Canon 40D vs Nikon D90 - Our Analysis
The Nikon wins on multiple metrics that REALLY matter:
better AF system, and better DYNAMIC RANGE being the two key aspects, as well as
better color depth for the Nikon, the Nikon shoots
movie clips (the D90 was the very,very FIRST d-slr that did that, so it is not as good a movie-shooter as much newer cameras), and the Nikon has
better HIGH-ISO color and higher-ISO capability standard, plus
about 20% more megapixels. The 40D is already multiple generations behind the curve...the D90 is still plugging along as a very capable, satisfying enthusiasts's camera that is now available VERY affordably,both new, as well as used. Honestly, I am NOT very impressed with ANY crop body Canon that Canon has released until the EOS 60D...Canon slipped into a very bad period from 2007 to 2011, in which they failed to innovate, and just started regurgitating last night's dinner, over and over, while the NEWLY-HIRED Nikon senior executive team had a fire lit under their collective butts, and REALLY worked diligently to release a series of excellent "shooters". And this is not just my opinion...this failure to innovate was also noted by #1 Canon fan Michael Reichmann, at The Luminous Landscape...who criticized what he called Canon's "failure to innovate" on multiple occasions. The EOS 40D is a good example of failure to innovate...it was stale when it hit the shelves, as was the 50D...
For those who disagree that the 40D is/was "stale"...LOOK at the color-blind flash and color-blind ambient light metering it has, the primitive flash metering it has, and the lack of multi-flash built-in commander. Nikon kicks Canon's a$$ in ALL those categories, with the D90.