While Nikon's not alone in putting a 3-point autofocus system in its entry-level dSLRs (Olympus' E410 and E510 also use 3-point systems), some competitors, such as Canon's Rebel XTi (9-point AF) and Pentax's K100D and K110D (11-point AF) include more sophisticated autofocus systems. In our field tests, the D40x had occasional difficulty locking on subjects, sometimes choosing the wrong object, but more often was just a bit sluggish. In other areas, the D40x surpasses some of the competition. Its sensitivity settings range from ISO 100 to ISO 1600, plus an H1 setting, which is essentially equivalent to ISO 3200. By contrast, the D40's lowest sensitivity is ISO 200, as are the Pentaxes'. Canon's XTi and the two Olympuses start at ISO 100, but top out at ISO 1600. Shutter speeds on the D40x range from 30 seconds to 1/4000 second, and exposure compensation covers a rather wide swath of plus or minus 5EV in third-stop increments. However, the scale used to show exposure compensation in the viewfinder and on the LCD screen only covers plus or minus 2EV, so beyond that, you need to pay attention to the tiny numerical indicator next to the scale. All other exposure controls also run in third-stop increments, as opposed to the more-coarse half-stop increments that some cameras, such as the Fujifilm S3 Pro, use.
As always, Nikon includes its barely useful Picture Project RAW processing software with the D40x and expects you to shell out an extra $150 to purchase the company's Capture NX software if you want a more robust way to process RAW images. That means, if you plan on shooting in RAW, you need to add $150 to the price of this camera when drawing comparisons with its competitors, all of which include decent RAW converters at no charge. I have yet to meet a Nikon photographer who is not affiliated with the company who doesn't complain voraciously about Nikon's stance on this issue, but it doesn't seem as though the company will change its mind anytime soon. On the flip side, the Capture NX software is quite nice and includes some innovative image editing tools.
In our lab tests, the D40x yielded impressive results. It took 0.15 second to start up and capture its first JPEG. Subsequent JPEGs took 0.48 second between shots with the flash turned off and 0.85 second between shots with the flash turned on. The time between capturing RAW images measured 0.75 second. Shutter lag measured 0.4 second in our high-contrast test, which mimics bright shooting conditions, and 0.9 second in our low-contrast test, which mimics dim shooting conditions. In continuous shooting mode, we were able to capture JPEGs at an average of 2.97 frames per second, regardless of image size.
Image quality from the D40x is extremely good. Colors look very accurate and are well-saturated without being oversaturated. Images have a wide dynamic range, with plenty of detail in both shadows and highlights. We shot our lab test images with the 18mm-to-55mm kit lens, which produced admirably sharp images for an entry-level kit lens, though we did see a very minor amount of fringing with this lens around some extreme highlights. The camera's automatic white balance produces slightly warm images when used with incandescent light sources, such as a living room lamp, but the tungsten preset serves up neutral images in those circumstances. We got the most neutral results when using the manual white balance setting. The D40x's built-in flash is rather powerful--Nikon rates it to be effective to 39 feet at ISO 100--and it did a nice job of balancing its fill flash with the ambient light of the lamp in our test scene.