Noise, Resolution and Sensitivity
With a 10.1-million-pixel compact camera sensor, the LX5 performs quite well, managing to resolve to just over 20 on our resolution test chart when the sensitivity is set between ISO 80 and 200. By ISO 400, detail resolution begins to drop and at ISO 800 the sensor can resolve up to 18. The maximum sensitivity before the resolution drops is ISO 3200 and even at this point the LX5 still resolves up to 16.
Image: Low-light exposures push the LX5 to its limit. This shot was taken at IS0 3200 and, although noisy, it is still acceptable when printed as a 6x4in image
Colour noise is well controlled throughout the entire sensitivity range, but luminance noise is visible at ISO 200 and above, and becomes progressively more obtrusive. In its default setting, the noise reduction is quite strong at ISO 1600-3200 and gives images a characteristic smudged appearance.
The shortcomings of the LX5 are fairly typical of a compact-style camera, but the fact that it has a usable sensitivity range of ISO 80-800 means that its image quality is around 1EV better than most other similar compact cameras on the market.
Left: These images show 72ppi (100% on a computer screen) sections of images of a resolution chart, captured using matching 105mm macro lenses. We show the section of the resolution chart where the camera starts to fail to reproduce the lines separately. The higher the number visible in these images, the better the camera’s detail resolution is at the specified sensitivity setting. Right: This graph shows the brightness values recorded by the test camera when it is used to photograph a stepped graduation wedge. The wedge has transmission values in 1⁄2EV steps ranging from 0 to 12EV. The camera’s exposure is set so the 12EV section in the wedge has a brightness value of 255. Software analysis of the image then determines the recorded brightness values of all the other steps and calculates the camera’s dynamic range.
