Fujifilm has given the FinePix Z90 a practical sensitivity range of ISO100-ISO3200. At the lower ISO setting images are clear and sharp; detail is held well, but pixel smearing and noise starts to appear from ISO 1600 and I would avoid going above this unless absolutely essential.
Fortunately, with care, hand-held shots can be taken at 1/8sec at full zoom thanks to the Digital Image Stabilisation, avoiding the need for the highest ISO settings on most occasions.
Image dynamic range is well controlled, but highlight clipping can occur as the standard evaluative meter leans toward rendering images on the bright side. This is easily remedied by locking the exposure with a half press of the shutter button before recomposing the shot.
Fujifilm has done an excellent job of controlling chromatic aberration in the FinePix Z90 and only areas of extreme contrast produce minor colour fringing, but it was not as prevalent as I would have expected for this class of camera.
Unfortunately, if chromatic aberration is taken care of well, lens distortion is not. Under some circumstances barrel distortion at the widest lens setting and pincushion at the longest can be a distraction and Fujifilm could have done more to improve this.
Ease of use is important for a camera in this class and unsurprisingly the auto-white balance system gives accurate results, consistently out performing the six pre-sets that are also available.
Standard, Chrome (Fujifilm colour slide film), black and white and Sepia are the four pre-set colour choices available. Black and white mode produces nice punchy images whilst Sepia gives a novelty feel. Of the two colour settings, the best overall colour results were produced in the Standard setting, and I'd suggest the camera is left at this for colour. Chrome increases blue and green saturation and contrast, but some shots have an unnatural looking greens and a cyan hue.
Overall the FinePix Z90 produces good images and these can be improved further with careful use of the available settings.