Camera Test: Canon EOS 40D

	Click photo for more images of the Canon EOS 40D.

Canon's EOS 30D was the DSLR middleweight contender to beat for most of 2007, thanks to its tough body, great image quality, fast autofocus, and semi-pro controls. So it's no surprise that the new 10.1MP EOS 40D ($1,300, street, body only; $1,500, street, with EF 28-135mm f/3.5-5.6 IS USM lens) holds fast to the 30D's overall body design and exposure controls. In fact, from the front it's hard to tell them apart.

Inside, though, Canon's engineers found ways to raise the 40D's image quality, boost its burst rate, speed up the AF system, and improve the viewfinder. Around back, they even squeezed in a 3-inch LCD with live preview mode.

Is there enough punch in the 40D's new features, and price to keep it from being knocked out by new contenders from Nikon, Olympus, and Sony? We'll know for sure in the next few months as we run all of those cameras through the Pop Photo Lab and our field tests.

But after testing the 40D, one thing is certain: it's better than the 30D and a lot of DSLR for the money.

We were surprised that Canon upped the 40D's CMOS sensor only to 10.1MP (the same as its Digital Rebel XTi). By comparison, Nikon's older D200 ($1,500, body only, street) has a 10.2MP CCD, and the new Sony Alpha 700 ($1,400, body only, street) packs a 12.2MP CMOS.

But as we keep saying, megapixels are just one factor to consider when buying a camera. The 40D is a case in point: Improvements in sensor design, color accuracy, noise reduction at high ISOs, image processing, dynamic range, and AF accuracy have had a greater impact on image quality and performance than merely boosting the megapixels would have.

At the sensor level, Canon modified the microlens arrangement to increase the 40D's light sensitivity and reduce light falloff towards the corners. Next came the higher-powered DIGIC III image processor and a 14-bit per color A/D (analog-to-digital) converter.

As a result, the 40D's resolution averages 2100 lines from ISO 100 to 1600 -- nearly identical to the Digital Rebel XTi, up quite a bit from the 30D's 1720 lines, and only 100 lines below the pro-level 10.1MP Canon EOS-1D Mark III ($3,900, body only, street). Color accuracy also is Excellent at both ISO 100 (average Delta E of 7.7) and ISO 1600.

The biggest gains come in the form of lower noise at all ISOs, ranging from Extremely Low (ISO 100 to 200), to Low at ISO 800, Moderately Low at ISO 1600, and only up to Moderate at ISO 3200! These results were achieved without turning on the 40D's High-ISO Noise Reduction, and are in the same class as that low-noise counter-puncher, the Nikon D200.

In all, the 40D earns an Excellent image quality rating from ISO 100 to 1600, and an Extremely High rating at its extended ISO of 3200.

In high-contrast field tests, the 40D captured plenty of detail in shadow and highlight areas, and in portrait tests, produced very smooth gradations and accurate skin tones. Improved image quality controls borrowed from the 1D Mark III include Highlight Tone Priority and High-ISO Noise Reduction.

The Gloves Are Off

Excellent image quality in the lab translates to excellent image quality in the field if a camera's autofocus, exposure and metering systems, and viewfinder are all top notch. And here, the 40D is hard to beat. Its AF system is among the fastest and most sensitive we've tested, capable of extremely high speeds in bright to moderate light, and decent performance down to EV-2.

Through the viewfinder you see an AF-zone array similar to the Rebel XTi's, but the 40D's nine zones have the more sophisticated cross-type sensors (active with all f/5.6 or larger-aperture lenses), plus a highly sensitive center zone that's active with lenses opening to f/2.8 or more. This improved AF speed and tracking accuracy will come in handy when shooting action and fast-moving subjects, especially in the 6.5-frame-per-second burst mode.