Although it is quite compact
and has a large 2.5-inch LCD monitor that takes up most of
its back, the Optio S7 has a surprisingly practical and functional
ergonomic design that goes a long way to making it quite attractive
as an easy-to-carry "pocket camera".
The S7 powers up relatively fast — it is ready to shoot
in under 2 seconds — and when used outdoors with good
light focuses quickly, both of which are valuable characteristics
for a point and shoot.
The 3X zoom has a focal length
range that is equivalent to 37.5 to 112.5 mm in the 35 mm
format. This is a range that falls in the middle of what is
offered by many compacts. It is well-suited to people and
portrait photography, but is a bit short at the telephoto
end, and only provides an average width field of view at the
wide end.
Similarly, while some compacts
offer bright apertures throughout their zoom range, the small
lens of the S7 only offers a bright (f2.7) aperture at the
wide end. At the telephoto end the brightest aperture is only
f5.2, precluding the use of the lowest ISO value, 50 ISO,
unless there is lots of bright sunlight as otherwise the shutter
speed drops to a point where camera shake is inevitable. When
bright light is not available, one alternative is to set the
sensitivity to Auto, and let the camera adjust the CCD sensitivity
over its range of 50 to 400 ISO.
Still, the S7 is biased towards
a preference for low ISO settings to avoid noise, and even
when set to Auto ISO images can be blurred by camera shake
as the shutter speed can be quite low.
The other alternative is to use the Blur Reduction Mode(see photo above). The mode extends the sensitivity
range up to 1600 ISO, while limiting the image size to 4-megapixel,
(2304 x 1728 pixels).
Set to Auto, the camera will
select a higher sensitivity but is only slightly more aggressive
at maintaining a fast shutter speed than it is in the standard
Auto ISO setting. It offers, however, the user the choice
of selecting a specific ISO setting, limiting it for instance
to 400 ISO. Indeed, at 800 or 1600 ISO photos — even
when captured under excellent light — the level of noise
captured requires noise reduction, and the processing noticeably
reduces the image sharpness (see image at right), making
the images useable when their size is reduced .
Section shown above in the red rectangle, seen here
at 100%.
Indeed, as is the case with a
number of other compacts, noise can easily creep into the
S7's photos, and shots captured under diffused or overcast
skies, even at 50 ISO, can show shadow noise when they are
examined at full size on a monitor.
Interestingly, there is no
serious increase in noise at 100 ISO, but it does become more
readily detectable as of 200 ISO, a setting often used by
the Auto ISO system when the telephoto end of the zoom is
used, or when the flash is used to boost its effectiveness.
With the higher setting of 400 ISO, noise is easily visible
and gives the image a marbled appearance that seriously undermines
its usefulness, and which is even more pronounced when shot
indoors using the flash.
Still, while noise can be seen in
images scrutinized on a monitor at their full size, printing
these same images out to standard photo print sizes, 4x6 or
5x7, eliminates most of the noise as the image size is reduced.
In fact, the Optio S7's full resolution of 7-megapixel is able
to produce a 10.24 x 7.68 inch print at 300 dpi; while a 7 x
5.25 inch print will generate a dpi of 438.8, ensuring a sharp
image.
The Pentax Optio S7 provides
3 compression levels, represented as stars, with the highest
image quality shown as 3 stars. At this quality setting, the
compression ratio is approximately 8:1, a level that can soften
the finer details of an image, and which occasionally emphasizes
noise when a high ISO setting was used.
Nevertheless, given bright light the image quality is quite
good, and this is in no small part due to the fact that the
lens is sharp, producing a crisp distortion-free image from
corner to corner, at all focal lengths.
As is the case with so many
other compact cameras, the built-in flash has a limited range
and is most effective if the sensitivity is set to Auto ISO.
Otherwise, at the lowest ISO settings of 50 or 100 ISO, the
flash can only light a subject that is 1.5 to 2 m (5 to 6.5
ft) from the camera. Nevertheless, set to Forced On,
the flash is sufficiently powerful to provide fill light for
portraits outdoors, and yields good results.
With this camera, Pentax also implements Fotonation's face
tracking technology.
Face tracking is selected as part
of the AF settings in the menu, and is a type of continuous
focus mode. The system places a target area on the monitor,
and once the shutter release is pressed halfway to focus on
the subject, the camera will automatically track the face —
in fact any area that it has focused on — when it moves,
as long as the movement is not too quick.
Like many other compact cameras
on the market nowadays, the Optio S7 is noticeably sensitive
to noise, and at the highest image quality uses a compression
that is stronger than we would prefer to see; both facets of
a camera's image quality that are most noticeable when the images
are seen at 100% size. This said, just like many others, once
The Optio S7's images are printed, the flaws that are visible
on a monitor, tend to disappear.
Image Quality
