Casio Exilim EX-S100

Reviewed April 2005

Image Quality

In this small space Casio squeezes a 2.8X optical zoom, a battery, a memory card slot and a 3.2 megapixel CCD that easily produces good-looking 4 x 6 prints.

Remarkably, although the zoom retracts into an approximately 1.5 cm (0.58 inch) space, wide angle photos show very little barrel distortion, while at the other end of the focal range telephoto shots are entirely free of pincushion distortion.

However, packaging a 2.8X zoom into such a thin space seems to exact a penalty on the brightness of the lens which only has 2 apertures that are, at the widest angle, f4 and f8. And the fact that the lens is not very bright impacts the camera in two areas: telephoto exposures and flash photos.

This means that at the telephoto end, the brightest aperture becomes f6.6 while the other becomes f13.3, neither of which allow for high shutter speeds as these apertures are fairly small.

The impact on the shutter speed of this limited aperture range is not usually noticeable with photos captured using the wide angle end of the zoom, which at f4 is bright enough to allow a shutter speed that is fast enough to prevent camera shake.

But at the telephoto setting, the maximum aperture of f6.6 often means that the shutter speed drops to counteract the fact that there is not a lot of light reaching the sensor. Moreover, if the camera's sensitivity is set to 50 ISO, a sensitivity level that minimizes noise, the shutter speed can become low enough to potentially cause a blurred image due to camera shake. In other words, the telephoto end of the EX-S100's zoom is best used when there is plenty of daylight, and when the subject is relatively bright or brightly lit. Otherwise, the photographer should have a very steady hand, or the camera should be stabilized to ensure a sharp image.

Similarly, zoom shots captured with the flash tend to be a bit dark as the flash's limited power has difficulty providing a sufficient amount of light to overcome an f6.6 aperture, particularly if the sensitivity of the camera is at its lowest setting of 50 ISO.

The alternative is to set the sensitivity to Auto, which allows the camera to boost it up to 200 ISO, and therefore capture a brighter image. The drawback, of course, is that the photos are visibly noisier.

Indeed, with the EX-S100 noise creeps into the images starting at 200 ISO and, if enabled, the Flash Assist feature that increases the brightness of photos captured with the flash, further emphasizes the noise captured at 200 ISO.

Regrettably, flash photography is not the EX-S100's strongest point, and in general photos tend to be either a bit dark or a bit noisy.

Aside from this limitation however, the images produced by the EX-S100 are usually quite good. Photos captured with natural light, even on a cloudy day, and with the sensitivity set to 50 ISO, which is effectively noise-free, are bright and exhibit excellent colours.

In large part, this good image quality with outdoor shots is due to the EX-S100's metering — a multi-segment pattern — that is reliable and effective at taking both highlights and shadows into account.

For another, the fact that the lens is sharp, avoids any chromatic aberration and that it is effectively free of distortion helps ensure that for this type of photography, the images the EX-S100 produces are on par with many other compact 3-megapixel cameras.

As with other comparable cameras, the EX-S100's small size entails a trade-off in terms of the variety of subjects the camera can handle. But that has to be accepted if the portability of the camera is a primary consideration.