Canon PowerShot S20Canon packs 3 megapixels and a 2x optical zoom into their "smallest digicam" body!<<Reference: Datasheet :(Previous) | (Next): Print-Friendly Review Version>> PowerShot S20 Sample ImagesReview First Posted: 4/4/2000 |
We've begun including links in our reviews to a Thumber-generated index page for our test shots. The Thumber data includes a host of information on the images, including shutter speed, ISO setting, compression setting, etc. Rather than clutter the page below with *all* that detail, we're posting the Thumber index so only those interested in the information need wade through it! ;) |
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Outdoor portrait: (898k) This is a tough shot for many digicams, due to the extreme tonal range (which is why we set it up this way!). The trick is to hold highlight and shadow detail without producing a "flat" picture with muddy colors and the S20 did a nice job. We shot this image using the daylight (898k) white balance setting because it produced the most accurate color and white balance results overall. The S20 did a good job with color balance, judging from the always difficult blues of the flowers and the model's pants, which it reproduced fairly accurately. (Many digicams have a tendency to reproduce these with a purplish hue). Resolution and detail also look good with only the slightest noise in shadow areas. Detail in the model's hair and the green leaves is very good. The shadow areas also look nice with a lot of detail, although we did notice blue tints on the shadow areas of the white shirt. To get the best exposure overall, we actually required a -0.3 EV adjustment to keep from getting too hot in the highlight areas on the shirt and flowers. We shot this exposure series in both the Normal and Super resolution settings, to show you the difference between the two (be forewarned, the Super setting creates huge file sizes). The table below shows the results of a range of exposure settings from -0.3 to +1.0 EV.
Exposure Compensation Series:
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Closer portrait: (899k) The S20 also does a good job with this "portrait" shot, thanks to its 2x optical zoom lens, although we did get a bit of rounding in the model's features, since the maximum equivalent focal length is only 64mm. The availability of longer focal lengths is a key feature if you're going to be shooting close-up people shots like this one, so a zoom lens really helps. For our main shot (899k), we used a -0.3 EV adjustment and the highlight areas still seem almost too hot (particularly on the sunny shirt collar). Sharpness and detail remain very crisp in both the highlight and shadow areas, still maintaining an absolutely minimal amount of noise. As with the outdoor portrait, we shot this close-up with the daylight white balance setting in both the Fine and Super resolution sizes (using the Fine setting in the main shot). We quite honestly see *no* difference between the super and fine quality modes. We opted to use the fine mode for our main shot, but include the Super versions below for those who want to get out the figurative microscope... The table below shows the results of a range of exposure settings from -0.3 to +1.0 EV in both the normal and super resolution settings.
Exposure Compensation Series:
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Indoor portrait, flash: (840k) The S20 does a good job in this category by sufficiently lighting the subject without blowing out the highlights. For our main shot, we boosted the EV to +0.7, which gave us a nice balance of light on both the subject and the background, with only a minor blue tint in the shadow areas of the white shirt. We snapped one without any exposure compensation, resulting in this (809k) very dark image with strong blue tints in the highlights. |
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Indoor portrait, no flash: (817k) This shot is a very tough test of a camera's white balance capabilities, given the strong, yellowish color cast of the household incandescent bulbs used for the lighting. The S20's white balance system did a good job here, with the incandescent (817k) setting providing the best results. (Much better than average at removing the strong yellow cast.) The automatic (803k) white balance setting resulted in a very warm image, with a marked magenta cast. For our main shot, we boosted the exposure compensation to +0.7 EV for a more balanced lighting effect. We also shot with the 200 (2540k) and 400 (2351k) ISO settings to show you the increase in noise with the gain boosted (all the other shots were taken at 100 ISO). The ISO 200 shot had increased image noise, but would probably be acceptable for many applications. At 400 ISO though, the noise becomes quite evident: No doubt useful for getting an action photo that might be badly blurred otherwise, but probably more noise than most folks would want to put up with. The table below shows a range of exposure compensation settings from zero to +1.7, shot with the incandescent white balance setting. Exposure Compensation Series:
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House shot: (2363k) NOTE that this is the "new" house shot, a much higher-resolution poster than we first used in our tests. To compare the image of the S20 with previously tested cameras, here's a shot of the original (2650k) house poster.
We shot this image with the automatic (2363k), daylight (2372k) and cloudy (2380k) white balance settings. The automatic and daylight settings produced nearly identical results, so we went with automatic as it had the best overall color balance. The cloudy setting resulted in a slightly warmer image. Excellent resolution and detail, judging by the brick and shingle areas, as well as in the shrubbery and tree limbs. The only noise we found seems to be coming from the actual poster, so camera noise is at a minimum. The S20's in-camera sharpening also does an excellent job, as we barely notice any halo effect on the light and dark edges. The table below shows the full range of resolution and quality settings for the S20.
We played with the S20's sharpness settings. The "minus" setting for sharpening appears to not totally remove the in-camera sharpening, but rather reduces it significantly. The "plus" setting definitely increases the sharpening, to a level perhaps appropriate to printing on a non photo-grade inkjet printer. Although the low sharpening option didn't completely remove the in-camera sharpening, the resulting image does nonetheless take unsharp masking in Photoshop(tm) very well. Overall, we felt that the default sharpening of the S20 did an excellent job, avoiding the heavy-handedness of some competing cameras in this respect. Sharpness Variations:
We also played with the S20's contrast variations, with the results below. Contrast Variations:
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Far-Field shot: (2629k) This image is shot at infinity to test far-field lens performance. NOTE that this image cannot be directly compared to the other "house" shot, which is a poster, shot in the studio. The rendering of detail in the poster will be very different than in this shot, and color values (and even the presence or absence of leaves on the trees!) will vary in this subject as the seasons progress. In general though, you can evaluate detail in the bricks, shingles and window detail, and in the tree branches against the sky. Compression artifacts are most likely to show in the trim along the edge of the roof, in the bricks, or in the relatively "flat" areas in the windows. NOTE: While we saw only the barest hints of it, some S20 owners have reported a tendency to shift bright blue colors markedly toward purple. We saw just the slightest tendency toward purple in the sky of our own outdoor shots, but feel we should also refer readers to this page, which shows several samples of images with rather purplish skies. That said, this is an absolutely tailor-made application for our favorite image-adjusting program PhotoGenetics: It's "IsoColor Evolution" function can develop a standardized correction for color problems of this sort, that you can then batch-apply to all your images. Although we didn't encounter the purple/blue problem to any significant extent in our own testing, we highly recommend the $45 PhotoGenetics program ($30 for the program, $15 for the IsoColor plug-in) to prospective S20 owners! The S20 does a good job with this shot. This test is the strongest test of detail and resolution of any we do. At the same time, the bright white of the central bay window is an extremely strong highlight, and often tricks digicams into losing detail in that area. Unfortunately, the S20 fell into the highlight trap, but this is about the only complaint we have. Color balance and saturation look nice overall, although we noted a slight tendency to introduce a subtle magenta cast in areas that should be pure white. Resolution looks very crisp and there's only a minor amount of noise in the shingles. We shot with both automatic (171k) and daylight (171k) white balance settings, choosing the automatic setting for our main shot (2629k) as daylight was just a shade too warm. We also played with the ISO settings, shooting at 100 (2637k), 200 (2528k) and 400 (2468k) to show the increase in the noise level. (With a maximum shutter speed of 1/750, and minimum aperture of f/8, the ISO 400 shot is badly overexposed, so it's really not particularly useful. The ISO 200 shot does show a moderate increase in noise though, although as noted earlier, probably acceptable for many users looking for just a bit faster shutter speed.) The table below shows our standard resolution/quality series.
As with the House shot, we played with the S20's sharpness settings, with the results below. Sharpness Variations:
In this shot, the contrast adjustment seemed to have much more effect on the shadows than on the highlights. We suspect the best exposure for this test would have been with the exposure compensation adjusted down by 0.7EV or so, combined with the low contrast setting. This would have preserved the strong highlights, yet not lost detail in the shadows. (Unfortunately, we didn't manage to shoot one like that as part of our testing...) Contrast Variations:
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Lens Zoom Range: We've received a number of requests from readers to take shots showing the lens focal length range of those cameras with zoom lenses. Thus, we're happy to present you here with the following series of shots, showing the field of view with respectively, the lens at full wide-angle, the lens at full telephoto and the lens at full telephoto with 2x and 4x digital telephoto enabled.
The S20's 2x optical zoom covers a narrower range of focal lengths than competitors with 3x zooms, although the lens delivers very high quality over that range. As noted in the full review, CKC Power makes an excellent lens adapter for the S20 that permits use of accessory lenses with the camera to expand the focal length range, increase macro performance, etc. The images below were all shot at the smallest file size (640 x 480 pixels) to shorten download times, which means that the digital tele here works more like a true telephoto, since you don't notice the lost resolution due to the cropping of the CCD area. If we'd shot at larger sizes, the falloff of resolution as the digital zoom engaged would be dramatically evident.
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"Musicians" poster: (2473k) As with the House shot, we shot samples of this using auto (2473k), cloudy (2471k) and daylight (2468k) white balance options. Daylight and automatic produced very similar results, with the daylight setting just a hair warmer. Cloudy produced much warmer results, leading us to choose the automatic setting for the main shot. Judging by the skin tones and the often difficult blue of the Oriental model's robe, color balance and saturation look very good. Resolution and detail also look nice, based on the subtle color variations of the bird wings and silver threads of the Oriental model's robe, although there's just a moderate amount of noise (which could partly be from the graininess of the poster itself). Below is the standard resolution and quality series as well as a contrast variation series. Resolution/Quality series:
Contrast Variations:
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Macro shot: (2498k) The S20 performs nicely in the macro category, capturing a minimum area of 2.86 x 2.14 inches (72.63 x 54.47 mm). Nice detail, sharpness and color, although the brooch seems slightly soft (possibly due to a limited depth of field). The flash (2415k) does a nice job of throttling down for this small area. The reflection of the coin often tricks many digicams and the S20 does a good job of illuminating the frame with the flash and still catching the details on the coin without washing out the image too much. The S20 also does a good job with the 2x (2249k) digital telephoto in macro mode, producing a surprisingly clear image. (Although you can easily see the significant detail loss resulting from the digital zoom if you compare this image with the main shot (2498k).) |
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"Davebox" test target: (2579k) The S20 did well in this category also. We shot with the automatic (2579k), daylight (2585k) and cloudy (2613k) white balance settings. Cloudy produced extremely warm results, as you'd probably expect. Daylight and automatic were very similar, with daylight producing just a hint of a warmer cast. Judging by the tell-tale white areas of the small resolution target, we chose automatic as the most accurate. The difficult cyan, magenta and yellow color blocks look bright and vibrant, as do the majority of the color swatches, although we felt the additive primaries (the bright red, green, and blue patches) were slightly undersaturated and weak, the blue most notably so.) The S20 does a good job of distinguishing between the red and magenta color blocks on the middle, horizontal color chart (many digicams have trouble here and try to blend the colors into one) as well as the subtle tonal variations in the Q60 chart, with the "B" range in the pastels completely visible. Detail in the shadow area of the briquettes turned out moderately well, with just a small amount of noise. The camera distinguished the large gray scale steps all the way down to step 17. We did observe a slight magenta cast to the image as a whole, most visible in the pure white areas, in which brightness values for the green channel are a couple of percent below those for the blue and red. Below is our standard resolution and quality series as well as a contrast variation series. Resolution/Quality series:
Contrast Variations:
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Low-Light Tests We were rather puzzled by the S20's low-light performance: The increased gain settings (equivalent ISO values of 200 and 400) seemed to have no effect whatever on the ultimate low-light performance we could achieve. Increasing the gain by 2 f-stops (Gain +2.0) simply decreased the exposure time proportionately. In normal and "Night" modes, the camera refused to give us an exposure time longer than 1.0 seconds, despite the manual's statement that Night mode permitted exposure times as long as 2.0 seconds. Slow-shutter mode gave us a 2 second exposure, but in the process, stopped the lens down to f/6.9, more than canceling the effect of the longer exposure time. Overall, the camera did quite well down to light levels of 1 foot-candle (about equivalent to night scene in a city, illuminated by typical street lights). At 0.5 foot-candles though, the image was unacceptably dark, and no image at all could be seen at the 0.25 foot-candle level. To its great credit though, the S20 produced no color shift at all as the light levels got lower (most digicams seem to introduce major color shifts at low light levels), and the focus-assist light makes it possible to achieve accurate focus even in complete darkness. The table below contains links to low-light exposures taken at ISO settings of 100 and 400, as well as two shot in "Night Mode." Exposure Compensation series:
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Flash Range Test (This test was added in August 1999, so cameras tested before that time won't have comparison pictures available. As we go forward though, all the new models will have similar tests available). Canon rates the S20's flash range from 6.7 inches to 10.8 feet (17cm to 3.3m) in wide angle. We found the S20's flash to be effective all the way out to 14 feet, with a slightly blue color shift beginning at 10 feet. The table below shows results obtained at a range of distances from eight to 14 feet. Flash Range/Distance:
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ISO 12233 ("WG-18") resolution target: (2654k) The S20 did remarkably well in the resolution test. We were expecting a good performance, due to the excellent detail it showed in some of our "natural" test targets, and in the very delicate in-camera sharpening it applied. We were frankly surprised though, when we saw just how well it performed in the laboratory resolution test. We were impressed with the resolution of some of the other 3 megapixel cameras we tested prior to the S20 (most notably the Nikon Coolpix 990), but the S20 clearly has even the Coolpix beat in the resolution department. The S20's resolution appears to exceed what should be possible, based solely on its pixel count, a fact we attribute to its excellent suppression of artifacts, in both the chrominance and luminance domains. We "called" the S20's resolution as 900 lines per picture height in the horizontal direction, and 850-900 in the vertical, with detail visible in both directions as far out as 1000 lines. (In the vertical direction, we could just barely see some aliasing beginning at 750 lines, but it was very minor, and easy to overlook. Aliasing was almost nonexistent in the horizontal orientation until 950-1000 lines.) This is really extraordinary. What's even more surprising is how much the image could be improved by further unsharp masking in Photoshop(tm), as seen here (1837k) (250%, 0.5 pixel radius). The lens also shows virtually no falloff of sharpness in the corners of the image, something we've become accustomed to seeing to one degree or another in most digicam images. As is commonly the case, sharpness at telephoto was slightly less than at wide angle, but the falloff really wasn't terribly significant. Really an exceptional performance! The tables below show resolution chart samples shot in both Wide Angle and Telephoto zoom settings. Resolution Series, Wide Angle:
Resolution Series, Telephoto:
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Viewfinder accuracy/flash uniformity target: We found the S20's optical viewfinder to be rather inaccurate, showing only 76 percent of the final image area in wide angle (344k) (the smaller image size, 640 x 480, produced about 68 percent accuracy) and about the same percentage (76) in telephoto (348k) (likewise for the 640 x 480 size). We also noticed that using the optical viewfinder in telephoto resulted in a shift towards the upper left corner in the final image. The LCD monitor was much more accurate, showing about 95 percent of the final image area in wide angle (332k) and about 94 percent in telephoto (334k) (the smaller image size produced the same accuracy results with the LCD finder as the larger one). To give you an idea of what we're looking for, we generally like to see LCD monitors as close to 100 percent accuracy as possible, so the S20 does a pretty good job in that respect. As to optical viewfinders, while we personally prefer greater accuracy, the industry standard seems to be about 85% accuracy. We also shot at the 2x (302k) digital telephoto setting, which produced very clear results and about 96 percent frame accuracy, and at the 4x (201k) digital telephoto setting which produced a much softer image but with a higher 98 percent frame accuracy.
Optical distortion on the S20 is fairly low, with the lens showing 0.61 percent barrel distortion at wide angle and 0.31 pincushion distortion at telephoto. The S20's 0.61% barrel distortion at wide angle is a bit less than typical, and 0.31% pincushion at telephoto is quite good. The lens also shows just the tiniest amount of chromatic aberration as we could maybe see about half a pixel's worth of color on either side of the resolution target lines in the extreme corners, a very good performance in this parameter. (This distortion is visible as a very slight colored fringe around the objects at the edges of the field of view on the resolution target). Additionally, flash uniformity looks good, with just a small bit of fall-off at the corners in wide angle. |
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