The PowerShot SD900 is among Canon's pricier Digital Elph compact cameras. For $450 (as of February 15, 2007), you get a tough, attractive titanium body equipped with a generous 10-megapixel sensor, though the camera does lack a few of the high-end features available in its siblings.
You don't get the optical image stabilization of the SD800 IS model (which costs $400); and the lens zooms to just 3X, compared to 3.8X for the SD800 IS. The SD900's 2.5-inch LCD, meanwhile, is smaller than the SD630's 3-inch screen, but it's exceptionally bright and sharp, offering a higher resolution of 230,000 pixels. It also leaves room for a small optical viewfinder, which you'll appreciate when shooting under bright lighting conditions (the SD630 lacks a viewfinder).
The controls on the right side of the camera seemed a bit cramped, but they were easy enough to use. The manual mode doesn't give you full control over the aperture and exposure settings, but it does let you customize in several ways how the camera takes your shots. You can adjust the exposure compensation to bring out highlight or shadow detail better. A nighttime mode lets you set long exposure times. You can set contrast, sharpness, and saturation independently, and a variety of color settings are available.
Like the SD800 IS, the SD900 has a face detection feature. When the camera detects human faces in the frame, it automatically selects the best focus and exposure. A green box appears around your subject's face on the LCD when you hold the shutter release halfway. If more than one person is in the shot, the camera settles on one as the most prominent and displays gray boxes around up to two others. I was surprised at how quickly it locked onto the faces of people as they walked past my table at a local cafe. Since it picks up only human faces, it's no help for cute pet pix, but it worked well for a range of skin colors. In order for the camera to detect a face, the person must be upright and looking in your direction with both eyes in view. If a face is not recognized, the camera defaults to its regular auto-focus operation. My portraits of various friends came out well, with their faces sharp and exposed correctly. Also, I managed to avoid a problem I occasionally encounter, in which the auto-focus locks onto a strongly contrasting edge in the background instead of on my intended subject.
In tests conducted by the PC World Test Center, the SD900's 10-megapixel sensor produced exceptionally sharp photos with little distortion. The camera also earned high marks for exposure accuracy, though it performed better in natural light than with a flash. Color accuracy could have been better; the SD900 received an average score for this attribute.
Turning up the ISO sensitivity or shooting with longer exposures tends to produce digital noise with random colors in the image. As an informal test, I took a few nighttime shots with the SD900 mounted on a tripod and compared them to similar shots from a digital SLR (an 8.2-megapixel Canon EOS 30D) and an older compact camera (an 8-megapixel Canon PowerShot S80), also mounted on a tripod.
I noticed significant amounts of noise in the SD900's shots as I increased its ISO sensitivity above 400, but it performed better than the S80 at the same ISO settings (the S80 tops out at ISO 400). The 30D was far superior: Its noise level at ISO 3200 was comparable to the SD900's at ISO 400. That's probably because the 30D's sensor is much larger. You'd be wise to save the SD900's higher ISO settings for when you're forced to take a low-light shot, regardless of the results. Or you could use a high ISO when you have plenty of light and want to eliminate movement by using a faster exposure time; normally, you'd simply increase the camera's shutter speed to achieve this result, but the SD900 doesn't let you adjust shutter speed.
The SD900 comes with a 32MB SD Card that can hold only about six shots at the camera's highest resolution and quality settings. However, it does accept the new SDHC memory card format, which comes in sizes of 4GB to 32GB. The included travel charger is about the same size as the camera, with prongs that fold inward for easy portability. We averaged 257 shots on a single charge of the lithium-ion battery--a bit below the average mark for cameras we've tested.
If you're looking for the greatest number of megapixels, the SD900 won't disappoint. Until Canon adds image stabilization and a longer zoom, this should remain one of the best compact point-and-shoots around.
