I did a compression test on our Epic today, and I wanted to share my results, and see if this seemed right to all of you.
What I found, in short, was that on difficult scenes, 3:1 was great, 5:1 was good enough, and after that blocky compression started to appear.
Here is a link to download and below is a description of the shoot:
Scene: I shot a streetscape filled with trees, including some foreground bark, and a more isolated shot of the trees. I was hoping for a sunny day, because I read that some others had compression trouble in high contrast scenes. However, from seeing the results, a slightly overcast day worked fine.
Lens: I used a Zeiss cp.2 35mm lens. The aperture remained small (about f/15 to f/16) because I wanted a sharp image that would really test the compression. I did not use an ND filter.
Camera Settings: The ISO was 640. The frame size was 4K HD (this is just because it's how we intend to shoot an upcoming project). The framerate was 29.97 and I used a 180 degree shutter angle. All other settings that I can think of were set to their defaults (except white balance).
Notes: All of the jpegs in the link above were made from the raw tiffs out of RedCine X Pro, and I've verified that there is no visible difference between the jpegs and tiffs. I applied no post-processing as you will see, except I've blurred some signs and license plates in the 1st shot (sorry, I just wanted to be safe). I want you to know also that even though the jpegs are all the first frame of the video, I played all of them and the frames in the rest of each shot look the same.
The compression really showed the in bark. I know this is a rough test to put a camera through, but we intend to shoot some scenes like this in the future.
I would love to hear any of your analysis. Are these results expected? Did I do something wrong in my test?
Thank you in advance!