This is a comparison we have had requests to see. Since we had seen the individual tests during the Camera Comparison Seminar earlier this year we were aware of where these cameras fall but since the EOS 1DC is such a different EOS Cinema camera there have been questions as to how these two compare if you down-res the 4:2:2 4K image to HD from the 1DC and compare it to the C300. Two things to keep in mind when you watch this comparison
1- If you record in the S35 or Full frame HD mode of the 1DC it will do a very respectable HD recording but it will be a 4:2:0 color sample so even though it is a very clean recording because of the higher bit rate it will not have as much color information as the C300.
2-If you record in the 4K mode of the 1DC it can be used as a HD signal either by a realtime output of the HDMI connector or down converted in software (how this comparison was done). Either way because it is essentially a oversampled HD signal at 4:2:2 it is very comparable to the C300 but with the added advantages of an archival 4K master, crop, zoom, HD image stabilization in post without any HD softening and high res stills. Also not explored in this comparison but you will notice a slight advantage in terms of low light noise, sensitivity and dynamic range of the 1DC as the photo sites are actually a little larger than the C-300. (APS-H vs. S35).
As always. we recommend you also do your own comparisons and decide which camera is best for your project. One area we have had a lot of success with the 1DC is projects that need to stay on tight shooting schedules and require high maneuverability. Also projects that may benefit from a single camera that also shoots high res stills or stills that can be pulled from the 4K motion files. One thing we did not mention in the video is that it is also possible to achieve three different crop ratios with the same lens. We had a local cinematographer on set that needed a wider angle and he simple went to a full frame mode for that shot and was able to incorporate it into his project.
In summary we have found the 1DC, despite its DSLR like appearance, to be a very viable option for some projects and certainly worth consideration even if all you really need for a project is just HD as it make some of the best HD images we have yet to see.