There are several things, that come into play when shooting with Canon Dslrs concerning Color Grading:
Dynamic range can considered to be the ratio between the darkest and brightest Values that can be reproduced by the camera. The human eye can be considered one of the most fleble means for reproducing a great range of dynamic range, due to it´s flexibility. Traditional film has long be thought of the best medium to reproduce great dynamic range, but electronic cameras have caught up quite a lot in this aspect.
I would recommend to have a look at www.zacuto.com/shootout for this topic., where Kodak and Fuji film stock are compared with the Red One, HPX3000, HVX200, EX3, HPX170, XH-A1, 5D-MKII, and the Nikon D90.
As you can see in this Comparison the camera performs surprisingly well, holding up well against mighty old film. Avoiding heavy over exposure, you can get a lot out of the canon 5d. One crucial thing is that you stay away from the default settings of the camera and alter the “picture style” of the camera into a “flat profile” similar to a logarithmic file that preserves the dynamic range of the image. There are heavy discussions about this, generally i think
“Marvels Cine Picture Style”: marvelsfilm.wordpress.com/marvels-cine-canon/
“Cinestyle” by Techicolor www.technicolor.com/en/hi/cinema/filmmaking/digital-printer-lights/cinestyle/cinestyle-downloads
From what I read, this seems to be the best way of getting good dynamic range, also using the provided lut, in order to get the most out of the camera.
They all follow an important issue of getting all the latitude out of the sensor, but in general i thought that the recommended settings of Phillip Bloom
Picture profile Neutral,:
-sharpness all the way down
-contrast all the way down
- saturation down one notch
get you into a good starting position, i only would use higher sharpness settings in the future, because you would definitely have to sharpen the image, but then it can be done in post as well, so it´s basically up to you.
This is one of the biggest drawbacks of the camera. It´s native format is based on h264, which is visually good, when you get into the guts of the footage you definitely find limitations there. Video clips are recorded as Quicktime MOV files with H.264/MPEG-4 (Base Profile @ L5) compressed video and uncompressed PCM audio at 48 kHz. HD bitrate is approximately 38 Megabits per second (4.8MB/sec) and SD bitrate is approximately 17 Megabits per second (2.2MB/sec) (en.wikipedia.org/wiki/Canon_EOS_5D_Mark_II). As far as i know there is no way of getting a truly uncompressed format out of the camera, when you record the HDMI output of the camera uncompressed, I read that the image quality is not much better than what you get by the cameras direct h264 output, but i could not confirm that. If you record a video the HDMI output drops down to 480p.
Both for Grading and Keying this is an important issue. The camera records in 4:2:0 meaning that it uses every pixel of luma values and the colors get averaged in 4 pixel blocks. (more information about this at 5dfilmmaking.com/tut_444.htm).
The consequences are grave, but while grading i found that the material holds up quite well , as long as you don´t dig too deep into the material. Especially when doing color keys inside areas where there is not much chromatic latitude it will simply fall apart. (see image). I thought that it´s enough to improve the image and get a certain look onto your images, but comparing to film i thought it hard to push colors around freely. Basically you can enhance what you already captured, but it´s hard to completely alternate the look of your footage into a completely different direction.
Unfortunately i could not test keying capabilities of the camera, but looking at the Color subsampling Issues mentioned above i seriously doubt that you can get excellent keying with what the camera provides.
Getting the footage into Assimilate Scratch i was surprised at how much you can get out of the footage. Although compression and color sampling (see previous chapters) are quite an issue there´s definitely room for creative grading. Even over bright Skies and dark areas (noises in the low levels can be a heavy issue there), but as the camera is excellent with it´s low light capabilities this can be dealt with the right camera settings.