Nikon images also benefit from the company's amazing D-Lighting feature (which I first described in a review of the D700 professional camera). D-Lighting compensates for the inherent weakness of all digital (and for that matter, film-based) cameras: They can't capture a wide dynamic range. The difference between light and dark is far narrower in a photo than in our eyes. D-lighting helps fix this by automatically brightening the dark parts of photos. Black remains black. But those murky dark-gray areas lighten up enough so that you can see the details lurking in the shadows. Of course, you can play with this in any photo editor. But if you brighten JPEGs more than a tad, you'll start getting a grainy effect because there just isn't enough data to create a sharp image. Nikons apply D-Lighting to the far more abundant RAW data before spitting out JPEGs.

Now, if you "shoot RAW" with the Canon, you have a lot more information to work with. And in tweaking the RAW files, I was able to recover a lot of detail in both the dark and light parts of the photo. But it's still easier to have the camera do the work for you. And D-Lighting is merely an option. You can turn it off completely or select from four levels of correction. And if you shoot RAW photos on the D90, you can change these setting after the fact.
The differences in color were subtler. But my preference is for the Nikon's fully saturated greens and reds. With the 50D, even objects that are deep red in real life have an orangey tint in the photos. And deep greens, like those in plants, take on a hint of yellow. Adjusting the colors in RAW didn't help. Boosting the red or the green might have improved those colors, but it added an odd tint to anything that was white.

Changing the white balance didn't help, either. As with the Nikon, I shot most photos in auto white balance. But I tried all other settings on the RAW files (which is the same as if I had shot the photos at all settings) and was unable to get a truer color balance.
This wasn't much of a surprise. Canon SLR's have had that orangey "warm" glow for years. It's often a nice effect. In portraits, for example, people with very pale skin look like they've gotten a little sun. And even pictures shot by the bluish tint of noonday sun get a bit of that "golden hour" glow that you typically see around sunrise or sunset. But you can easily tweak colors on your computer. I prefer starting with the more accurate images from the D90.

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It would have made far more sense to compare the 50D and the D300, since they are closer in both price and specs.
The 50D and the D90 are in two different categories. The D90 is basically a glorified budget model, with some admittedly nice features tossed in. For example, the 720p video recording, though it has some pretty major flaws, is at least on paper, a great bonus (although some would call it more of a gimmick than anything).
But while the D90 would likely be a lot of fun to use for most budding amateurs, it just doesn't offer the build quality or the image quality of the 50D. And anyone hoping to take serious video with it will be frustrated to no end. The 50D, of course, opts to pass on the video aspect and just stick to what DSLRs do best--and there's no doubt it's better at that than the D90. As for the apparent user-friendliness of the D90, much of this ease-of-use paradoxically comes from less flexibility, and options that are tucked neatly away to avoid confusing novice DSLR users.
My advice to anyone who is actually considering between these two cameras for their next purchase: before making a purchase, you may need to do some soul searching and decide precisely what your priorities and your needs are, and then determine whether you want to take the next step in DSLR photography. If you would prefer to remain more casual in the pursuit of your hobby, I can think of no better option than the D90. But if you're itching to step up, I would suggest the 50D is more up your alley. (However, note that from the reviews I've read, the Nikon D300 appears to be a slightly superior camera even to the 50D, so I would definitely recommend some hands-on time with both before making a final decision.) Hope this helps.
What a great comparison! It's hard to argue with actual printed results. While I've used and prefer Nikons since the S model for stills, I use and prefer Canons for video. I hardly believe that 720P is "more of a gimmick" - check out the author's indoor videos from his link. You should see what outdoor video is like!
Actually, the Rebel XSi (450D) comes closer in price and features (also a plastic body camera); same 12 MP (the Nikon is 4288 x 2848, the canon is 4272 x 2848), 3 inch diag LCD screen on both, competitive on lenses and accessories (including "smart" flash units); etc. - but the Nikon (with movie mode) is roughly $200 more street price right now.
The first comment ends with the suggestion that you spend some hands on time with the cameras and I would like to emphasize this as the most important - having good numbers doesn't mean a whole lot when you are uncomfortable with the camera for your usage (be it portraits, outdoors, macro / close ups, etc.
This is also where you look for tricks like wireless remote, and other accessories for your specific use. With computers I always stress your type of use dictates software dictates hardware; the same holds true for these cameras - your use dictates the camera you want.