The original Canon EOS 5D, released just over four years ago, offers a full-frame sensor - a sensor that's the same size as a piece of 35mm film. Most digital single-lens reflex cameras (SLRs) use a small sensor that "sees" only the middle section of a lens, effectively giving your lens a crop that's equivalent to a lens with a longer focal length.

When you put a lens on a full-frame camera such as the Canon EOS 5D, it works just as it would if you put it on a 35mm film camera - there is no focal length multiplier like there is when you use a camera with a cropped sensor. The larger sensor also allows you to achieve a shallower depth of field.

Talk to any fan of the Canon EOS 5D (which is mostly anyone who ever used one) and they'll extol the camera's ability to shoot images that have a film-like quality, a little something extra. It's a testament to the quality of the original EOS 5D that it stayed on the market for almost three years before Canon released an update, the new Canon EOS 5D Mark II.

With the EOS 5D Mark II, Canon has made some significant interface changes, upped the pixel count from 12 to 21 megapixels, improved the high ISO performance and expanded the ISO range, and added the ability to shoot high definition video. The result is a great camera made better.

Canon EOS 5D Mark II: interface changes

The EOS 5D Mark II follows the same design as its predecessors, going all the way back to the original EOS D30. Sporting a very simple control layout, the Canon EOS 5D Mark II is a camera that you can easily operate one-handed if you have to, and adjusting all essential image parameters is very simple.

However, with the Canon EOS 5D Mark II, Canon has made some small but significant changes to the design of the original EOS 5D. First, the back of the camera now sports a 3in LCD of exceptional quality. The LCD is a 920,000-dot VGA display, similar to the displays that Nikon has been using on its recent SLRs, and it's a great improvement over previous Canon LCDs.

The EOS 5D had a 2.5-inch LCD; the Canon EOS 5D Mark II's larger screen necessitated the rearrangement of some of the buttons on the back of the camera, and it might take current EOS 5D owners some time to get used to the new placement of the Playback and Delete buttons.

Users of previous Canon bodies will also need to adjust to Canon's rearrangement of certain functions on the top-mounted buttons. Some functions now sit on different buttons, and are controlled using different control wheels. While this can take some time to get used to, with the Canon EOS 5D Mark II the result is an interface that makes it easier to change essential parameters, such as ISO, without taking your eye from the viewfinder.

The most important interface changes are the addition of custom modes and a Custom menu. The Canon EOS 5D Mark II's Mode dial (which you use to select a shooting mode) now includes three custom modes; you can configure the camera any way you want, and then store that configuration in one of the custom modes.

For example, we set up a special mode for shooting HDR. When we switch to that mode, the Canon EOS 5D Mark II automatically goes to aperture priority and enables auto-bracketing and drive mode. Custom modes also make it easier to get to functions that are normally difficult to access, such as mirror lock-up.

A new Custom menu lets you create a menu with only items that you want. If you normally find yourself regularly switching between a few menus, this feature will save you a lot of time.