"Can the 5D output higher than 1080p? If not, then how is it rated at
5k? I read a post by Jim on reduser.net ("Resolution 101") in which he
compares the resolution of the 5D with various RED models. It seems the
5D delivers less resolution, after the conversion to 1080p."
Anindya,
As you may have read in post you mentioned the 5DmkII has a CMOS sensor that tops out at 21.1 megapixels (5,616 x 3,744 pixels) which is larger than the RED ONE's 12 megapixel (4520 x 2540 active, 4096 x 2304 max recording.) I guess for engineering reasons and to keep the cost of the rig down, Canon decided to down sample the images from the sensor for HD video by only using every third line making it 4:2:0 chroma sampling instead of 4:2:2 or 4:4:4 had they used more lines.
The RED ONE also hamstrings its sensor as well just not as significantly as the 5D. But the 5Dmk II is no doubt a 5k camera. Even if you can capture directly from the HDMI out to a laptop or such, I'm not sure how much of an extra bump in picture quality you'd get. So far I have yet to see a rig or adapter that would allow you to capture directly.
One thing is for sure, despite it being 'hamstrung', imagery shot with the 5D holds up to stuff shot with the RED side by side when blown up to theatrical sized projection. Now, the RED color corrects more fully from what I've seen but I can't give it a full thumbs up against the 5D in that respect because Ive only seen one example.
For more on the discussion of the MkII, 5k and a side by side comparison of the RED, 5D and others check out my past posts:
5k Anyone? and Advanced Info.
And that wasn't much of a 'defense' of the RED. You must be British-based English speaker based on your spelling the word with a 'C'. I say old man th' ball is in your court sir!