make sure that they’re exposed right. And just as a reminder, zebra stripes are just something that your monitor is showing you. So they’re not going to show up and actually be recorded onto your video footage because that wouldn’t be cute. Now, let’s go back to our example with Myles in front of the bright windows. And if we’ve got our zebras set to 100 then we can see those stripes all of over windows. That’s okay because we know there’s a lot of white pixels there. We’re most concerned, though, with the exposure on Myles’ skin which means we definitely don’t want to see any zebras set to 100 on his face. Because, his face shouldn’t have any white pixels or it would be too bright. So I’ll adjust the exposure on Myles until there are no zebras on his face. But we can use zebras to be even more precise because remember when it comes to skin tones we’re looking for highlights on skin tones to be between 30 and 80 IRE. And since Myles has really light skin we’re looking for highlights around 80 IRE. And so we can change our zebras setting from 100 where it’s gonna show us where all the white pixels are and we can notch that down to 80 so that now the zebra stripes are going to show up only on areas that have a brightness level of 80 IRE which is what we want the highlights on Myles’ skin to be. So now if we go back to our shot with our zebras set to 80 I can just adjust the exposure until I see a small area of zebra stripes on Myles’ face where the highlights should be and now I know that my exposure on him is gonna look good. Okay, so now, you know all about zebras. The fourth and final exposure tool we’re going to talk about is the waveform. So a waveform is a graph that has a wavy form and I think that this tool is like the hardest to wrap your head around in the beginning but a lot of filmmakers love it. It’s like their favorite. So let me see if I can explain this for you. So waveforms show you brightness levels just like a histogram. But instead of showing you dark to light on the horizontal axis, they show you dark to light on the vertical axis. So black is at the bottom and white is at the top. So you can see that if I adjust the exposure to be darker the waveform goes lower and If I adjust the exposure to be brighter the waveform goes higher and so that means that if our exposure is too bright then our waveform is gonna be clipped off at the top and if our shot is too dark or if it’s underexposed then our waveform is gonna be crushed down at the bottom. Now the horizontal axis of the waveform lines up with the horizontal axis of your shot. And so the left side of the waveform is showing you what’s happening on the left side of your image. And so if we look at the left side of this image It’s almost completely black which is why if we look at the left side of the waveform everything’s down at the bottom. All of the pixels are down at zero IRE. If we move to the middle of the waveform that is showing us what’s going on in the middle of this shot. And so in The middle of this shot we’ve got some white pixels from the bubbles in the water. We’ve got these lemons that have brighter mid-tones and we’ve also got the black background and so if you look at the middle of the waveform you’ve got some pixels up near the top that are really bright, you’ve got some pixels in the middle for those mid-tones, and then of course you’ve got pixels on the bottom because there’s a black background. And then if we move to the right of the waveform that’s showing us what’s going on on the right side of this picture. And there’s not quite as many bright areas on the right side of this shot and so you’ll see that the waveform on the right side is more toward the bottom. Okay, if you’re like, “Mary, I don’t understand what you just said,” then let me show you how you can use a waveform to get the right exposure in this next scenario and see if it makes a little more sense. So if we go back to our shot of Myles and we look at the right side of the shot it’s got a lot of bright pixels and so if we look at the right side of the waveform we can see that it’s got a lot of pixels at the top which normally would stress us out and let us know that the shot is overexposed, but we don’t care that the windows are too bright. We’re trying to get the exposure right on Myles. And so if we look at this section of the waveform where Myles’ skin is, and more specifically, if we focus in these areas, then we know that the highest or the brightest part of this area of the waveform should be around 80 IRE. And so we can adjust our exposure until this lines up. And now we can feel good that our exposure is right on our subject Myles. So hopefully that gives you an idea how useful waveforms can be. So that’s the last tool we’re gonna talk about. We talked about histograms, false color, zebras, and waveforms. And I think the trick to using exposure tools is to not totally rely just on what the camera is telling you in that graph, but also not totally trust yourself just eyeballing the LCD. But if you can check both then you’re gonna have the most information about how to set your exposure right. And I also think you want to use the tool that you actually find helpful. You don’t have to use them all. I personally tend to shoot a lot of work that’s just documentary. And so I don’t have a lot of time to always be popping on an external monitor on every single one of my camera bodies and lenses. And so I just use the tools that are built into my Sony. So I use the histogram and the zebras a lot. But if I’m shooting an interview and I have a little more time to set up I will definitely pop on an external monitor so that I can check the false color and make sure that I nailed the exposure on skin tones. And as far as waveforms, I actually use those when I’m editing to make sure that I’m correcting my exposure properly in post. But we’ll talk more about that in the editing section. Alright, so that is it for this lesson on exposure and this is actually a preview lesson from my filmmaking course that teaches you how to make professional videos and you can learn more about that at MaryBetsy.com or you can just download some free filmmaking tools like this story template or this cheat sheet on frame rates at MaryBetsy.com/free-tools. And if you’re interested in more filmmaking tutorials like this one then hit the subscribe button and the notification bell below and you’ll get hit up when my next video comes out. And as always if you have any questions at all about what was covered in this video please hit me up in the comments below. I read them all and answer them all and I would love to hear from you. Alright, y’all thanks for watching. Bye!

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  1. Thank you for sharing this so valuable information!
    For me (a begginer) this was the most challenging part of filmmaking but with this vídeo i have a better idea of how it works!
    Thanks a lot, keep up the good work!☝

  2. I had to trawl through hours and hours of ego filled tutorials until I found yours to help explain this topic. No nonsense, no distractions and no problem for me. I subscribed and you're a born teacher. Greetings from Spain.

  3. Excellent video. First glance on your content and very pleased how the info was structured and delivered without a waste of second. Keep it up pal! U got my subs. And hope we could do a collab in future too, never know 🙂

  4. Mary Betsy: I don’t quite know the words to say my thanks and gratefulness, your lesson is just amazing. This was a pleasure to watch and so much good information to use. I subbed

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