Digital Cameras - Canon PowerShot S1 IS Test Images
|I've begun including links in our reviews to a Thumber-generated index page for the test shots. The Thumber data includes a host of information on the images, including shutter speed, ISOsetting, compression setting, etc. Rather than clutter the page below with *all*that detail, we're posting the Thumber index so only those interested inthe information need wade through it!|
The extreme tonal range of this image makes it a tough shot for many digicams, which is precisely why I set it up this way, and why I shoot it with no fill flash or reflector to open the shadows. The object is to hold both highlight and shadow detail without producing a "flat" picture with muddy colors, and the PowerShot S1 IS handled the challenge fairly well, albeit with somewhat high contrast.
The shot at right was taken with a +0.3 EV exposure compensation adjustment, which still lost some detail in the highlights, even though the midtones were a bit darker than I'd have preferred. The camera's Low Contrast setting helped tone things down, but still resulted in slightly dark midtones and lost highlights. I chose the Manual white balance as the most accurate overall, though the shot was slightly warm. I preferred the warmer skin tones to the cooler, slightly magenta tints of the Auto and Daylight settings.
As I mentioned, skin tones are just a bit on the yellow side from the slight warm cast, but still natural-looking. The blue flowers in the bouquet are dark, but without any strong purplish tints. (Many digicams have trouble with this blue, which is in reality a pretty pure, light navy blue.) Saturation is good throughout the frame, though the red flowers appear a little too saturated (but not enough to obscure too much detail). Resolution is high, with a lot of fine detail visible in the flower bouquet and in Marti's face. Shadow detail is moderate, with a moderate level of noise. Overall, an excellent result, if only the contrast level were a bit lower. (Kudos to Canon for including a contrast adjustment, I just wish it's effect extended lower.)
To view the entire exposure series from zero to +1.3 EV, see files S1OUTMP0.HTM
through S1OUTMP4.HTM on the thumbnail index page.
Higher resolution and detail, but once again high contrast and darker midtones.
Like the wider shot above, contrast is again slightly high here, with somewhat dark midtones and a loss of detail in the brightest highlights. The shot at right was again taken with a +0.3 EV exposure compensation adjustment, although it resulted in a somewhat brighter exposure here than in the shot above. The S1 IS's 10x zoom lens avoids distortion in Marti's features, an important feature in close-up shots like this. Detail and resolution are stronger in this shot, with good definition in Marti's face and hair, as well as in the house siding. Noise is again moderate in the shadows, obscuring shadow detail slightly.
To view the entire exposure series from -0.3 to +1.0 EV, see files S1FACM1.HTM
through S1FACP3.HTM on the thumbnail index page.
Indoor Portrait, Flash:
Good intensity and coverage with the built-in flash, with good color at the normal setting.
The S1 IS' built-in flash illuminated the subject very well here, even
at its default exposure setting (although it
was just a bit dim with its default setting). I found the best exposure
with a +0.7 EV exposure compensation adjustment,
which produced good coverage and accurate color. Color looks quite good
overall, although the blue flowers are a bit darker than in real life.
The camera's Slow-Sync flash mode resulted
in a strong yellow-orange cast from the background incandescent lighting
and longer exposure, but the flash coverage is good and a little more
even than in the normal flash mode.
I chose an exposure compensation setting of
+0.7 EV for this shot as well.
For the same exposure series in the Slow-Sync flash
mode, see files S1INFSP0.HTM through S1INFSP4.HTM.
Indoor Portrait, No Flash:
Good color with Incandescent and Manual white balance options. Moderate noise.
This shot is always a very tough test of a camera's white balance capability, given the strong, yellowish color cast of the household incandescent bulbs used for the lighting. The S1 IS' Auto white balance fell victim to this trap, producing a very warm image. The Incandescent and Manual white balance settings produced more accurate results, the Incandescent option producing a slightly cool-toned image, the manual option a slightly warm-toned one. While I generally prefer a slight warm cast on this shot, to evoke the mood of the original room lighting, I found myself liking the image shot with the Incandescent setting the best, and so chose it for the main shot for this test. The shot at right was taken with a +1.0 EV exposure compensation adjustment, which is a bit dim. The overall exposure was brighter with a +1.3 EV adjustment, but I felt that the highlights on the white shirt were too hot and distracting. The blue flowers in the bouquet are dark and purplish, but that's probably to be expected given the tough lighting.
Good overall color, despite slight color casts, and great detail.
Though slightly cool, I found the S1 IS's Manual
white balance to be the most accurate here, with the best white value
on the house trim. The Auto and Daylight
settings also produced good color, though with a slight warm cast. (It's
really personal preference between the Manual and Auto settings, as some
people may prefer the warmer tint of the Auto white balance.) The Cloudy
setting produced a stronger warm cast, but not dramatically. Resolution
is high, and detail is strong in the tree limbs and front shrubbery, as
well as in the brick pattern. Details are also reasonably sharp throughout
the frame, without any strong softening in the corners.
Great resolution and detail, though exposure is high and dynamic range limited.
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.
This is my ultimate "resolution shot," given the infinite range of detail in a natural scene like this, and the S1 IS performed very well. Detail is strong in the tree limbs over the roof and fine foliage in front of the house, with pretty good definition in the finer details of the tree bark and leaves. Details are quite sharp and well-defined across the image, without any noticeable softness in the corners. (This is quite unusual, in my experience.) The bright sunlight on the bay window causes the camera to lose all but the strongest details here, a trouble spot for many digicams. (I should also point out that the exposure is just slightly bright, which contributes to the loss of highlight detail.) Detail is slightly better in the shadow area above the front door. Still, the S1 IS's dynamic range is a little limited by its somewhat high native contrast. The camera's Automatic white balance setting produces good color, though saturation is low from the overexposure. The tables below show a standard resolution and quality series, followed by ISO, sharpness, contrast, saturation, and effects series.Resolution Series:
Lens Zoom Range
An excellent 10x zoom range.
I routinely shoot this series of images to show the field of view for each camera, with the lens at full wide angle, at maximum telephoto (10x, in this case), and at full telephoto with the digital zoom enabled. The S1 IS' lens is equivalent to a 38-380mm zoom on a 35mm camera. That corresponds to a moderate wide angle to a pretty substantial telephoto. Following are the results at each zoom setting.
Slight color casts, but good results overall. High resolution and detail.
This shot is often a tough test for digicams, as the abundance of blue
in the composition frequently tricks white balance systems into producing
a warm color balance. As with the House poster, this shot is again up
to personal taste. The Manual white balance
setting produces a cool color balance with pale skin tones, but I still
found it preferable to the warmer, more yellow Auto
setting. (Here is a situation where post-capture editing on a computer
would likely fix the problem.) The Daylight
resulted in warm color balance, with stronger yellow tints. The blue robe
is a bit magenta, with some purplish tints in the deep shadows. Resolution
is excellent, with great definition in the embroidery of the blue robe,
as well as on the finer details of the models.
Very good macro performance, with good detail. However, the flash is blocked by the lens and doesn't throttle down enough.
The S1 IS did quite well in the macro category, capturing a minimum area
of 2.17 x 1.63 inches (55 x 41 millimeters). Resolution is high, and fine
detail is strong in the dollar bill and coins. However, the coins and
brooch were soft due to the very short shooting distance. (Not at all
the camera's fault, depth of field is very shallow in extreme closeups
like this.) A small amount of softness is noticeable in the corners along
the left side of the frame, but it doesn't seem too bad. The S1 IS' flash
is partially blocked by the lens, and doesn't throttle down for the macro
"Davebox" Test Target
Slight overexposure, but good color.
I chose the Manual white balance setting for this shot, though the Auto setting also produced good results. (The Daylight option produced a slight warm cast.) As with a few cameras recently, I boosted the exposure compensation by +0.3 EV here to get the white block on the MacBeth(tm) target closer to the maximum white value, but in hindsight, I think the image looks a little bright overall with this exposure. Still, the camera manages to distinguish the subtle tonal variations of the Q60 target well. Aside from being just slightly washed out by the minor overexposure, colors are quite accurate in the large color blocks, although I found the red and blue additive primary color blocks just slightly oversaturated. Also, the shadow area of the charcoal briquettes shows only moderate detail, with moderate noise as well. (Once again, I wish the S1 IS's default contrast was a little lower.) Overall though, the S1 IS's color is quite pleasing.
Good low-light performance, with good color and low noise. No AF-assist light, but focuses down to 1/4 foot-candle anyway.
The S1 IS produced clear, bright images down to the 1/16 foot-candle (0.67 lux) limit of my test, with good color at the 100, 200, and 400 ISO settings. At ISO 50, results were good as low as 1/8 foot-candle (1.3 lux), though you could arguably still use the image taken at the 1/16 foot-candle light level. Noise levels remained pretty good, even at the ISO 400 setting. Though noise is high at ISO 400, it is lower than I actually expected it to be here. Color remains good even at the dimmest light levels, without any strong color casts. The surprising part though, was that the S1 IS has no AF-assist light.(!) This is particularly surprising because Canon is a manufacturer that really pioneered the use of AF-assist lighting across their product range some years back. Despite the lack of AF-assist, the camera will still focus (albeit very slowly) down to about 1/4 foot-candle, a light level roughly one-quarter that of typical city street lighting at night. This isn't bad, but the camera is obviously capable of taking pictures under much darker conditions. (Fortunately, the manual-focus scale does show numeric distance values, so you should be able to guesstimate the focus closely enough much of the time.) The table below shows the best exposure I was able to obtain for each of a range of illumination levels. Images in this table (like all sample photos) are untouched, exactly as they came from the camera.
(Note: If you'd like to use a light meter to check light levels for subjects you might be interested in shooting, a light level of one foot-candle corresponds to a normal exposure of two seconds at f/2.8 and ISO 100.)
Flash Range Test
Slight underexposure, but good consistency and range.
In my testing, the S1 IS's flash illuminated the test target all the way out to 14 feet, without any significant decrease in intensity. Flash power is slightly dim overall, but pretty consistent through the series. Below is the flash range series, with distances from eight to 14 feet from the target.
Good resolution, 1,000 lines of "strong detail." (More, with artifacts.) Average barrel distortion, but very low pincushion.
The S1 IS performed well on the "laboratory" resolution test chart. It started showing artifacts in the test patterns at resolutions as low as 600-650 lines per picture height, in both horizontal and vertical directions. I found "strong detail" out to at least 1,000 lines, although you could argue for as high as 1,200 horizontally. I chose to rate it at the lower 1,000 line number though, due to the level of moire artifacts that are present beyond that point. (I tend to rate cameras more conservatively than some reviewers.) "Extinction" of the target patterns occurred around 1,300 lines.
Optical distortion on the S1 IS is a bit better than average at the wide-angle end, where I measured approximately 0.7 percent barrel distortion. The telephoto end fared much better, as I found only 0.09 percent pincushion distortion (about two pixels) there. Chromatic aberration is moderate at wide angle, where there is only relatively faint coloration around the target elements in the corners, but fairly strong with the lens at its telephoto setting, with rather bright red/green fringes visible in the corners. (This distortion is visible as a slight colored fringe around the objects at the edges of the field of view on the resolution target.)
Resolution Series, Wide Angle
Resolution Test, Telephoto
Viewfinder Accuracy/Flash Uniformity
Excellent accuracy from the electronic viewfinder.
The S1 IS' electronic "optical" viewfinder (EVF) is very
accurate, showing 99 percent frame accuracy at both wide angle and telephoto
zoom settings. The LCD monitor is also very accurate, since it shows
the same view, just on a larger screen. Given that I like LCD monitors
to be as close to 100 percent accuracy as possible, the S1 IS's LCD
monitor is almost perfect in that regard. Flash distribution is fairly
even at wide angle, with only a hint of falloff at the corners and edges
of the frame. At telephoto, flash distribution is more uniform, but
very dim because of the shooting distance. (Nearly 20 feet or so, with
a 10x zoom camera like the S1 IS.)
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