I got sucked in…
Normally I have the good sense to steer clear of photography forums. Too often these are the hangouts of folks with firmly held opinions unencumbered by facts.
I am more of a facts type of guy.
The 5D Mark II seems to have brought out all the usual suspects. Among the poorly reasoned arguments and tortured logic presented as facts is the persistent complaint that Canon was wrong to put a 21 MP sensor in the 5D Mark II. Except for landscape shooters and maybe some commercial types, no one needs that many pixels. In an homage to all that Nikon can serve up at the moment, the consensus seemed to be that 12 MP is, and will continue be, to all that most folks need.
I currently shoot with a 21 MP 1Ds Mark III and also shot the original 12 MP 5D for most of two years. Assuming that Canon has retained the image quality of these two cameras (and early samples seem real promising) it is my experience that more pixels are better than fewer.
I dislike hate vertical 3:2 aspect ratio images. It is, more often than not, just too damn tall. I much prefer the a traditional 4:5 vertical crop.
21 MP gives you the luxury of tossing pixels out and doing so without remorse. The standard 5624 x 3736 pixel 1Ds3 capture is reduced to 4887 x 3736 when cropped to 4:5. The crop results in a 50 megabyte tiff file. The math is far less favorable to a 12 MP camera. The original 5D starts at 4372 x 2906 pixels and drops to 3310 x 2650 when cropped to 4:5. The cropped tiff weighs in at 25 MB.
Similar math applies to horizontals. Here 3:2 is tolerable but something more like 2:1 or it’s close HD cousin 16:9 look even better.
For the folks who just can’t seem to afford all the storage that larger RAWs and JPEGs produce. With one terabyte bare drives costing $160 or less, storage is the cheapest thing in my photographic ecosystem.
And if you are still unconvinced. Canon feels your pain. In addition to two reduced size JPEG sizes, the 5D Mark II has two pint sized RAW file sizes. sRAW1 is a 10 MP capture and, in an homage to the omnipresent web banner, sRAW2 weighs in at 5.2 MP.