Discover The Importance Of Capturing Video Footage In RAW With Our Understanding RAW Video Formats Tutorial
THE RULESMost of the camera manufacturers lay out some rules for exposing Log on their cameras. This means that they define how to expose for middle gray (18% reflectance) and white (90% reflectance) to maximize the dynamic range in your image. You can usually find these numbers buried in white papers filled with graphs and charts. Panasonic recently published one for the VariCam 35. Here are their exposure rules for V-Log (see the chart below).
They define where black, middle gray and white all fall in terms of both IRE % on a waveform and code values. As you can see, they say that their 18% gray reference should fall at 42% on a waveform, and a 90% white card falls at 61% on a waveform. It turns out that those numbers are pretty similar to other Log curves. Here they are compared (see the chart below).
From LogC to V-Log, most Log curves are about the same, which makes sense because they’re all designed to be similar to the original Log Cineon curve used by film scanners. This means that, for the most part, if we know how to expose Log on one camera, we can pretty much expose it on any of these cameras. And with all of the cameras noted above, exposing correctly for Log also means exposing correctly for RAW. That makes it pretty easy.
Now that we know the “rules,” let’s talk about how we can apply them with some exposure tools.