Overall, photos from the SD4500 IS are very good, putting it on par with the ISO performance of (Sony's Cyber-shot HX5V, which is another compact megazoom that uses a backside-illuminated CMOS sensor. My biggest issue 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 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 for smaller prints and Web use at its highest ISOs. (View larger.)
Handheld Night Scene mode rapidly takes several shots and then processes them together into a single photo with reduced noise and blur from hand shake. On the left is a photo taken in Auto; the photo on the right is taken with Handheld Night Scene mode. You'll have to enlarge the photo to really see the difference, but the mode does appear to reduce noise. However, it does not seem to help with blur. The camera used a shutter speed of 1/15 second and ISO 1,000 for both photos. Since you're only going to be using this mode for stationary subjects, my suggestion is to take a couple in Auto and take a couple in this mode and see which you prefer. It really depends on the individual scene and conditions on which will be most successful.
The burst-shooting speed of this camera is one of its biggest selling points and it works well. The camera can continuously capture photos at 3.6 frames per second with the focus and exposure set with the first shot. There are faster burst modes on other BSI CMOS cameras, but they typically keep you waiting while they store the shots to your memory card, potentially causing you to miss photo opportunities. The Canon saves while you shoot, so you're only waiting 2 to 3 seconds after you release the shutter button before you can shoot again. Also, there is the option to have it autofocus with each photo, but that will slow you down to just less than 1fps. (View larger.)
Continuous shooting for the most part is only available in Program mode. If you want a fully automatic mode, you'll have to switch to the camera's High-speed Burst mode that captures 2.5-megapixel photos at up to 8.8fps. This is a 100 percent crop of one of those photos. The results are decent for small prints and Web use with little or no cropping. (View larger.)
There is minor barrel distortion at the camera lens' wide angle (top). There doesn't seem to be any pincushioning at the telephoto end (bottom). Sharpness is good edge to edge with only a slight amount of softening in the corners and 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 for a top-of-the-line camera, I expect less. Though it's mostly visible at 100 percent, such as around the white number and striping on the black shirt, it has the potential to change the color of a subject. (View larger.)
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 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. 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.
After seeing so many wide-angle compact megazooms in 2010, the 36mm-equivalent lens on the SD4500 IS is disappointing (top). It does make the telephoto end of the 10x zoom a little more impressive though, especially for such a small camera.