Canon S90 Exposure

Saturation & Hue Accuracy
Good overall color and hue accuracy, with moderate oversaturation of some colors.

Saturation. The Canon S90 produced good saturation overall, with moderate oversaturation in reds, greens, browns and blues. Some other colors such as bright yellows and cyans were actually undersaturated a small amount. Overall, the Canon S90's images appeared to have natural looking color that wasn't too vivid, but you can always adjust saturation to your liking. 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.

Skin tones. Here, with the color balanced properly for the light source, the Canon S90's skin tones did have a slightly pink cast, but should still be pleasing to most consumers. 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.

Hue. The Canon PowerShot S90 produced a few color shifts relative to the correct mathematical translation of colors in its subjects, most visibly pushing cyan way towards blue (for better-looking skies), red toward orange, and yellow toward green. Still, despite the shifts in red through yellow and cyans, overall hue accuracy was quite good. Hue is "what color" the color is.

Saturation Adjustment
The Canon S90 lets you adjust the image Saturation, Contrast, and Sharpness (as well as Red, Green, Blue, and Skin Tone settings) in five steps each. As can be seen below, the saturation adjustment was pretty effective. It also leaves the image contrast relatively unaffected, which is as it should be.

The table above shows results with the default as well as the two "extreme" saturation settings. Click on any thumbnail above, then click again to see the full-sized image.

Exposure and White Balance

Indoors, incandescent lighting
Good color with both Auto and Manual white balance settings. About average positive exposure compensation required.

Color balance indoors under incandescent lighting had a very slight magenta cast with the Auto white balance setting, but the Canon S90 did much better here than the majority of digital cameras we test. The Incandescent white balance option resulted in a fairly strong reddish cast, while the Manual setting produced the most accurate color overall. The Auto setting wasn't far off the mark, though. The S90's exposure system handled this lighting well, producing good results with an average amount of exposure compensation, + 0.3 EV. Overall color looks good, though the blue flowers look a touch purplish, probably due to the S90's tendency to punch up reds a little. (Many digital cameras reproduce the blue flowers here with more of a purplish tint, so the Canon S90 actually performs a good bit better than average here.) Our test lighting for this shot is a mixture of 60 and 100 watt household incandescent bulbs, a pretty yellow light source, but a very common one in typical home settings here in the U.S.

Outdoors, daylight
Good overall performance outdoors, though high contrast and hot highlights. Good color as well.

The Canon PowerShot S90 performed reasonably well under harsh outdoor lighting, though contrast was quite high. Slightly higher than average exposure compensation (+1.0 EV) was needed to keep the model's facial skin tones bright, resulting in a lot of blown highlights in her shirt and flowers. There was slight overexposure in the outdoor far-field house shot at the default exposure. Overall color is good though, if slightly reddish, with the Manual white balance setting on the portrait (the Auto and Daylight settings were just a touch too cool). Though overall contrast is high, the shadows hold onto a fair amount of detail. Fortunately, there's a contrast adjustment to help tame the highlights a bit, though it works better at bringing out shadows.

See full set of test images with explanations
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Resolution
High resolution, 1,400 ~ 1,500 lines of strong detail from JPEGs, 1,600 from converted RAW files.

Our laboratory resolution chart revealed sharp, distinct line patterns down to about 1,500 lines per picture height in the horizontal direction, and 1,400 lines per picture height in the vertical direction. (Some might argue for over 1,800 lines, but artifacts begin to appear at much lower resolutions.) Extinction of the pattern occurred between 2,100 and 2,400 lines. We were able to extract a bit more resolution from Adobe Camera Raw 5.6b converted RAW files, about 1,600 lines both horizontally and vertically. 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.

See full set of test images with explanations
See thumbnails of all test and gallery images

Sharpness & Detail
Fairly sharp, detailed images overall, with only minor edge-enhancement on high-contrast subjects. Noise suppression limits definition in low contrast areas, even at relatively low ISO settings.

Sharpness. The Canon PowerShot S90 captures very good detail and fairly sharp JPEG images. Only slight enhancement artifacts are visible on high-contrast subjects such as the crop above left. Edge enhancement creates the illusion of sharpness by enhancing colors and tones right at the edge of a rapid transition in color or tone.

Detail. The crop above right shows moderate noise suppression, as the low contrast areas of hair show less distinct detail. However, many individual strands remain fairly well defined, so performance here is actually better than average for a compact. 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.

RAW vs In-Camera JPEGs
As noted above, the Canon S90 produces fairly sharp, detailed in-camera JPEGs. We saw quite a bit more detail on the strongly contrasting geometric patterns of our resolution target when we converted images from RAW files using Adobe Camera Raw. In the natural image below, though, processing from RAW brought relatively little improvement in visible detail. Take a look below, to see what we mean:

In the table above, mousing over a link at the bottom will load the corresponding crop in the area above, and clicking on the link will load the full resolution image. Canon's Digital Photo Professional (version 3.7.1.1) software was able to extract slightly more detail, as was Adobe Camera Raw 5.6 beta, though they both produced more sharpening artifacts than the camera's default settings, and neither resulted in the sort of dramatic improvement we see with some cameras. For ACR converted RAW files, we found that Canon S90 files required strong but tight sharpening. We used Photoshop to sharpen, with USM of 500% and Radius of 0.3 pixels.

ISO & Noise Performance
Low noise at the normal sensitivity settings, with pretty good results up to ISO 400. Strong noise and loss of detail at higher settings, however.

Like the Canon G11, the PowerShot S90 produced low to moderate noise at the lower sensitivity settings, though the effects of noise reduction such as smudging and loss of fine detail can already be seen even at the lowest ISO. Fine detail holds pretty strong up to ISO 200, though. At ISO 400, noise is still reasonable and a lot of fine detail remains intact, but additional smudging is evident. Noise grain isn't really more apparent as you move to ISO 800, but stronger noise reduction results in additional detail loss. Yellow and purple blotches (chroma noise) begin to appear in darker tones and hair at ISO 800, and worsen as ISO goes up. At ISOs 1,600 and 3,200, artifacts from noise reduction and increased chroma noise dominate, blurring out most fine detail. On-screen crops like this tell you only part of the story with a camera, though: To see how these images held up when printing at various sizes, read the Output Quality section below.

Many readers will no doubt be curious how the Canon S90 compares to its larger, more expensive sibling, the G11, as well as to Panasonic's LX3. See the crops and graph below.

As you can see from the crops above, the Canon S90 offers similar noise and detail levels relative to the G11. (The difference in color is due to different white balance settings.)  The Panasonic LX3 applies less noise reduction than either of the Canons, and while its images are noisier, they also hold more detail at higher ISOs, at least in these on-screen views.

One thing that's very clearly going on here is that the LX3 is applying much more in-camera sharpening to its images than do the Canon G11 and S90. This both increases apparent detail and emphasizes noise. Let's take a look at what happens when we sharpen the S90's images to a roughly equivalent level:

The Canon PowerShot S90's high-iso images take quite a lot of sharpening, at a fairly large radius, to match the appearance of the LX3's files. At 270% and a 1 pixel radius in Adobe Photoshop, the S90 crop above now shows similar detail compared to the LX3, but with considerably finer-grained image noise.

This result was borne out by our printed tests. See the Print Quality section below for the details, but we found the Canon S90's high-ISO images straight from the camera very soft. Applying strong, large-radius sharpening to its ISO 1,600 images made for really surprisingly good prints at 8x10 inches, though. On that basis, the Canon S90's printed output significantly edged out the LX3. (It's worth repeating here that it's virtually impossible to judge print quality with any reliability without studying actual prints: Images that look horrible on-screen 1:1 often appear just fine when printed at 8x10 or below. Likewise, other images may look pretty good on-screen, but display glaring flaws in print. As always, we encourage our readers to download our test images (for their own personal use), and print them out themselves, to obtain a true sense of each camera's image quality.)

The crops above are from images shot under incandescent lighting, a particularly difficult light source for achieving low noise images at high ISOs. Let's see how detail compares under simulated daylight:

The story is similar under simulated daylight. The Canon PowerShot S90 has similar noise characteristics to the G11, with just slightly stronger noise reduction. Both have a noticeable noise advantage over the Panasonic LX3 at higher ISOs, but the Panasonic LX3 shows more visible detail in its camera-generated JPEGs. Sharpening the S90's images to overcome the softness of the original camera JPEGs brings its noise levels way up, but the noise is also very fine-grained, so modest-sized prints (8x10 inches at ISO 1,600, 5x7 inches at ISO 3,200) end up looking very nice.

The crops above show a different part of the image, to reveal both fine detail and shadow noise. The softness of the Canon S90's unaltered JPEG images at ISO 1,600 is quite evident in the leftmost crop. The center crop shows better fine detail than the LX3, yet noise levels are somewhat lower. We wouldn't use nearly this much sharpening for an image viewed solely on-screen, but when printed at ~8x10 inches, the results are really excellent.

A nice feature of the LX3 is adjustable NR, so you can make the trade-off between noise and detail yourself. The shots above were all captured with the LX3's default noise reduction setting. When we tested the LX3, we shot a noise reduction series (showing results from all available settings) at ISO 800; feeling that that was about its limit for reasonable-sized prints.

If you want to control the noise/detail/sharpness trade-offs with the Canon S90 or G11, you'll ultimately need to work from its RAW files using software. (Which does give you a lot more control than any in-camera settings, albeit with the added work of using RAW conversion software.) As seen above, though, you actually have a fair range of choice in that trade-off, simply by choosing how much post-capture sharpening you want to apply to its JPEG files.

The plot above shows how the three cameras discussed above compare in terms of luminance noise across ISO ranges in daylight-balanced lighting, as reported by Imatest. As you can see, noise levels from the S90 are very similar to the G11, albeit slightly lower due to stronger noise reduction. The LX3 has similar noise levels up to ISO 400. At higher ISOs, the LX3 shows much higher noise.

We were a little surprised to see that noise reduction was stronger on the Canon S90 vs the G11, expecting them to be identical. The crops above show how the red cloth is rendered at ISO 1600. As you can see, the G11 has left more subtle detail than the S90.

Extremes: Sunlit and low light tests
High resolution with strong detail, but high contrast. Very good low-light performance, capable of getting bright images in near darkness.

Sunlight. The Canon PowerShot S90 performed reasonably well under the deliberately harsh lighting in the test above, but with washed-out highlights and deep shadows. Despite some noise suppression in the shadow areas, detail is still good in the shadows. Highlight detail is compromised, with clipping occurring in the shirt and some flowers. At +0.7 EV, the face, background and some shadow areas are just a little dark, so we preferred the +1.0 EV exposure, though it resulted in a lot of blown highlights. The S90's adjustable contrast setting did a good job of decreasing the overall contrast and bringing up the shadows and midtones, without creating any strange color gradations on the face. Be sure to use fill flash in situations like the one shown above; and it's better to shoot in the shade when possible.

Contrast Adjustment
As mentioned previously, the camera's contrast adjustment helped in handling dark shadows, but was less effective with strong highlights.

At its lowest contrast setting, the Canon S90 did a better job of holding more detail in the shadows while maintaining fairly natural-looking skin tones in the portrait shot above. It did not help much with the blown highlights in the far-field house shot, though shadow detail is better.

The shots above show the results of the minimum, default and maximum contrast settings. While you can see the extremes, it's pretty hard to evaluate small differences in contrast on small thumbnails like these, click on any thumbnail to go to the full-size image.

The above images show the effect of the Canon S90's Intelligent Contrast (i-Contrast) feature. The Auto mode did brighten the model's face quite a bit, as well as shadow areas and the background, though exposure is still a tad dim. Still, very good results here.

The above images show the effect of the Canon S90's face detection autofocus mode (Face AiAF), which also adjusts exposure and white balance to optimize exposure for faces. The S90's face detection AF mode did adjust exposure so that the model's face is much brighter than with it Off, but as a result the rest of the scene became a bit too bright overall, losing a lot of detail in the highlights. Still, a handy feature, if you're dealing with strong backlighting, etc.

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.)

Low light. The Canon PowerShot S90 performed well on the low-light test, capturing reasonably bright images at the lowest light level all the way down to ISO 200, close to the lowest sensitivity setting. At ISOs 80 and 100, the images at 1/16 foot-candle are a bit dim, due to the S90's maximum exposure time of 15 seconds (reported in the EXIF file header as 16s), but still usable. Color balance was pretty good with the Auto white balance setting, just slightly cool. Images were reasonably clean up to ISO 400 at the lowest light levels, but naturally, noise increases along with. In addition to applying high ISO noise reduction by default, the S90 automatically applies dark-frame subtraction for exposures 1.3 seconds or slower.

The camera's autofocus system worked very well, as it was able to focus on the subject down to just below 1/16 foot-candle light level unassisted, and in complete darkness with the AF assist enabled. The PowerShot S90's relatively fast f/2.0-4.9 lens helped here. (A useful trick when shooting under dim lighting 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. With its ability to focus in very dim lighting, the S90 should do quite well in such situations.)

How bright is this? The one foot-candle light level that this test begins at roughly corresponds to the brightness of typical city street-lighting at night. Cameras performing well at that level should be able to snap good-looking photos of street-lit scenes.

NOTE: This low light test is conducted with a stationary subject, and the camera mounted on a sturdy tripod. Most digital cameras will fail miserably when faced with a moving subject in dim lighting. (For example, a child's ballet recital or a holiday pageant in a gymnasium.) For such applications, you may have better luck with a digital SLR camera, but even there, you'll likely need to set the focus manually. For information and reviews on digital SLRs, refer to our SLR review index page.

Coverage and Range
Good flash power for its size, with uneven coverage at wide-angle. Some issues with Flash exposure compensation.

Coverage and Exposure. Flash coverage was very uneven at wide-angle (not surprising, given the wider-than-average 28mm equivalent focal length), with much more uniform results at full telephoto. In the Indoor test, the Canon S90's flash underexposed our subject at its default setting, and flash exposure compensation seemed to work in reverse in Normal flash mode, with higher values resulting in dimmer results. The brightest results were at 0 EV, but the resulting image was still a bit dim. The camera's Slow-Sync flash mode produced slightly dim results at the default exposure as well. Using +1.0 EV flash exposure compensation produced the brightest exposure for Slow-Sync mode, though it was still a bit dim, and had a strong yellow-orange cast from the room lighting.

ISO 100 Range. At wide-angle and ISO 100, flash shots started out bright, peaked in brightness at about 9 feet, and remained fairly bright out to about 13 feet. At telephoto, flash shots were dim already at 6 feet, decreasing in brightness from that point on.

Manufacturer Specified Flash Test. In the shots above, the Canon S90 performs as Canon says it will at full wide-angle and telephoto, however it boosted sensitivity by quite a bit to ISO 500 to achieve these results. Our standard test method for flash range uses a fixed setting of ISO 100, to provide a fair basis of comparison between cameras. We've now also begun shooting two shots using the manufacturer-specified camera settings, at the range the company claims for the camera, to assess the validity of the specific claims.

Print Quality
Good print quality, good color, sharp 13x19-inch prints. ISO 400 images are soft but usable at 13x19, ISO 800 shots are usable at 11x14, and ISO 3,200 shots are usable at 5x7.

Print quality is quite excellent from the Canon S90's images, with good color. ISO 80, 100, and 200 shots are usable if a little soft at 16x20 inches but get quite crisp when printed at 13x19 inches. Even ISO 400 shots are usable at 13x19 but are a tad soft, sharpening up more at 11x14.

ISO 800 shots are usable at 11x14 when viewed from a distance, but appear soft on close inspection. They come back into usefulness at Letter size (8.5x11). Or, if you sharpen them a bit as I did on the G11 to match the relative oversharpening on the Panasonic LX3, they look great at 11x14.

Comparing shots from the Canon S90 with those from the Panasonic LX3, we discovered just how the LX3 gets such impressive printed results at this ISO setting. The LX3's high-ISO shots actually look pretty bad on-screen, with quite a bit of noise and very coarse-looking details. Printed, though, they look surprisingly good. What became apparent as we studied images from the two competing cameras was that the LX3's files had a lot of pretty large-radius sharpening applied to them. On-screen, they look really over-sharpened, but printed at 8.5x11 inches, they looked quite good. Applying similar over-sharpening to the Canon S90's images (1.0 pixel radius, 200%) produces similar-looking results on-screen, but excellent results on the prints as well, producing great-looking Letter size prints. With no processing, the Canon S90's ISO 1,600 images make slightly soft 8x10-inch prints.

ISO 3,200 prints look good at 5x7, if a little soft, but sharpened as described above, they're remarkably good.

This is a slightly better performance overall than the Canon G11 gave.

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 Pro9000 Mark II studio printer, and on the Canon Pixma MP610 here in the office. (See the Canon Pixma Pro9000 Mark II review for details on that model.)