Canon's EOS 5D Mark III has a lot to live up to. For a start, the original Canon EOS 5D was
the first DSLR to really bring full-frame digital photography within the reach of enthusiast photographers. Then came its replacement, the Canon EOS 5D Mark II, which kick-started the current trend for shooting video on a DSLR.
So naturally, as the 5D Mk II clocked up its third birthday in September 2011, the rumour mill slipped into overdrive with lots of speculation about the likely specification of the 5D Mk III.
Even its name was a subject of debate, with Canon EOS 5DX and EOS 6D being other suggested alternatives.
By the time Canon actually announced the EOS 5D Mark III on March 2 2012, its specification seemed almost a bit of a letdown, especially priced at £2,999 in the UK and $3,499 in the US for the body only.
But while it might not have the headline-grabbing 36MP pixel count of the Nikon D800, Canon's latest full-frame camera has lots to offer enthusiast photographers.
Specification
With 22.3 million effective pixels, the Canon EOS 5D Mk III's sensor only has 1.2MP more than the 21.1MP Canon EOS 5D Mk II that it replaces, but it has 4.2MP more than the 18.1MP Canon EOS-1DX at the top of Canon's DSLR lineup.
Whereas the Canon 1DX has two Digic 5+ processors, the 5D Mk II has one, which in combination with its eight-channel readout means that it has a top continuous shooting speed of 6fps.
This is half the rate of Canon's top-end camera, and it may disappoint those hoping for something in the region of 8fps or more. It's a big jump from the 3.9fps of the Canon 5D Mk II, though, and the burst depth is an impressive 18 raw images or 16,270 JPEGs (when a UDMA 7 card is used).
Sensitivity may be set in the range of ISO 100-25600 in 1/3-stop or whole stop increments, and it can be expanded to include L: ISO 50, H1: ISO 51200, H2 ISO 102400
Autofocus
The Canon EOS 5D Mark III has the same 61-point wide-area autofocus system as the flagship Canon EOS-1DX. This is a big improvement on the Canon EOS 5D Mark II, which has nine user selectable AF points and six assist points, giving a total of 15.
Of these 61 points, 41 are cross-type and five are dual cross-type points, which is good news for accuracy. The customisable AF presets introduced in the Canon EOS-1D X are also available, which Canon claims helps when shooting more challenging subjects.
It doesn't offer the f/8 sensitivity of Nikon's latest system though - it only extends to f/5.6, which restricts the use of teleconverters.
Metering
Predictably, Canon has upgraded the metering system to its iFCL metering. Existing Canon EOS 5D Mark II users may find it takes a little getting used to as it reacts in a similar way to centre-weighted metering and puts greater emphasis on the subject under the active AF point.
In some situations this is a blessing, but with exceptionally dark or light main subjects the results may not be the same as the Canon EOS 5D Mk II would produce in its evaluative metering mode.
Video
Its video capability was one of the big successes of the Canon EOS 5D Mark II, and Canon hasn't changed much of its specification for the Mark III version, but there are some significant improvements.
Firstly there's the introduction of a live view/movie switch on the rear, like on the Canon EOS 7D, to speed up movie activation.
There's also a headphone socket for monitoring the stereo audio, which can be adjusted in the same way as that on the Canon EOS-1DX.
HDR
Until now Canon hasn't had a DSLR with in-camera HDR recording, but the Canon EOS 5D Mk III is capable of recording and merging three shots to produce a high dynamic range image.
This is extremely useful, since it records all three shots as well as the processed HDR image, and if you shoot raw and JPEG images simultaneously, you'll find you have a total of seven images, including three raw files that you can process yourself if you wish.
Another difference between the Mark 2 and 3 versions of the Canon EOS 5D is that the newer camera has two card ports, one for compact flash and the other for SD format cards. There's no XQD card port.
source: http://www.techradar.com