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.
Noise due to ISO is very low in the D40x. At ISO 100 and ISO 200, noise is almost nonexistent. At ISO 400, it begins to become noticeable on monitors and only ever-so-slightly softens the image, but doesn't appreciably detract from prints. Even at ISO 800, you can barely see noise in prints, and though it is apparent on monitors, it's still well under control and images are still very pleasing. At ISO 1600, noise is more pronounced still, but you should be able to get pleasing prints; images retain much of their shadow detail, and while finer details are softened, they aren't obliterated--text that was readable at ISO 100 will still likely be readable at ISO 1600. At the camera's Hi1 setting, noise becomes very prominent, finer details become blurred away, and the overall dynamic range becomes truncated so you lose a fair amount of shadow detail. However, you should still be able to produce passable prints if you stick with smaller sizes.
Nikon's D40x is a very impressive camera. While not quite as fast as the Canon Rebel XT, it does offer a higher resolution, though the Rebel is less expensive. If you're considering the D40x with the 18mm-135mm kit lens, and you've shot with an SLR before, you'll probably prefer the control system of the D80, which also includes a coupling pin, so you can use it with older Nikon AF lenses and retain the autofocus capability. If you're stepping up to your first dSLR and don't have a stash of old lenses, the D40x is a good choice.