Sony Cyber-shot RX100 Digital Camera Review$649.99
Behavior of the noise reduction algorithm is a little unpredictable. Baseline noise rates begin at 0.70% at ISO 80, which is actually a little high for this price tag. Noise increases steadily from there, eventually touching 1.27% at ISO 400. At this point, the smoothing software kicks into high gear and becomes much more aggressive. As a result, noise actually drops down at ISO 800, and begins its slow climb once again, this time to a maximum of 1.51% at ISO 6400.
The distinct behavior of the noise reduction software does not directly translate into real world image quality. So although the algorithm becomes more aggressive at ISO 800, image quality doesn't take an unacceptable hit until ISO 1600. In general, noise manifests itself as pixelation, rather than grain or color splotching, and this is characteristic of many Sony cameras, especially compacts. More on how we test noise.
The RX100's ISO range is somewhat unusual. The lowest part of the range goes in third-stops: we get ISO 80, then 100, then 125. After that, ISO proceeds in regular full stops, before maxing out at 6400. No extended options are available. Auto ISO meters from ISO 125 to 3200.
Focus is usually reliable and moderately fast, however there are some issues with real-world usage that will crop up from time to time. First, minimum focus distance is rather strict when you're zoomed in. The problem is alleviated at the closest focal length, but for portrait photography you'll need to back up to a reasonable distance. Second, the f/1.8 lens is capable of producing an in-focus area that's so narrow you may have trouble keeping your subject inside it after locking focus, especially while hand-holding. A decent way around this is to use continuous autofocus in conjunction with subject tracking.
Video: Low Light Sensitivity
The RX100 has exceptional low light sensitivity. In order to gather 50 IRE of image data, the sensor requires only 3 lux of ambient light. This must be partly the result of the camera's huge aperture, and puts performance on par with the best prosumer camcorders.
This of course explains the strong low light sharpness score 60 lux is barely a challenge for this camera.