I also think that your lens is the problem. Maybe it needs some adjustment. You can check if that is true by the following experiment. Select a well lit wide angle landscape scene with a lot of fine detail, put your camera on a tripod, focus precisely using the manual focus ring at magnified Lifeview, stop the lens down to say F8 and film some footage at your 4128x2230 resolution. Then, without moving the camera and touching anything on the lens, take a CR2 still of the same scene. Then crop the center part of the CR2 file to about 4128x2230 size, export a frame grab from your footage using MLVApp and compare both frames at 100% magnification using a viewing software such as FastStone Image Viewer (free, google it). If there is no noticeable difference in sharpness, then obviously, the lens is to blame. In that case, repeat the same experiment with another sharp lens and compare the results. The 5DIII provides extremely sharp footage in the above anamorphic mode.