In still image files shot with the Canon 7D and other DSLRs, we have the luxury of using RAW format to capture each frame and get a tremendous amount of latitude (exposure and color range in over/under-exposed shots) out of those files in post production. Unfortunately, when it comes to video capture, DSLRs like the Canon 7D spit out a highly compressed file that has nowhere near the amount of latitude you get from a RAW still image file.
While the below video comparison may seem silly in some respects for comparing a $1500 camera to a $65,000+ (depending on the configuration) camera, it is also very useful to those new to HDSLR video – as a way to demonstrate (1) just how limited these cameras are when it comes to capturing video, and (2) just how much more important a perfect exposure is when recording video.
Another point to consider, which was raised by a couple of comments in a recent post about Magic Lantern firmware . . .
The new Magic Lantern firmware increases the bit rate for the 5D Mark II’s captured video (sorry, there’s no Magic Lantern for the 7D yet). A higher bit rate means more information captured by the camera and less compression, which allows you to push the footage further in post production. Admittedly, the sample video in that post doesn’t do much to help us see this benefit, but when you hear video geeks talking about 24Mbps is better than 17Mbps, this is what they’re talking about.
Coming full circle now, the comparison of the Canon 7D and ARRI Alexa above demonstrates the extreme ends of this bit rate discussion (i.e., the 7D doesn’t have much latitude with its highly compressed codec, while the Alexa has a ridiculous amount of latitude with its Pro res 4:4:4 capture).
[via PVC Problog]