Updated: read our full review of the Canon EOS 5D Mk II.

It's been a long time coming, but finally, a replacement to the popular Canon EOS 5D has arrived, in the form of the 5D Mark II.

And not a moment too soon – Canon might have had the enthusiasts' full-frame DSLR market to themselves for almost three years, but in recent weeks, new cameras from Nikon (D700) and Sony (Alpha 900) have challenged Canon's monopoly, and making the original EOS 5D look very old fashioned by comparison.

'Old fashioned' is a criticism that is very unlikely to be levelled at the EOS 5D Mark II however, and whilst some aspects of the feature set remain largely unchanged, (along with its list price) this is not the minor upgrade to the original 5D that the 'Mark II' suffix might suggest.

Improved sensor

The first major improvement is in the sensor. Twelve million pixels was a lot three years ago, but photographers are harder to impress in 2008 than they were in 2005, and the EOS 5D Mark II's resolution has been increased to 21 million pixels. That's the same resolution (albeit apparently not from the same sensor) as Canon's full-frame flagship, the EOS 1Ds Mark III.

More impressive than its pixel count, however, is the fact that as well as still images (which can be captured at 4fps for more than 70 JPEG frames) the EOS 5D Mark II can also capture video. Proper video. High Definition video, in fact, and unlike the Nikon D90, which recently took the prize for the first HD-equipped DSLR, the 5D Mark II can shoot 1290 x 1080p at 30fps.

In HD mode, footage is limited to bursts of around 12 minutes, but if quality is not the ultimate priority, the camera can shoot for twice the length of time in VGA (640 x 480) video mode.

We had the opportunity to give the EOS 5D Mark II an extensive work-out at the UK launch, and video from the new camera looks great – sharp, detailed, with no discernable lag at all.

Bright LCD screen

Arguably less exciting, but equally noteworthy improvements include a much better 3-inch, 920,000 dot LCD screen, which is now equal in specification to the best that we've seen from Nikon and Sony, and many of the same handling refinements that were introduced in the EOS 50D.

These include a new quick control screen, which allows the user to directly access most key functions from a status screen on the main LCD, and a newly reconfigured Direct Print button.

Many Canon users have been complaining for years about the baffling prominence awarded to the little-used Direct Print button on the rear of most Canon DSLRs, and now, with the 50D and 5D, this button can also be used to activate Live View. Hooray for common sense.

In what may prove to be a less sensible development, Canon has given the EOS 5D Mark II the widest ISO span of any current DSLR, from ISO 50-25,600.

Clear View feature

If image quality at the highest ISO settings can match what Nikon has managed to achieve from the lower resolution sensors of the D3 and D700, then Canon has managed quite a feat, but our initial findings (peering at a magnified image on the camera's LCD screen) suggest that Nikon users shouldn't be considering a system change quite yet.

The new 'Clear View' screen makes a huge difference to picture quality in Live View, and compared to the screen in the original EOS 5D, the new camera's LCD offers a level of contrast, clarity and detail that is simply breathtaking. In fact, we're tempted to say that pending a direct comparison, the screen on the new EOS 50D and 5D Mark II may even be the best currently on the market.

In use, the EOS 5D Mark II feels like what it is – the hybrid of a proven body, with newer, more advanced models. The finish is magnesium alloy, like the original EOS 5D, but weather sealing is much improved, and the surface of the camera is textured, in the same way as the EOS 1D and 1Ds Mark II.

Improved controls

The styling is more up to date too, and Canon has taken the opportunity to standardise the control layout of the 5D Mark II, to bring all of the current EOS range into a kind of ergonomic homogeny designed, presumably, to bring comfort to its more promiscuous customers.

It will take a full test to translate a promising spec sheet into actual performance, but for now, the EOS 5D Mark II certainly counts as one of the most exciting DSLRs that we've ever seen. Full review coming soon.