It does not use max aperture all the time.
It seems to use an odd program which tries to keep the shutter speed between 30th and 125th by varying the ISO and the aperture. if you use it in full sunlight you'll probably get F16 @125th @ 200ISO, indoors it might be 30th F2 and ISO3200. I'm still getting to grips with this, but you can adjust exposure using the exp comp dial, this seems to change ISO rather than aperture or shutter speed.
The auto metering also seems to change apertures in big jumps ie F5.6 to F16 or F5.6 to F2. I intend to find out more over the coming week...
I don't know if there is a technical reason for this or a marketing reason, actually I don't care, but it's a dumb ass move to make any camera that doesn't allow you control of the shutter, f stop and iso.
The indie market has been waiting forever for a digital video camera that offered a frame size large and detailed enough to select focus and artistically make a decision on where you want the viewers attention to be focused and at first I thought the 5dII would be it, but unless there is something in the submenus that let's us overide these auto functions, mine is going back to the dealer.
As it stands now, the only way I know to even gain some control over the MarkII is to use Nikon manual lenses and carry a box of nd filters for each lens, which is really stupid when you think about it, because all this has done is make a 5dII user go onto KEH and buy Nikon lenses rather than new Canon lenses.
At least the little Nikon N90 using manual lenses, let's you select F stop with a fixed shutter speed, even though the rolling shutter and jello cam is a big pain in the ass.
For too long, in both stills and motion, camera makers have held back protecting one cameras market from another camera and at this stage of the economy and at this point in technology they need to stop it.
If Canon wants to offer a mark II/video version that allows us to make the cameras decisions and charge another $1,000 or more then fine, do that, but don't offer video then hold back on usability, because we're all tired of this incremental marketing approach.
I don't know where RED is on the scarlet and I do find it somewhat refreshing that the owner of the company actually answers questions and gives honest responses and I hope their next round of cameras does everything they advertise (though that seems to change weekly), especially since the new cameras seem to be on a modular path, so as improvements come to market you don't have to throw away the whole camera.
I hope RED blows them all out of the water.