“The Canon EOS 1D Mark IV is the fifth generation of Canon's speed-orientated range of professional DSLRs. It retains the two-grip form factor of the original, 4MP EOS-1D launched in September 2001 (itself building on the integrated grip of the film-era EOS-1N RS, also the first to offer 10fps shooting, albeit without AF between shots). And it's this consistency of design, which extends to the AF pattern and much of the control layout, that helps to explain the name – the Mark IV really is the current point in an evolutionary process, rather than a wholly separate model.
However, more than previous 1D series cameras, the 1D Mark IV has a lot to prove. Whereas, in the past, Canon's flagship models have been a fairly safe bet, autofocus problems with the 1D Mark III have cast a shadow over the range. Those problems, which appear to have come from a combination of manufacturing error, increased complexity of AF customization and the AF sensor occasionally being overwhelmed in bright conditions, have become notorious.
These issues, combined with the coincident arrival of the Nikon D3 that offered, for the first time, an equal level of AF sophistication, brought into question Canon's long-held position as AF front-runner. Since then, however, a combination of engineering revisions and user education have meant that many shooters have been able to use the camera without any problems – Canon admits there have been issues, but the woes that were so widely reported early in the camera's life span are unlikely still to be affecting nearly as many users as its internet reputation might suggest.
Canon is clearly hoping to assuage any doubts still lingering after the ‘1D III Affair' by introducing a new AF system. Although the 45 AF points are arranged in a layout that dates back to 1998's EOS 3, the 1D Mark IV uses a totally new AF sensor with 39 cross-type points that are sensitive both in the vertical and horizontal axis. The AF point selection method has also been revised, both for manual selection and for automated selection with subject tracking via the new AI-Servo II system.
The 1D Mark IV retains its predecessors' 1.3x crop, APS-H sensor size, but this time increases its pixel count to a whopping 16MP. This may not seem like many in the era of 25MP full-frame DSLRs and 14MP compacts, but it's a lot when you consider the Mark IV still has the ability to shoot at 10 frames per second. If you consider that this is almost the same resolution as offered by the last generation of Canon's studio-targeted camera, the 1Ds Mark II, but with the ability to shoot twice as fast, then you start to appreciate what this camera is promising to do.”
So, walk, don't run, right over to the DPReview review.
(Photo credit: snap from the DPReview review)