ISO Accuracy

The actual sensitivity of each indicated ISO is measured using the same shots as are used to measure ISO noise levels, we simply compare the exposure for each shot to the metered light level (using a calibrated Sekonic L-358), middle gray matched. We estimate the accuracy of these results to be +/- 1/6 EV (the margin of error given in the ISO specifications). Note that these tests are based on the sRGB JPEG output of the cameras, in accordance with ISO 12232:2006, the standard used by camera manufacturers. In our tests we found that measured ISOs from the RX100 III are approximately 1/3 stop under-sensitive, meaning ISO 125 indicated = ISO 100 measured.

Noise and Noise Reduction (JPEG)

This is our standard studio scene comparison shot taken from exactly the same tripod position. Lighting: daylight simulation, >98% CRI. Crops are 100%. Ambient temperature was approximately 22°C (~72°F).

Note: this page features our new interactive noise comparison widget. By default, we show you the default noise reduction settings of the camera tested, and three other models of the same class. You can select from all available NR options, and from other cameras. The 'tricolor' patches beneath the familiar gray/black/portrait images are taken from the same test chart, and show how noise impacts upon blue, green and red areas of a scene.

The RX100 III shows a very similar noise progression with ISO compared to its sibling, the RX100 II, albeit with slightly lower noise reduction (NR) when both cameras have NR set to 'Normal'. The Canon G1 X Mark II and Panasonic GM1 show better detail retention at higher ISOs due to their larger sensors. However, do note that this difference will be somewhat mitigated when normalized comparisons are made to adjust for resolution differences between the cameras. The reason the G1 X II and GM1 look somewhat noisier at high ISOs when compared to the RX100 III / II in these comparisons is simply due to the lower levels of noise reduction (visible if you click on 'Graph').

NR Settings

The Sony RX100 III, like the RX10, offers a NR 'Off' mode, which was not available on the earlier RX100 models. This is a welcome addition, as the heavy-handed NR at high ISOs, even at the 'Low' setting, tends to readily smudge low contrast detail. The difference it makes is shown in the graphs below.

The aggressive noise reduction is easily visible in the drastic drop in standard deviation - visible in the graph above - as NR is engaged. However, we should point out that the measurements are so high to begin with because of the relatively high resolution considering the sensor size (and our analysis is pixel-level). Increasing NR to 'Normal' drops the standard deviations even further. If you switch over to the 'Samples' tab, you'll see the effects of the aggressive noise reduction. While it's effective at reducing visible noise in even toned patches at high ISOs, low contrast detail in the stamp is completely wiped out.

It's likely that Sony is applying such high levels of noise reduction because of its confidence in its context-sensitive NR algorithms, and because of the camera's relatively small pixels (which increases pixel-level noise). If you're sensitive to excessive NR, we'd recommend keeping it set to low. Alternatively, consider turning it off altogether in-camera, and doing your own context-sensitive noise reduction in post-processing using more sophisticated software.