Distinctions between Canon's entry-level DSLRs are becoming harder to make. The 450D was very similar to the 400D, and Canon's latest, the 500D, shares the 450D's dimensions down to the millimetre, so the two cameras sit exactly the same in the hand.
Practically, the grip is a little too small to be truly comfortable, and the 732g weight means that if you use one of Canon's heavier lenses, you could find yourself with a seriously unbalanced piece of kit.
This isn't the only similarity. Both cameras have nine autofocus points and a handy ISO button in front of the shutter release. Both offer 14-bit RAW capture and shoot at nearly exactly the same continuous rate: 3.5fps on the 450D and 3.4fps on the 500D.
You even get the same kit lens: Canon's reasonable 18-55mm IS EF-S. Its image stabilisation is effective, and Canon has largely cured the purple fringing problems of the 400D.
There are a few external changes. The white balance button of the 450D now operates the 500D's Live View mode. Quickly changing the white balance is still possible, but as a result there's no longer a button to quickly access the metering mode menu.
Changing the metering mode now requires you to use the shooting settings display. The 500D also gains a Creative Auto mode, which breaks technical terms such as depth of field and aperture into simpler language such as Background: Blurred/Sharp.
All significant changes are internal. Where the 450D had a maximum ISO setting of 1600, the 500D goes up to 3200 by default. And, by making a minor change in the Custom Settings menu, you can push the ISO as far as 12800, although images taken at this setting were ruined by noise. You also get the inevitable resolution bump, from 12 megapixels on the 450D to 15.1.
The most important change is the image processor. The 450D used Canon's DIGIC III processor; the 500D uses the DIGIC 4 - the same as you get in the professional 5D Mark II.
This means little in terms of image quality: the 450D took superb pictures and so does the 500D, ultra-high ISO mode notwithstanding. However, the DIGIC 4 processor adds H.264 video encoding.
The 500D is the only Canon DSLR to offer video except the 5D Mark II, and offers both 1080p and 720p recording. 1080p is frustrating, though, as the 500D can muster only 20fps in this mode. 720p mode is glorious, however: a full 30fps and great video quality for a device at this price.
Our test videos looked superb: well-balanced colours, lots of detail, and the ability to switch lenses is a feature missing from all but the most expensive semi-professional camcorders.
We criticised the Nikon D90 for being able to record clips to a maximum of only five minutes, but the 500D can record for up to 29mins 59secs, or to a maximum file size of 4GB. It's a great feature: we frequently found ourselves framing shots in still mode and then cracking and recording a ten-second HD vignette to go with it.
But video isn't without frustrations. As with all DSLRs, the 500D's focus sensor is separate from the CMOS image sensor, and as such the 500D can't focus well while the mirror is snapped up and video is being recorded.
Instead, you either have to use contrast detection focusing, which is comparatively inaccurate and, depending on the lens, horribly loud; or you can have the mirror snap down, the dedicated focus sensor do its work, and then have the mirror snap back up, which creates a break in video. The integrated mic is no headline-maker, as it's mono-only and you can't plug in your own unit.
At least manual focusing works brilliantly. At first glance, the 500D's screen is the same as that of the 450D: 3in diagonal. But, like the 5D Mark II and Nikon D90, it has 920,000 pixels - four times the resolution of the 450D. This means that image and video playback looks stunning: the screen is bright and reproduces colours well. It also means it's easy to tell if a frame is focused in live view and video modes.
This luxury may be responsible for the 500D's decreased battery life. Where the 450D could manage around 500 shots before running out of batteries, the 500D shoots about 100 fewer. If you shoot a lot of video, battery life is worse still: you can at least buy Canon's BG-E5 battery grip, which allows you to use two lithium-ion batteries at once.
But even with excellent video quality and expanded ISO range, the 500D struggles to justify the price increase over the 450D. Since its launch, the 450D has dropped to around $1000: the 500D costs $1400. And that's before you consider the Nikon D90, which costs $1400 and offers a superior lens, better handling and 4.5fps continuous shooting to the 500D's 3.4.
If you want an HD-capable DSLR and are put off by the D90's five-minute shooting, the 500D is currently your only choice without having to consider the 5D Mark II. But you'll have to be certain you'll use it for video before splashing the extra cash.