bayer + scale?

A

arrestthisman

Well-known member
Ok I've looked EVERYWHERE, and I can't find any hard information on how the 5d, or 7d, or gh1 achieves its 1080p video.

If it's out there on the thread I hope it becomes a sticky.

Quite simply: Does the 5d downscale the whole sensor, skip lines, etc... and does it use striping or bayer? Along with that, with whatever tricks they use to get the 1080p, what is the real resolution?

Thanks for anyone who can shed even a little light on this. I'm seriously considering the camera, and even thought the footage is 10x more important than specs, I won't buy a product unless I know the specs as well.

So once again, thanks. Take care,
 
The answer is that nobody knows for sure. Neither Canon nor Panasonic nor anyone representing those companies has made any statements about the matter.

However, for the 5D and presumably the 7D, the type of aliasing seen in the footage would suggest line-skipping as the most likely explanation. But that's still conjecture and should not be treated, nor repeated, as fact.
 
This topic just came up on cinema5d, and there is a video where Tim Smith from Canon talks about how the 5DII uses binning in pixels of 6 to get their 1920 image. Someone over there managed to post a direct link to it, their site is running slow so I'll post the page here:

http://digitalcinemasociety.org/content.php?page=Lighting Workshop

Go to the video titled Clip Smith1, about half way through he talks about how the aliasing issues and there's a brief part where he talks about the binned pixels and emphatically denies using line skipping

The only other piece on the internet I know about is about the video for the Pentax K-7 by falconeye. In one article he talks about a potential 6x6 sampling matrix that the K-7 may be using for its live view/video (it's probably not exactly right but comes close):

http://falklumo.blogspot.com/2009/06/k-7-as-movie-camera-part-i-technical.html

Don't know how similar it is to Canon or Panasonic's way of generating video, but the K-7 is resolving a similar level of detail at 1024p as the T1i's video at 1080p (I have a K-7 and have been borrowing my dad's T1i this weekend, the levels of detail are very close except at higher ISOs, where the K-7 keeps more detail indoors at the expense of higher noise)

There is one site on the web that attempts to measure resolution from camcorders and has recently started to review DSLRs, it's at:

http://www.digitalcamerainfo.com/d/DSLR-Video.htm

I was surprised where they found the T1i had the sharpest video off a DSLR they had tested, which came in at a horizontal resolution of 650 lw/ph and a vertical of 775 lw/ph. The GH1 came in at 750 horizontal by 650 vertical. The 5DII had a resolution of 700 horizontal by 650 vertical. The d5000 came in at 575 horizontal by 625 vertical and the EP-1 was 600 horiz by 650 vert. All were measured at their highest resolutions.

To me all those numbers are disappointingly low, but not unbelievable. You can downsample a 5DII or T1i video (or K-7) to numbers down to 1000 pixels across or even a bit lower, then resample them back up and you won't lose detail. None come close to resolving 1280, much less 1920, lines of detail (but neither do consumer camcorders for that matter)
 
Well certainly the Tim Smith video is a must-watch for anyone interested in the topic and one of the most candid explanations (albeit very brief) of how video works on a Canon DSLR. After viewing both of the Smith videos he touched on a lot of topics that often come up with the camera, with the notable exception of the feasibility of 24 fps on the 5DII
 
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