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ISO / Sensitivity accuracyThe 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.
This means the GF1 is having to use shutter speeds one third of a stop faster than the other cameras on test in order to give the same overall image brightness. The NX10 meanwhile, isn't quite as sensitive at its ISO 3200 setting as it should be, so needs shutter speed one third of a stop longer. ISO Sensitivity / Noise levelsISO equivalence on a digital camera is the ability to increase the sensitivity of the sensor. This works by turning up the "volume" (gain) on the sensor's signal amplifiers (remember the sensor is an analogue device). By amplifying the signal you also amplify the noise which becomes more visible at higher ISO's. Many modern cameras also employ noise reduction and / or sharpness reduction at higher sensitivities.To measure noise levels we take a sequence of images of a GretagMacBeth ColorChecker chart (controlled artificial daylight lighting). The exposure is matched to the ISO (ie. ISO 200, 1/200 sec for consistency of exposure between cameras). The image sequence is run through our own proprietary noise measurement tool (version 1.5 in this review). Click here for more information. Room temperature is approximately 22°C (~72°F), simulated daylight lighting. Samsung NX10 vs Nikon D5000 vs Canon EOS 550D/T2i vs Panasonic DMC-GF1
The NX10 comfortably keeps pace with its APS-C peers (the EOS 550D/Rebel T2i and Nikon D5000) all the was up to ISO 800. At ISO 1600 its noise reduction is significantly reducing it in detail compared with the Canon, though it's still on a par with the Nikon. Only at ISO 3200 does it really fall behind, with large blotches of chroma noise and splodgy noise reduction removing all the fine detail. It's a little harder to compare to the GF1, given how different an approach the two cameras take to noise reduction - the Panasonic doesn't suppress luminance noise to nearly the same degree but retains more detail as a result. In terms of detail, the Samsung doesn't appear to offer any great advantages at high ISO. Noise graphs
Measured ISO sensitivity is on the horizontal axis of this graph, standard deviation of luminosity on the vertical axis. The graphs tell the same story that the image crops began - the Samsung does very well until ISO 1600, at which point both the noise really starts rising. It's worth bearing in mind, though, that although the Panasonic is showing higher noise figures, it's also retaining considerably more detail. Because the Samsung has more pixels than the Nikon or Panasonic, noise would be still lower when considered on a whole-image basis. RAW noiseRaw noise compared (ACR)We use a standard raw converter (Adobe Camera Raw usually, as it is often the first third-party software to offer support for new cameras), in order to provide a comparatively level playing field. We can't be sure ACR is doing exactly the same thing to all files but its more neutral than using the manufacturers' software (which is often based on the same algorithms as their in-camera processing). Noise reduction is set as low as possible
RAW Noise graphs
In RAW the NX10 is rather less convincing - producing more noise than ever other camera here. This means it's having to apply greater levels of noise reduction to achieve the low noise measurements shown in its JPEGs. |
