Canon EOS 5D Mark II review
Performance Page 2
The standard focusing system is largely unchanged from the original 5D, though its square markings are a little darker and more defined. Canon's reason for not including the all cross sensor system seen in the EOS 40D is that it found the AI Servo tracking mode to be more effective on the original 5D, despite having only one cross-type point. As with the 40D, its configuration sees nine points arranged in a diamond pattern, though the increased size of the sensor means that their spread is over less of the total area, and more confined in the centre.
This presents a problem with the camera finding subjects off-centre, meaning that focusing using the more sensitive centre-point and recomposing is sometimes necessary. Worse still, trying to pan a subject horizontally when holding the camera in a portrait orientation means that the camera only has three points to work with (in addition to the six invisible points inside the spot metering circle). As the points are so close in the centre of the frame, once your subject steps outside of these the camera is no longer sensitive to picking up any of its movements. It's less of a problem along the horizontal as the points are spread out over a greater area. Overall, though, the camera works well to track subjects providing you keep them in the centre of the frame, and focusing in general is also very good. What's particularly impressive is that the outer points are still quite responsive, in comparison to the central point.
I knew the 920,000dot LCD screen would be a huge improvement (and boy was it time for one) but I was still surprised at just how well it could be viewed in bright conditions. With no less than five separate coatings, even harsh sunlight didn't prevent a sufficient level of contrast displayed for reviewing images. Comparing it with that of the Nikon D3X (which we're also reviewing at the moment), the 5D Mark II's screen seemed to have the edge in terms of contrast and its refresh rate was noticeably quicker.
On a different note, I did notice images were written relatively slowly to non-UDMA cards, when capturing Raw and JPEG images simultaneously. It's also a little disappointing that the optional BG-E6 battery grip offers no increase in the camera's burst rate, in the way that this is possible with Nikon's MB-D10. I am, however, happy to report that the Periphal Illuminantion Correction feature works well and lifted vignetting effectively from images shot wide open
The 24-105mm f/4 L IS USM lens that ships as a kit option with the 5D Mark II proved itself to being a capable partner, with very good sharpness, excellent defocusing chracteristics and smooth, round bokeh. It's no stranger to chromatic aberrations though, particularly at the edges and corners, where softness also appears - even when stopped down. There's also noticeable barrelling at the wide end.
Finally, despite shooting a number of long exposures, I couldn't find any instances of the black dot phenomenon which early users have spotted. My guess is that the issue is confined to a number of samples, rather than being an inherent flaw to the camera. In any case, Canon is currently working on a firmware update that should resolve the issue for any affected cameras.