Editors' note: The competitive landscape for this camera has changed since our review, and we've updated the text and ratings to reflect that and the model's lower price. The design rating goes from a 9 to an 8--while still a nicely designed model, it's not particularly outstanding anymore--and features drops from an 8 to a 7 for its efficient-but-now-relatively-mundane set of capabilities. Text changes include comparisons to newer models.
Representing a more significant leap over the EOS 30D than the 30D was beyond the 20D, the Canon EOS 40D features a redesigned body and menu system, introduces some long-requested features, integrates some of the new technology from the EOS 1D Mark III and delivers a nice bump in resolution and performance. All of that, plus a solid overall increase in speed over its predecessor, make it a no-brainer upgrade from previous models, a substantially better option than its down-the-line sibling, the EOS Rebel XSi and a nice complement for the EOS-1D Mark III.
Canon offers two configurations of the 40D: body only, and a kit with the veteran f/3.5-to-f/5.6, 28mm-to-135mm IS USM lens. Taking into account the camera's 1.6x focal-length multiplier yields an angle of view equivalent to that of a 44.8mm-to-216mm lens on a 35mm camera. That's a bit narrow, though; personally, I think the admittedly pricey EF 24mm-to-70mm f/2.8L USM covers a more useful general-purpose range of 38.4mm to 112mm. Alternatively, you may want to wait until later this year when the inexpensive EF-S 18mm-to-55mm f/3.5-to-f/5.6 IS is slated to become available.
Despite the growth of the LCD from 2.5 to 3 inches, the body size and weight of the 40D is the same as that of the 30D: 4.2x5.7x2.9 inches and roughly 1.8 pounds. As with its predecessor, the body feels very solid and well made, one of the important advantages it has over the flimsier-feeling Rebel series. Canon added dust- and weatherproofing on the CF slot, the buttons, and all connection points, and it implemented the same integrated sensor-cleaning system that's in the Mark III series. The latter vibrates the sensor to dislodge dust during start-up and shut-down (pressing the shutter cancels cleaning during start-up), and if that doesn't work, a Dust Delete Data option enables the camera to analyze and remember where it senses dust and algorithmically remove it from photos.
The larger LCD did make it necessary to rejigger some of the controls. The Review, Delete, Jump, Info, and new Picture Styles buttons now sit below the LCD rather than to the side, and the buttons are substantially smaller than before. They also sit flatter and more flush with the body, making them harder to feel and press. Along the same lines, the Metering/WB, AF/Drive, ISO/Flash compensation, and LCD backlight buttons, which seem to rise slightly higher than previously, feel identical and impossible to differentiate from one another.
On the upside, the 40D has a bigger, more tactile mode dial, with three slots for User settings (the 30D had none). Although I find these invaluable, there's one behavior that really annoys me: if the camera goes to sleep, it resets any setting overrides you've made while in one of the user modes.
Canon also redesigned the grip, adding a curved indentation just below the ledge with the shutter button, where your middle finger falls. It's a subtle but nice ergonomic enhancement that makes the grip feel just a little more solid. Canon also redesigned the menu system, which is now far easier to read and navigate. (Click through a slide show discussion of the body design and menus.)
A few new features have also popped up with the 40D. Most notably, it offers a Live View mode, with a better, more flexible implementation than that of the 1D Mark III--or most others, for that matter. Unlike its big brother, you can autofocus in Live View; when you press the AF-ON button, it flips the mirror down, focuses, then flips the mirror back up so the focus-corrected view appears on the screen. On the downside, it focuses only using the center AF area. And regardless of focus mechanism, it uses only evaluative metering.
As with a point-and-shoot camera, you can pull up a magnified view to help with manual focusing. In addition, three so-called "silent shooting" options allow you to control the shutter curtain reset to delay the noise and minimize vibration. Though hardly "silent," the 40D does have one of the quieter Live View modes I've encountered. You can also set the metering timer, how long the camera holds and displays the metering information after you release the shutter button, anywhere from 4 seconds to 30 minutes. I'd love this feature to be available for general shooting rather than limit it to Live View. All that said, Live View shooting continues to be a bit of a niche application for dSLRs; generally, it's suitable only if your subject matter allows for a tripod and optimally a connected PC for remote control. Keep in mind that the sensor can get warm in this mode, and as Canon warns, increased heat will result in increased image noise.
For more meat-and-potatoes changes, the 40D now supports Auto ISO in all modes beyond full Auto, which comes in handy every now and then. The new viewfinder system supports interchangeable focusing screens and, for all you four-eyed photogs, offers a relatively high 22mm eyepoint and slightly greater magnification than that of the 30D, 0.95 vs. 0.90. Canon also added an sRaw format, which shoots small, 2.5-megapixel raw images. I don't see the utility of this feature, but it's easy enough to ignore. Not so easy to ignore is the increased spot size for the spot meter, up to 3.8 percent of the viewfinder from the 30D's 3.5 percent. (Here's why that's bad.)