Sorry if you've already seen this on the Canon EOS forum, but I've yet to find anyone with a similar problem - therefor, no solution.
I'm getting ready to return my second 5D Mark lll. I purchased the first just three weeks ago and returned it to the store after noticing subtle vertical noisy streaks in in the picture. Streaks were most evident on pans and in dark areas or in saturated colors, but could be seen faintly when the camera was stationary as well. Stills looked beautiful, but 4:2:2 video straight out of the camera via HDMI or 4:2:0 recorded internally was unacceptable.
My replacement 5D shows the identical problem AND has a very ugly dead pixel that shows up a few minutes after the camera is turned on. I've tried using more expensive glass than the 24-105 kit lens, experimented with every picture profile, checked to see that I'm running the current Canon firmware, etc., etc. Is it just a coincidence that I got two bad cameras in a row? I've seen lots of footage from other people's Mark lls and never thought I was viewing video through gauzy vertical lines. The pixel issue is just the icing on the cake. I can't shoot anything but white people and wardrobe against a white cyc with this thing.
Here's a still showing the streaks in my first camera. The second looks the same with the addition of the bright red pixel. Moving video is easier to see, but, unless your monitor has crushed blacks, you'll detect the streaks in the wall on the left as well as in the countertop. Thanks, in advance, for any thoughts or feedback.
It must be a bad run. I've never seen this on my Mark iii. Strange. Is it happening at a high ISO? What are your settings. I shoot 1920x1080 @ 23.976fps with a shutter speed of 1/50. ISO in 160 multiples (160, 320, 640, 1250). The 1250 because there is no 1280.
I picked up my third camera a couple of days ago. The picture quality is far superior to the first two. I made sure I got one that had a very different serial number hoping to avoid another camera that may have come from the factory at the same time. Looks like Canon may have shipped a faulty batch.