Sony DSC-S90

Reviewed July 2005

Image Quality

Characteristics such as a 3X zoom and a 4-megapixel resolution position the Sony DSC-S90 in the middle of a very crowded and competitive field. Nowadays, 4-megapixel is almost entry-level, and a 3X zoom is the standard.

So, to make the S90 stand out from the crowd, Sony has given it Carl Zeiss optics, a 2.5-inch LCD monitor, and a Manual shooting mode that makes it possible to capture long exposures, a feature not commonly found with cameras in this price range.

The Carl Zeiss zoom yields good outdoor images with a high level of detail and which show very little distortion, either with wide angle or telephoto shots.

At the wide angle end the barrel distortion is well-corrected and only becomes recognizable when the subject is nearby and vertical or horizontal lines are placed close to the edges of the frame. At the telephoto end, distortion is even better managed, and it normally impossible to detect.

Given the right circumstances, however, such as when a dark object is imaged against a bright white sky, or when the image is overexposed, a purple line can become visible along the boundary between light and dark, signalling a chromatic aberration.

Without changing any of the default settings of the S90, the camera produces high quality images that have rich and vibrant colours. Greens and reds are particularly precise, and nature shots emphasize this strength, reproducing a myriad green hues easily, a testament to the precision of the Auto white balance.

Metering is also reliable even under adverse conditions, something we experienced first hand during this test of the S90.

The default metering pattern of the camera evaluates a number of areas in the frame and assembles each of the these readings into an average that takes into account one or more focus points. The resulting images are usually well-exposed and take into account highlights and shadow areas, turning out an image that rarely shows any trace of over- or underexposure.

To a great extent, the image sharpness produced by any camera is directly related to its lens. But, with digital cameras another factor generally comes into play: the compression applied to the image to save it.

In the case of the Sony DSC-S90 two image quality levels are provided. Fine, which uses the least amount of compression, usually applies a compression ratio that hovers in the neighbourhood of 6.7:1, allowing subtle details in the image to stay part of the image.

Standard, the alternative setting is useable, but applies a compression that seems to be often more than twice that of the Fine level, and which can lead to a noticeable softening of sharpness by slight blurring the smaller details.

Generally, noise is minimal at the lower ISO sensitivities of 80 and 100 ISO. Increasing sensitivity to 200, noise become visible, but if the subject is well-lit, and the image quality is set to Fine, noise is well within acceptable margins. At 400 ISO however, noise is quite noticeable, be it in shadow areas or in areas that contains large sections of the same colour.

Still, while wide-angle flash shots are usually acceptable, telephoto flash shots which have a maximum aperture of f5.2 tend to be too dark. Moreover, going to the menu to increase the flash's output, or to add exposure compensation, or combining both, has little effect.

To brighten telephoto flash photos, the only effective method is to set the sensitivity to Auto, which lets the camera increase it up to 320 ISO, but which by the same token also visibly increases the amount of noise in the image.