Canon EOS 5D Mark III review

The Auto ISO mode is more configurable than in previous EOS cameras, with the ability to define the minimum and maximum speeds, and also define a minimum shutter speed threshold. It’s not as flexible as the D800’s, though, as the fastest setting of 1/250s isn’t enough to freeze fast motion. There’s an Auto option for this minimum shutter speed control, which adapts to take into account how camera shake is more likely at longer focal lengths. However, there’s no option to shift the Auto threshold to faster or slower sets of values, as on the D800.

The 5D Mark II was the first SLR to record 1080p video. Today it’s a standard feature across the board, but the Mark III comes with some significant upgrades. AVC compression is at bit rates up to 30Mbit/s, but there’s an option to use all I-Frames, whereby each frame is described from scratch rather than using sub-frames that only describe what’s changed since the previous frame. This generates files up to 90Mbit/s but reduces compression artefacts in fast-moving scenes. Thankfully, clips can span multiple 4GB files up to a maximum of 30 minutes. There’s a choice of 24fps, 25fps or 30fps frame rates, but considering the much faster processor, it’s disappointing that there’s no 1080p capture at 50fps or faster for slow-motion effects.

Comparing stills from each camera’s 1080p video output (shot at f/5.6, ISO 200, 1/50s), they all look pixel-sharp but the Canon can’t match the Nikon D800 or Panasonic GH1 in its ability to capture subtle textures in the soft toy – click to enlarge

The Mark II had a choice of automatic or manual exposure control for videos, but the Mark III adds shutter- and aperture-priority control. The ability to fix the shutter speed at 1/50s for consistent motion blur and let the camera expose automatically using the ISO speed is a major breakthrough, and something that the Nikon D800 lacks. It’s also possible to adjust exposure settings using touch-sensitive controls to avoid mechanical clicks spoiling the soundtrack. There’s no resolution to EOS cameras’ terrible autofocus for video, though. Pressing the AF-ON button while recording overrides manual exposure settings and causes the focus motor to dart violently back and forth.

Details in video clips weren’t as sharp as we’d hoped for, either. The D800 coped better with subtle details such as skin textures and foliage – the 5D Mark III’s output resembled lower resolution footage that had been digitally sharpened. However, this may be the result of Canon’s efforts to rid videos of moiré interference, whereby dense patterns result in swirling lines of interference. This has been a bugbear of ours for some time, and it’s a relief to finally find an SLR that doesn’t exhibit it. Audiences probably won’t be too upset by a slight lack of detail, but psychedelic interference can be really distracting. However, neither the 5D Mark III nor the D800 could match our aging Panasonic GH1 for detail in videos, at that doesn’t suffer from moiré either.