Whether you’re talking hue, saturation, exposure, or white balance, modern cameras can capture video in extremely flexible codecs and color spaces that give you a lot of headroom to tweak settings during post-production. But that freedom comes with a warning: if the highlights or the shadows are clipped, there’s no bringing back that information, as the camera simply didn’t capture it. That means you can have perfectly framed and colored footage that still turns out unusable because of poor exposure settings during the shoot.
Luckily, modern cameras have implemented an array of tools to help you avoid that exact scenario, letting you nail your exposure in camera, or at least get close enough where the shot can be salvaged in the edit. Read on as we go over the four most frequently used exposure tools.
Histogram
Histograms have become a nearly universal feature on video and still cameras, and they’re usually people’s first stop on the exposure monitoring train. A histogram is a graph that displays the distribution of luminance in the image—basically showing how many pixels are underexposed, how many are overexposed, and where the rest of them land on a scale from 0 (pure black) to 100 (pure white). The X-axis is exposure/IRE values, and the Y-axis is how many pixels sit at that level. The histogram is a great tool for overall judgement, but sometimes it’s not specific enough, as there will be shots that you want to be way darker or lighter than the rest, maybe even with areas that are clipping.
The histogram will adjust in real time as you move the camera or change settings, and the goal is typically to create an image with an exposure range where most pixels exist in the middle third of the graph and taper off on each side with zero pixels all the way to the left (clipped shadows), or all the way to the right (clipped highlights).
Histogram issues usually happen when scenes are shot outside. The sky will skew heavily right on the exposure index, with subjects in the frame more to the left because they are darker than the bright background. This can throw you off, as your histogram will have a big peak to the right and a little blip to the left. That blip is your subject, and it’s what’s most important in the frame.
Your overall exposure should be built around getting your subject where you want it in the IRE range, but seeing the peak on the right can mislead you into thinking everything is too bright. You bring down your exposure, your background sky gets to the middle, but now your subject is far to the left, massively under-exposed. No good. An inverse issue can happen inside, when you get thrown off by dark interior backgrounds skewing to the left, raising your exposure to compensate and inadvertently overexposing your subject.
Always identify the most important part of your image, figure out where it is falling on the histogram, and adjust your exposure so it’s in the luminance range you desire. If you can prevent clipping in the background by adding or subtracting light, great. If not, a properly exposed subject still comes first.
Zebra Stripes
Zebra stripes are also becoming a ubiquitous tool on modern cameras. Though rarely turned on by default, you should be able to find them by poking around your settings. They act as an overlay, creating “stripes” or a crosshatch pattern on parts of your image where the brightness level exceeds an IRE measurement that you’ve specified in your settings menu.
Let’s say you set your IRE to 100, stripes will show up over any parts of the image where the brightness exceeds 100 IRE (and clips). This can be more helpful than a histogram because not only will you know if your highlights are clipping, but you’ll also instantly see where in the image that clipping’s happening. Many filmmakers will set their zebra stripe IRE closer to 90 or 95 so they can avoid getting anywhere near blown out highlights.
Some people will even set their zebra stripe IRE lower, maybe to 70 or 80%, as those are good IRE ranges for skin tones. Then they’ll adjust exposure until the stripes show up on all their skin tones. Most cameras don’t let you use two different IRE settings at once, so the stripes either help with clipping or skin tone exposure, but not at the same time.
Like the histogram, zebra stripes are super helpful, but not the be all end all of exposure. Sometimes an overexposed part of the image is necessary to achieve proper exposure in the areas that matter most, and sometimes overexposure is an intentional choice, especially when using bright lights or embracing flares. The key to both tools is the knowledge they give you regarding how your image is coming together. You can’t trust your eye to know when things are over or underexposed, especially when ambient light interferes with your camera’s display. These tools use math and science to give you a deeper, more accurate perspective on the image.
Waveforms
Your waveform monitor is like a histogram in that it maps exposure levels from 0 to 100 IRE, but often more useful because it shows where in the frame those IRE levels are happening from left to right. So, if have a bright window on the left side of the frame, the left side of the waveform will be high, and if you have dark shadows on the right side, the right side of the waveform will be low.
With a waveform, the goal is to have nothing hit the bottom of the chart (0 IRE) and nothing hit the top (100 IRE), as that means you’re not clipping. Sure, it’s only charting the image horizontally and not vertically, but if you know the exposure for a horizontal slice, it should be easy to guess what within that slice is most affecting the waveform.
When reading a waveform, note how dense the wave is at key luminance levels. Brighter, more packed together areas mean more pixels from that horizonal reading are sitting at that specific luminance level. Lighter, less dense parts of the wave mean only small bits from the horizontal slice sit in that IRE range. Not all waveforms are created equal though, as you’ll want to know what the waveform’s pixel ratio is. Pixel ratio is how many pixels in the image are being judged by the waveform. So, a 1:1 ratio is mapping everything, while something like a 1:4 or 1:8 ratio is only mapping ¼ or 1/8 of your pixels. Waveforms with smaller ratios aren’t the end of the world, but they are a less accurate reading.
Certain monitors will even be able to create an RGB Waveform Parade, a special waveform that breaks down the three individual color values and shows where each of those colors are sitting in the exposure range. Those take a bit more know-how to read and utilize but are worth looking into if you’re curious.
False Color
False color is the most advanced of these four exposure tools and still a rare find within cameras, but it is increasingly common in production and on-camera monitors. What it does is create an overlay on top of your image that maps the exact exposure rating pixel by pixel, replacing the real colors of the image with colors that correspond to exposure. Turning false color on should add a chart to the bottom or side of the frame that maps all the IRE values to these colors, typically blue tones on the low end, greens in the middle, and oranges on the high, with pink for clipped underexposure and red for clipped overexposure. You can now see in exact detail what IRE every part of your frame is coming in at. Again, each shot will have its own style, and you may want parts sitting extremely high or low on the IRE range, maybe even clipping, but false color is the best way to know exactly where those points are at.
False color is also incredibly helpful for getting properly exposed skin tones. Like we mentioned when discussing zebra stripes, most filmmakers want their skin tones sitting around 70-80 IRE. False color clearly shows you exactly what parts of the image fall within that range, so you can focus in on facial readings and change your exposure settings accordingly.
Many filmmakers also like exact lighting ratios, where certain parts of the image are double or triple the IRE of other parts to create an alternating light dark light dark pattern. By specifying IRE values for every part of the image, not just areas or slices like the previous tools, false color is the easiest and most accurate way to know what your exposure ratios are and how much you need to change exposures to get the ratios you desire. Check out examples online of different lighting ratios, then experiment in real life to see what ratios you might want to utilize in your next shoot.
Conclusion
Even with these exposure tools, the bulk of the work still falls on you. They’re simply graphs and markings that express information, it’s up to the filmmaker to interpret the findings and adjust exposure accordingly. The secret is to have all this know-how in your back pocket, ready to pull out when you’re faced with dark shadows, bright sunlight, and other potential stressors.
Now that you’re more knowledgeable about these four instruments, you’re well on your way to beautiful images with no unintentional clipping in sight. A good step for further research is looking into what makes up a “stop of light” and how that equates to aperture, shutter speed, ISO, and IRE. But that’s a topic for another day.
Which of these readings do you think is the most helpful? What are your methods for good exposure? Let us know in the comments section below!
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