Canon PowerShot SD900 Exposure
Saturation & Hue Accuracy
Good overall color and hue accuracy, slight oversaturation in blues, undersaturation in yellows and yellow-greens.
Most consumer digital cameras produce color that's more highly saturated (more intense) than found in the original subjects. This is simply because most people like their color a bit brighter than life. The SD900 does oversaturate the red and blue tones slightly, though not nearly as bad as usual. We found its color pleasing on a wide range of typical subjects. Where oversaturation is most problematic is on Caucasian skin tones, as it's very easy for these "memory colors" to be seen as too bright, too pink, too yellow, etc. Here, the SD900 performed well, with only slight warmth.
The other important part of color rendition is hue accuracy. Hue is "what color" the color is. The SD900 showed small color shifts relative to the correct mathematical translation of colors in its subjects, but overall had more hue-accurate color than most consumer cameras we test. Oranges move toward yellow. Cyans and purples move toward blue, probably to create good sky colors.
Exposure and White Balance
Indoors, incandescent lighting
Warm casts with both Auto and Incandescent white balance settings. About average exposure compensation required.
|Auto White Balance +0.7 EV||Incandescent WB +0.7 EV|
Color balance indoors under incandescent lighting was just a bit warm and reddish in Auto white balance mode, while the Incandescent setting resulted in a more yellow color balance that actually looked more pleasing overall. The SD900 required a +0.7 EV exposure compensation boost to get a good exposure, about average for this shot. Overall color is a bit dark and yellow here, making the blue flowers very dark and purplish. (A very common outcome for this shot.) Our test lighting for this shot is a mixture of 60 and 100 watt household incandescent bulb, a pretty yellow light source, but a very common one in typical home settings here in the US.
Good color balance overall, with fairly bright colors. Heightened contrast under bright outdoor conditions.
|Auto White Balance, +0.7 EV||Auto White Balance, Auto Exposure|
Outdoor shots showed better than average exposure accuracy, though with notably high contrast under harsh sunlight. Strong highlights tended to produce slight underexposures, as in the house shot above, with a limited midtone range, but exposure accuracy was still better than average when compared to many other consumer digicams. Overall color looked pretty good, with bright reds and blues that nonetheless didn't look too overdone.
High resolution, 1,400 lines of strong detail.
|Strong detail to 1,400 lines horizontal||Strong detail to 1,400 lines vertical|
Our laboratory resolution chart revealed sharp, distinct line patterns down to about 1,400 lines per picture height, with extinction at around 2,000. (The camera produced slight color artifacts at lower line frequencies though, visible in the full-sized res target shots.) Use these numbers to compare with other cameras of similar resolution, or use them to see just what higher resolution can mean in terms of potential detail. Beware that while you might be able to make out what looks like distinct lines at numbers higher than those we've mentioned here, the camera is just doing its best to continue interpreting the lines.
Sharpness & Detail
Sharp images with excellent detail. Minor blurring of detail from noise suppression in areas of subtle contrast.
The Canon SD900's images are relatively sharp with just a little softening, probably due to noise suppression. There is little evidence of edge enhancement, however, which means that some of this softening could be recovered with a tool like unsharp mask in Photoshop. (Edge enhancement creates the illusion of sharpness by enhancing colors and tones right at the edge of a rapid transition in color or tone.)
Noise-suppression systems in digital cameras tend to flatten-out detail in areas of subtle contrast. The effects can often be seen in shots of human hair, where the individual strands are lost and an almost "watercolor" look appears. The crop at far right shows this somewhat, with both darker and lighter areas of Marti's hair showing limited, blurry detail; though individual strands are visible where a lighted strand passes in front of a darker shadow area. On balance, the SD900 shows less detail loss to noise reduction at low ISO settings than average, but more at high ISOs. This 10 megapixel sensor is relatively noisy, so noise suppression is expected.
ISO & Noise Performance
Moderate noise at the normal sensitivity settings, but very high noise and strong blurring at the higher settings, especially at ISO 1,600.
|ISO 80||ISO 100||ISO 200|
|ISO 400||ISO 800||ISO 1,600|
The SD900's lower ISO settings produced low to moderate noise, with only slightly blurred detail in the dark areas. (As noted above, better than average in this respect.) However, starting at ISO 400, image noise begins to dominate areas of fine detail, and starts to destroy skin tone, producing an unflattering purple cast. ISO 800 images are decent, not that far removed from the 400 image in terms of detail, but there's a more stippled look. At ISO 1,600, noise is so strong, blurring so significant, and the purple cast so pronounced that resulting images are not useful for printing without post-processing, except at the smallest sizes (see the Output Quality section below for more).
Extremes: Sunlit and low light tests
High resolution with good overall detail, but high contrast limits both highlight and shadow detail. Limited low-light capabilities, but sensitive enough to capture bright images under typical city street lighting.
|+0.3 EV||+0.7 EV||+1.0 EV|
Because digital cameras are more like slide film than negative film (in that they tend to have a more limited tonal range), we test them in the harshest situations to see how they handle scenes with bright highlights and dark shadows, as well as what kind of sensitivity they have in low light. The shot above is designed to mimic the very harsh, contrasty effect of direct noonday sunlight, a very tough challenge for most digital cameras. (You can read details of this test here.)
The SD900 had a hard time with the deliberately harsh lighting in the test above, producing high contrast with washed-out highlights and deep shadows. Shadow detail is limited, with the effects of noise suppression evident in the form of smudged detail in deep shadow areas. The camera required a slightly less than average amount of positive compensation at +0.7 EV, making its metering a bit more accurate than most in this particular test. (In "real life" though, be sure to use fill flash in situations like the one shown above; it's better to shoot in the shade when possible.)
The Canon PowerShot SD900 performed well on our low light test, with good color from the Auto white balance setting. At the lower ISO settings (80 and 100), images were bright down to 1/8 foot-candle, which is about 1/8 as bright as average city street lighting at night. From ISO 200 to 1,600, images were bright down to the lowest light levels we test. The camera's autofocus system also worked very well, able to focus on the subject down to the 1/8 foot-candle light level unassisted, and well past the darkest light level we test with the AF assist lamp enabled. Keep in mind that the long shutter times here absolutely demand the use of a tripod or other camera support to get sharp photos. (A useful trick is to just prop the camera on a convenient surface, and use its self-timer to release the shutter. This avoids any jiggling from your finger pressing the shutter button, and can work quite well when you don't have a tripod handy.)
Coverage and Range
A useful flash range, and moderate orange cast with incandescent lighting. Our standard shots required +0.7 EV compensation.
|37mm equivalent||111mm equivalent|
|Normal Flash, +0.7 EV||Slow-Sync Flash, +0.7 EV|
Flash coverage was rather uneven at wide angle, and still uneven at telephoto. In the Indoor test, the SD900's flash underexposed our subject at its default setting, requiring use of +0.7 EV exposure compensation to get reasonably bright results. Even here, the exposure is a little dim, with a noticeable orange cast. The Slow-Sync flash mode also needed +0.7 EV, though it resulted in more even lighting (and a stronger orange cast).
At ISO 100, flash power remained fairly bright to the 16 foot test distance at wide angle but falloff began about the 13 foot test distance with telephoto.
|Manufacturer-Specified Flash Range|
Our standard test method for flash range uses a fixed setting of ISO 100, to provide a fair basis of comparison between cameras. We also capture two shots using the manufacturer-specified camera settings, at the range the company claims for the camera, to assess the validity of their claims. In the shots above, the SD900 seems to perform exactly as Canon says it will, producing good exposures at the rated distances with its ISO set to Auto. The range is understandably limited, given the small flash and small lens, but seems to be boosting its ISO to only about 400. This produces greater flash range, but at the cost of higher image noise. In Auto ISO mode, the SD900's flash photos suffer somewhat from anti-noise processing, but are still usable at small print sizes.
Good print quality, great color, crisp prints at 11x14 inches, usable ones at 13x19. ISO 800 images are still usable at 8x10 inches and great at 5x7 and 4x6. Higher ISOs are only (barely) suitable for 4x6 inch snapshot prints.
Testing hundreds of digital cameras, we've found that you can only tell just so much about a camera's image quality by viewing its images on-screen. Ultimately, there's no substitute for printing a lot of images and examining them closely. For this reason, we now routinely print sample images from the cameras we test on our Canon i9900 studio printer, and on the Canon iP5200 here in the office. (See the Canon i9900 review for details on that model.)
The Canon SD900 produced crisp prints at 11x14 inches, and somewhat softer but still acceptable ones at 13x19. There is some evidence of chroma noise at these sizes, especially in the shadows, even at ISO 80. This is a sign that the 10 megapixel sensor is showing the flaws that we knew it would, flaws we've also seen in the Canon A640 and more in the Canon G7. As always, the real test of print size came at the higher ISO settings. Here, the SD900's ISO 400 images were soft and overprocessed when printed at 11x14 inches, but quite acceptable at 8x10 and great at 5x7 and 4x6. ISO 800 images were noisy but acceptable at 8x10. ISO 1,600 and 3,200 were acceptable at small sizes, and decent if you appreciated what they were: a shot you'd never had gotten without a tripod at the lower ISOs. They were also usable if processed with a good anti-noise filter, but only intermediate photographers will bother trying to improve these images.
Color-wise, the Canon SD900 did pretty well, with bright but natural-looking color and good-looking skin tones that go somewhat purple at higher ISOs.
Bottom line, low-ISO shots from the SD900 look very good and hold together well at large print sizes, but its high-ISO images are a little rough.