White Balance

As well as the default auto setting, the S5i has six white balance presets (daylight, cloudy, shade, tungsten, fluorescent W and fluorescent D) and a manual/custom setting that can be used with a white or gray card to accurately measure the color of light in a scene. Our standard studio tests showed the S5i to be fairly reliable, and real-world shots rarely suffer from white balance problems though inevitably in low incandescent lighting there is a strong orange color cast).

Outdoor - Auto WB
Red -1.1%, Blue 2.1%

Fluorescent - Auto WB
Red 0.1%, Blue -1.4
Incandescent - Auto WB
Red 4.4%, Blue -5.3%

Flash Performance

No real complaints here. The range is acceptable for short range social shooting (around 1 to 11.5 feet at ISO 200), and color and exposure very reliable. The flash throttles down fairly well at short shooting distances, only blowing out when you get nearer than about six inches. The positioning of the flash so near to the lens means red-eye is fairly common unless you use the red-eye reduction system.

Skin tone Excellent color,
Slight overexposure
Color chart Excellent color and exposure

Macro Focus

The S5i has two macro modes; standard macro (closest focus 18cm over the entire zoom range) and super macro (closest focus around 6cm). The Super Macro mode fixes the focal length at around 62mm, but does allow some pretty impressive close ups for such a small camera. Distortion and edge softness are both admirably low.

Super macro - 46 x 34 mm coverage
55 px/mm (1407 px/in)
Distortion: Low to average
Corner softness: Low
Equiv. focal length: 62 mm
Tele macro - 61 x 46 mm coverage
42 px/mm (1059 px/in)
Distortion: low to average
Corner softness: low
Equiv. focal length: 105 mm

Barrel and Pincushion Distortion

The S5i's 35-105mm equiv. lens exhibits fairly strong barrel distortion at the wide (35mm equiv.), but at around 1.3% it's not serious enough to mar 99% of normal real-world shots. The distortion gradually falls as you move up the zoom range, but there is still a tiny amount (0.2%) of measurable barrel distortion at the long (105mm equiv.) end of the zoom range. Considering the unique sliding design of the lens distortion is very well controlled at all but the widest zoom setting.

Barrel distortion - 1.3 % at Wide angle
Equiv. focal length: 35 mm
Barrel distortion - 0.2% at Telephoto
Equiv. focal length: 105 mm

Noise Comparison

Here for visual comparison are color patches shown at 100% (actual pixels) cropped from our standard studio test shot. Although it is undeniably strong at ISO 400, the S5i controls noise fairly well (though at ISO 200 and 400 the noise reduction is so strong it obscures fine detail).

ISO 80 100% crop
0.25 sec, F4.4

ISO 100 100% crop
0.25 sec, F4.4

ISO 200 100% crop
1/5 sec, F4.4
ISO 400 100% crop
1/10 sec, F4.4

Specific image quality issues

The Optio S5i produces surprisingly good results for such a small camera, and - given the obvious compromises involved in designing for the shirt pocket - is unlikely to disappoint its target market. Exposures are generally fine, though there is a tendency to underexpose slightly, meaning most images need a touch of brightening in post processing to really make them shine. On a positive note this does mean that you're much less likely to lose highlights than with some competitor cameras. I also found the default image contrast to be a little on the high side, though there is an option to reduce contrast, which improves things somewhat. Colors are generally very natural, though perhaps a little under saturated for most tastes - again you can boost the saturation in-camera or in post processing.

All-in-all a performance that leaves little to worry about - inevitably there is a slight overall softness (though little or none of the corner softness seen, for example, in the Canon SD300), and the noise - and effects of the heavy noise reduction - means ISO 400 shots lack much fine detail, but there is much to like in the S5i's results. As with all cameras of this type you need to decide on how much of a trade-off you are prepared to accept between image quality and portability.

Color fringing

We found very little color fringing in real world shots, and where it did occur it was always in areas of overexposure, and was often combined with some blooming and burnt out highlights. Essentially color fringing is not a significant issue in the S5i shots.

100% crop 35 mm equiv., F2.6