Canon EOS -40D

  
Manual Control Options
The EOS 40D offers full manual control over exposure, fine tuning of White Balance, ISO expansion, and 3 sets of user-defined settings and 24 custom functions.

Focus
Autofocus (8.5)
Consistent with previous models in the line, the EOS 40D has nine autofocus points arranged in a horizontal diamond-shaped pattern around the center of the frame. All nine points are cross-type, however, unlike the EOS 30D that had just a lone cross sensor in the center. The central focus point on the 40D has been also reworked; the diagonally-oriented, high-precision sensor is now sensitive to vertical and horizontal lines with f/2.8 lenses and faster. High-precision autofocus sensors in previous EOS cameras were only sensitive to vertical lines with f/2.8 lenses.

Three focusing modes are offered: One-shot (focuses for single shot), AI Servo (automatically switches between focus points to track moving subjects), and AI Focus (moves between one-shot and AI Servo).

The system sounds impressive on paper, but in use, it didn’t meet Canon’s marketing bravado. We found the 40D struggled to find focus in low contrast scenes, and would often hunt when the Nikon D200 would lock in. The EOS 40D fared better than the 30D in low light scenes, but needed a good deal of contrast to be effective. In low light, low contrast scenes, there wasn’t much discernable difference between the 30D and 40D. Tracking performance was decent using its AI Servo setting, though twice we found it jumped off subjects we were following without reason. In general, the 40D offers upgraded autofocus from the 30D, though the improvement is not as significant as we had hoped.

Manual Focus (9.25)
The Standard Precision Matte (Ef-A) focusing screen that ships with the camera is surprisingly contrasty and makes it easy to judge focus in the viewfinder, even using the kit lens. Unlike the 30D, however, the 40D carries a Live View LCD that allows users to gauge focus on a small television rather than in the viewfinder box. The difference is significant. Users can magnify the subject up to 10x on screen, displaying an enlarged, visible detail of the subject. For manual focusing, we found the live view immensely beneficial. At 10x, however, it can be difficult to keep the camera steady enough for it to be effective without a tripod.

Exposure (9.0)
The 40D offers a variety of exposure controls. It has Program, Shutter Priority, Aperture Priority, and Manual modes. The Program mode can be shifted, allowing users to select the desired shutter speed/aperture combination.

Exposure compensation can be adjusted up or down 3 stops in 1/3 or 1/2 stops. The 30D, the 40D’s predecessor, can only be adjusted 2 stops.

Metering (8.25)
The camera has a 35-zone TTL system with the following metering options: evaluative (linked to the selected autofocus point), partial (meters from 9 percent of the frame), spot (meters from 3.8 percent of the frame), and center-weighted average.

White Balance (9.25)
Like the 30D, the 40D has daylight, shade, cloudy, tungsten, white fluorescent, and flash white balance presets. The custom white balance setting allows users to manually select a color temperature from 2,500 to 10,000K.

There are white balance bracketing and white balance shift features. White balance bracketing writes three files to the memory card with variations in white balance +/- 3 levels, in full stops. White balance can be fine tuned +/- 9 levels along the blue/amber and magenta/green axis.

ISO (8.75)
The Canon 40D has a 100-1600 ISO range, with the option to expand it to 3200 ISO. ISO can be adjusted in 1/3 or full-step increments. Auto ISO is now also available in Creative Zone modes.

Shutter Speed (9.0)
The 1/8000 to 30-second shutter speed range is adjustable in 1/3-step increments. There is also a bulb setting for longer exposures. The shutter speeds allow users to capture everything from sports action to star-lit skies. The 40D has a maximum sync speed of 1/250.

Aperture (0.0)
Aperture is adjusted in 1/2 or 1/3 stops when a compatible EF, EF-S, TS-E, or MP-E lens is attached to the camera.