One other note about performance: the autofocus system wasn't particularly fast, it was noticeably slow in low light, and it seemed to struggle when shooting movies.
Overall, photos from the SD4500 IS are very good and on par with the ISO performance of Sony's Cyber-shot HX5V, which is another compact megazoom that uses a BSI CMOS sensor. My biggest problem with both of these cameras is that at their lowest ISO setting (which isn't all that low at 125) photos are generally soft, not sharp. By the time you reach ISO 400 (a common setting for indoor photos), details are mushy because of the noise reduction. The Canon's edge is that its colors are consistent up to ISO 1,600, and even at ISO 3,200 they're still good, if a little washed out. That means in low lighting or when fully zoomed out or both, you'll be able to get usable shots, if even just for smaller prints and Web use at its highest ISOs.
There is minor barrel distortion at the camera lens' wide angle. There doesn't seem to be any pincushioning at the telephoto end. Sharpness is good edge-to-edge with only a slight amount of softening in the corners and at the very edges. The amount of fringing on high-contrast subjects is above average. It's certainly not uncommon to see on a compact megazoom, but from a top-of-the-line camera, I expect to see less fringing. Though it's mostly only visible when photos are viewed at 100 percent, it has the potential to change the color of a subject.
Color accuracy is excellent, producing bright and vivid results. If you like to experiment, there are options for setting color saturation, sharpness, and contrast. Exposure is generally very good, but highlights tend to blow out. BSI CMOS sensors seem to clip highlights worse than the CCD sensors found in most compact cameras. Manufacturers such as Sony have been solving this to some degree with high-dynamic range modes that will take two shots at different exposures and combine them for a more balanced shot. Unfortunately, Canon doesn't offer a mode like that on this model, and its i-Contrast feature is more for rescuing shadow detail than highlights (though that feature does work well). Lastly, auto-white balance is generally very good, though it is slightly warm indoors, whereas the custom setting used in our lab tests was cool.
Video quality is very good, slightly better than an HD pocket video camera. It won't replace a full-size camcorder, but is certainly good enough for Web use or casual viewing on an HDTV. There is noticeable judder when panning the camera or when shooting fast-moving subjects, but that's typical of video from compact cameras. You do get use of the optical zoom while recording and the lens movement is very quiet so it doesn't get picked up by the stereo mic. Lastly, the 1080p file sizes are huge; a 10-second clip came in at roughly 41MB.
The PowerShot SD4500 IS is Canon's attempt to compete with Sony's Cyber-shot HX5V and its ilk. While the Sony is definitely more polished in terms of putting the BSI CMOS sensor to use, there are things the Canon does better and in a smaller body. The SD4500 IS's lack of a wide-angle lens is a turn-off, as is its overall shooting performance, but it's the short battery life that's really the hiccup for me. If that doesn't matter to you, it's certainly a compact megazoom worth considering.
(Seconds: smaller is better)
(Frames per second: larger is better)
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