The Canon EOS 450D is the entry level camera in the Canon lineup. It has some nice improvements in comparison with the 400D - 3" LCD screen with Live View (that features contrast-detection autofocus, for the first time in a Canon DSLR), extented battery life, new menu system with customizable "My Menu". On the other hand, in spite of these steps forward, it has made two steps back: first, it has 12 MP sensor and 14 bit RAWs - that means larger file sizes without any real improvement in comparison with the 10MP, 12 bit RAWs of the 400D. 12 megapixels in the same sensor size means more noise than 400D (and the 400D was already noisier than 350D), and a small resolution advantage that you will see only if you shoot with apertures larger than f/8 (due to diffraction). And the 14 bit depth in my opinion is just marketing hype - I have not seen yet any clear proof of the its advatanteges, in particular in low-end sensors as the one of 450D.

The second step back is the burst, that has gone from the 3FPS x 10 RAW of the 400D to 3.5FPS for...just 6 RAWs; this is another negative effect of the larger file sizes. Overall, I think that it is a good camera, but it could have been better. I recommend the 450D to those who have a limited budget: if you can not spend a lot, buy the 450D and good lenses. A 450D with high quality lenses give better photos than a 5D or even 1Ds3 with average lenses!

Similar bodies: Nikon D80, Sony A200, Olympus E-510

The Canon 40D is Canon's fabolous mid range camera! I have it since few months and I love it; it has an excellent price/performances ratio. The image quality is excellent; even though it is not a step up from the 400D; the features instead are much better than 400D - it is much faster, it has live view (extremely useful for macro), and overall better built quality. If you don't have a very high budget but you want a first rate body, I recommend the 40D, in particular for wildlife photographers - the high pixel density helps to capture distant subjects, and the high speed is another bonus. The 40D is a good choice even for macro photographers, thanks to live view. If you have a mid or high budget and are interested exclusively in landscapes, instead, I'd suggest to consider a FF camera as the 5D.

Similar bodies: Nikon D300, Sony A700, Olympus E-3

The Canon 5D was a revolutionary camera when it was announced, two years ago, and it is still unparalleled. It is the only fullframe camera with a price tag around 2k, and it offers excellent image quality - high resolution and much lower noise than 40D, 400D and many other cameras. The body is good, but not better than 40D, and in terms of features it is worse - it has not live view, it has a smaller screen, it is much slower (3 FPS vs 6.5 FPS), and it lacks of many of the new features of 40D. On the other hand, the fullframe sensor allows to use the wide angles at their best - in particular, you can use lenses as the Sigma 12-24 or the Canon 15mm Fisheye to get their unique angle of view.

Similar bodies: currently there are not similar cameras!

The 1D3 is a sport and wildlife photographers dream - if it works ;-) The majority of 1D3 bodies sold between its announcement and october 2007 have AF problems; at the time of this writing, it seems that canon has finally sorted out the AF problems. The Canon 1D3 has very low noise (even tough the new Nikon D3 seems even better) and it is the only camera currently avaible that has 10FPS at 10 megapixel resolution and with AF traking. I recommend this camera to nature photographers that have an high budget and are specialized in wildlife and action. This is a camera for pro and advanced amateurs, it has a wide range of features but you need some experience to fullfill its potential.

Similar bodies: Nikon D3

In the field of nature photography, the 1Ds3 may interest mainly landscape photographers, even though the improvements in comparison with the previous versions make it much more usable as all-around camera; its speed does not come even close to the 1D3, but it is already pretty good. The features are essentially identical to the 1D3, except the burst (5 FPS instead or 10PFS) and the sensor: the fullframe, 21 megapixel sensor a dream for those who want the maximum detail and for those who often use wide-angle lenses. That said, in my opinion it is way overpriced - $ 8k is a very steep price, even for a pro. I recommed it to professionals who don't need the maximum speed and have a really high budget.

Similar bodies: currently there are not similar cameras