There’s a great tutorial over at Vimeo on controlling the dynamic range of digital SLRs when capturing video. It turns out that the video mode of digital SLRs is tuned like a typical JPEG mode: To get a contrasty, “finished” look right away. But like JPEGs, this means a lot of tonal and color information is tossed out before the capture is saved, which can be limiting if you need a look that’s different than what the camera gives you. If highlights are blown or shadows are plugged, you may be left with nothing to work with at the high or low end when you try to adjust the image quality.
The technique covered in the video linked below involves using Canon Picture Styles (presets for how the camera processes images) to dial down the contrast and color in an attempt to squeeze as many of the original scene’s tones as possible into the range the sensor can capture. A file captured this way looks flat and lacks contrast, and isn’t something you would show as finished. But that’s because, as with raw capture or like Ansel Adams shooting film, we are at a step in the process where we’re not trying to create a perfect picture at the moment of capture, we’re trying to capture enough of the right data from which we can produce a perfect picture in post-processing. That’s an important difference.
It’s also important to understand that this capture technique isn’t quite as good as actually capturing video in raw format, but video cameras that do are pretty rare and I think most of them are expensive and called RED. This technique is about doing the best you can with the non-raw capture you have.
This capture technique is often called increasing or maximizing the dynamic range, but I prefer to call it optimizing. You’re not making the sensor capture more tones, you’re rearranging the tones you’ve captured before they’re recorded. I suppose you could call it maximizing the available dynamic range.
Here’s the URL to the video:
While the video talks about the technique in terms of the Canon 7D, Canon Picture Styles can be used with the 5DMkII and others. And the principle can be applied to other brands of cameras that give you control over the image quality of the video.
(Update: [May 2011] You might want to try the new Cinestyle picture style by Technicolor and Canon, a more “official” version of the picture styles described in this post.)