As noted at the outset of this
review, the Canon PowerShot S5 IS is an update of the S3 IS.
This model continues the same general design, uses the same
USM 12X stabilized zoom, and is similar ergonomically.
Three differences, however, make it a different camera. It
has a 2.5-inch hinged monitor, an 8-megapixel CCD, and the
images are handled by Canon's D!GIC III processor.
Aperture: f3.5, shutter speed: 1/20 sec.,
80 ISO.
D!GIC III is capable of processing
images faster, and adds a number of new features, such as
Face Detection and Auto ISO shift, for example.
Face Detection is very effective. Not only does the camera
recognizes that a face is in the frame, it maintains the focus
on it even if the subject is moving, and adjusts the exposure
as necessary to maintain a well exposed subject, even if flash
is required. Moreover, if the automatic red-eye reduction
system is active, it eliminates this problem effectively without
any intervention from the photographer.
Auto ISO is a function that
is activated by pressing the
button so that the camera can temporarily increase the ISO
when it is fixed at a specific value. The system makes it
possible to capture a sharp image of fast movement, or when
the ambient light is insufficient to guarantee a shutter speed
that is fast enough to prevent camera shake.
However, the S5 IS becomes quickly prone to noise, possibly
as a result of the pixel density of its CCD.
Between 80 and 100 ISO, noise is
undetectable. But, as soon as sensitivity reaches 200 ISO noise
can be detected in shadows, even when the image had the benefit
of good natural light. Sensitivities of 400 and 800 ISO reveal
a noticeable increase in noise, both in shadow areas and areas
of uniform colour such as the sky. At the 1600 ISO level, noise
is so pervasive that the image the camera yields is difficult
to use.
Still, as is often the case
with noisy images, the 400 and even 800 ISO images captured
with the S5 IS tend to be quite acceptable when reduced and
printed out to a common size such as 4 x 6 (10 x 15 cm).
Moreover, as the optical stabilization of the S5 IS is quite
excellent, it is generally unnecessary to have to increase
the sensitivity to capture a sharp image, even when the zoom
is used and the ambient light is too low.
Aperture: f4, shutter speed: 1/125 sec.,
80 ISO.
Optically, however, it would appear
that the resolution of the CCD may be butting up against the
limits of the resolving power of the lens when it is at the
wide end. Indeed, at wide focal lengths the images tend to have
a soft focus that gets even softer in the corners of the frame,
the sharpness increasing gradually as the zoom progresses towards
the telephoto end, at which point the images are tack sharp.
Aperture: f4, shutter speed: 1/640 sec.,
80 ISO.
Worth noting, however, is the fact that the lens has no serious
chromatic aberration — at most only a touch of purple
fringing can occur on the edges of very strongly contrasting
image elements — and that all other distortions are
effectively neutralized. Indeed, very minor barrelling can
be detected in some subjects when the zoom is at the wide
angle end, while there is no pincushion distortion at the
12X telephoto end of the zoom.
Similarly, the auto white balance
produces very accurate and natural colours when used outdoors.
And, not only are colours accurate, they show an excellent
level of saturation that make them snap. This said, the auto
white balance is less reliable when used under artificial
light and users should not hesitate to fall back on the custom
white balance setting, or a setting appropriate to the ambient
light source to get the best possible results.
Our principal regret with the S5 IS, however, is that it does
not offer Canon's RAW image format. While it is true that
images captured using the Super fine JPEG
image quality retain an excellent level of detail, a very
good colour range and show no sign or artifacts from the compression,
a high-end camera such as this should offer a RAW format,
so that users can take complete advantage and control over
the image quality that the S5 IS can yield.
With flash photography the S5
IS is rather well-equipped with just its built-in flash. It
has enough power to light evenly a 3 m (12 ft) room at 80
ISO. Likewise, while the red-eye effect can always occur,
the automatic red-eye correction function is very effective.
But, probably the most interesting new feature for flash photography
with the S5 IS is the fact that the camera has a flash hotshoe.
The S5 IS is compatible with E-TTL flash metering and is
compatible with Canon's Speedlites 220EX, 430EX and 580EX
II; and with one of these, the S5 IS's flash photography performance
is even better.
The Canon PowerShot S5 IS is a camera designed for advanced
amateurs, and some time is required to tame it and obtain
the highest image quality. Nevertheless, it would appear that
the 8-megapixel resolution seems to be at the limit of what
the lens can support, and with wide angle shots it is not
unusual for images to require some post capture sharpening.
Similarly, noise is a factor and the S5 IS produces its highest
image quality if sensitivity is kept to a maximum of 200 ISO.
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Image Quality
button so that the camera can temporarily increase the ISO
when it is fixed at a specific value. The system makes it
possible to capture a sharp image of fast movement, or when
the ambient light is insufficient to guarantee a shutter speed
that is fast enough to prevent camera shake. 
