I bought a Canon 5D mkii late last year, and almost immediately I saw that there were dropped frames/freezing (only just noticeable) while filming in HD. At first I just thought it may just appear that way in camera, but once loaded up on the computer in Quicktime, they wouldn't be there. There were however similar issues once on the computer, but I took that as just being the size of the files, and that one day in the future all my HD stuff would play fine. It wasn't until a few months later that I finally noticed that the glitches were being seen at the exact same point while filming, on replay on the back of the camera, on my HD TV, and on my HD laptop. Before calling Canon or the shop and being told the usual "try turning it off for 5 minutes, then back on again" I decided to explore all the avenues I could to suss out if it was firmware, in camera settings, a lens issue, the image stabiliser, or that my CF cards weren't fast enough. So, I updated the firmware, turned off image the image stabiliser; these didn't fix it. Now my CF cards. I have 3 that I bought off eBay several years ago, that were cheap so obviously knock-offs, but I knew not to use these. Instead I used the 2 Compact Flash Cards that I won in competitions in photography magazines, so I knew they were legit. You could also feel the difference in speed. These were 2 and 4GB, so seeing how this camera chews up memory, I bought a 32GB Lexar CF. All of these cards produced the same results. I then looked back at the footage I had shot using a tele-zoom 100-400mm lens, and none of it had any of these dropped frames, so for the moment the 24-105mm looked like the culprit. I noticed that this 24-105mm needed some lens correction in Camera, which the camera did automatically if you chose to do so; I turned it off, everything seemed fine, but it did eventually happen again. I then remembered I took some macro footage of a spider about a week after buying the camera, with a Sigma 70mm EX lens - the second video clip contained the dropped frames, so it was now clear it wasn't the lenses. Now I had explored all the possible solutions, I called Canon and asked them what needed to be done. They were saying it needed to be sent in for repairs, which would mean 2 things - 1) I would be without my camera for anything up to 2 weeks, 2) It would almost certainly cost about £40-£50 in special delivery costs. I then called Jacob's photography in Canon St London where I bought it, and they told me to bring it in and they would exchange it once they saw the issue for themselves. I brought my laptop just in case they wanted to see all the examples, but it wasn't necessary, they were happy with the 2 clips stored in the camera. Before I left the shop with my new camera, I put the battery in and stood by the window to film the traffic outside as a test; there didn't appear to be a problem (as yet). Later that night I plugged it into my HD TV to do some tests, and everything seemed fine, but as I panned the camera I little white dot caught my eye. Now, I remember seeing 2 of these little white dots while doing close ups of some family members with my previous camera, but just assumed it was dust and needed cleaning. For this to appear immediately after the exchange was not good. I had a feeling that this might be a "hot pixel", so I did some looking about on line, and sure enough many others had been experiencing this with HD SLRs. I tried all the tips like sensor cleaning and sensor re-mapping, but the whitish pixel remained. The camera will have to go back yet again, as for me this is annoying, and if I am asked to do anything important with my camera, I don't want others complaining of this.
There are 2 examples of dropped frames here by another 5D user
http://www.landoimages.com/JefferyLando/drop_framesh264.mov
http://www.landoimages.com/JefferyLando/drop_frames2h264.mov
And here are a couple of examples of a hot pixel
http://www.youtube.com/watch?v=0S2bl-CgMMM
http://www.youtube.com/watch?v=6kv-w1E6WX4
My suggestion to anyone going to buy an HD SLR, is if you take your laptop with you and a spare battery for it fully charged, then you can give it a test before leaving the shop, and avoid the inconvenience of repeated trips back. A spare battery shouldn't seen as being an added expense, as I assume anyone buying one of these is a seriously into photography, and will have more than one battery; so just buy it in advance. If you buy your camera on line then you will be asking for trouble. These cameras are as cheap in stores as they are on line, so don't buy on line or you'll be paying a fortune in postage costs if it has these problems
