As a working Professional Photographer I have used many different cameras over the years, including almost all of Canon and Nikon's DSLR offerings.
Finding the right camera is tricky, with many factors coming into play. No camera is perfect for every job, but one camera comes close: the Canon 1D Mark III.
First off, don't sweat the 10 megapixel resolution. Image quality is exceptional, and the 1D Mark III is sharper per-pixel than any other camera out there. There is no difference in the total amount of deatail captured between the 1D Mark III and Nikons D3 or D300 cameras. Noise is also lower than on any camera that has come before. This is the first camera where ISO 100-800 is simply a choice, based of the needs of the photo. There is zero sacrifice in image quality at ISO 800. Of course the 1D Mark III goes from ISO 50 to 6400, and every step of the way it outperforms all cameras that came before it. Nikon's D3 and D300 also have very low noise, but details and contrast start to suffer on the Nikons for ISO 1600 and up. Not so with the 1D Mark III, everything stays sharp and crisp.
Speed is what the 1D Mark III was built for, and in that regard it is obscenely fast, in every respect. That speed is enhanced by an amazing new battery that is good for over 2000 pictures per charge (sometimes over 3000 pics).
The 1.3X crop factor is a boon most of the time, except that there is only one super-wide option that really works (Sigma's 12-24mm). However with Canons 16-35mm L lens you get 20mm equivelent field of view, which often is good enough. However the advantages of a 1.3X crop are similar to a 1.5/1.6X crop in that you use the sweet-spot of a lens, which keeps things sharp around the edges... but with a 1.3X crop you use more of the lens, and this matters because most lenses are out-resolved by 8 megapixel sensors, which results in many 1.5/1.6X cameras producing slightly blurred images regardless of the resoltion. The 1D Mark III really takes maximum advantage of a lens, which is a decidedly good thing.
One really outstanding benefit of the 1D Mark III is the new Highlight Tone Priority mode, which expands dynamic range by one full f/stop in the highlights. This feature is now included on the Canon 40D and the 1Ds Mark III as well, but it works best on the 1D Mark III because of the incredibly low noise characteristics of this camera. There is zero penalty in image quality for using Highlight Tone Priority, something wedding photographers might consider when comparing this camera to other models.
There is so much more to say about this amazing camera, but not enough time or space to say it. The price is steep, but the performance of the 1D Mark III truly justifies the cost. Anyone who shoots sports, action, fashion, birds, wildlife or even a baby making faces will absolutely appreciate the 10 frame-per-second, 110 JPEG Buffer (or 30 RAW)... and that even at full-speed the 1D Mark III is operating at full capability (Unlike the Nikon D3 which
Orignal From: Canon EOS 1D Mark III 10.0 Megapixel