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).
In our tests we found that measured ISOs from the Nikon D5200 matches the marked ISOs within 1/6 stop accuracy, meaning ISO 100 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.
Compared to its predecessor the D5100, the D5200 gives very similar levels of visual noise at its low and medium ISO settings, but above ISO 6400, the D5200's images are noticeably smoother. In terms of noise, there's not much to choose between the D5200 and its closest competitors the Canon Rebel T4i and Sony SLT-A57 but the higher pixel count of the D5200 does result in fractionally more detail at ISO 12,800 and 25,600.
Looking at the graph view, the D5100 and D5200 show similar noise levels up to ISO 3200. Based on the graph data alone, the Sony SLT-A57 shows impressive noise performance but it's important to note that this is due to very agressive noise reduction. You can see in the 'samples' view, especially at ISO 6400 and above, that the cost of this suppression is distinctly hazy output. Even with its noise reduction set to 'low' the A57's output is pretty mushy above ISO 3200.
ACR Raw noise (v 7.4, noise reduction set to zero)
Here we look at the Raw files processed through Adobe Camera Raw (in this case version 7.4). Images are brightness matched and processed with all noise reduction options set to zero. Adobe does a degree of noise reduction even when the user-controlled NR is turned off.
The amount of NR applied 'under the hood' is not high, but it does vary by camera (Adobe is attempting to normalize output across different sensors), so inevitably we are still looking at a balance of noise and noise reduction, rather than pure noise levels. However, the use of the most popular third-party RAW converter is intended to give a photographically relevant result, rather than simply comparing sensor performance in an abstract manner.
In the Raw mode samples above, the differences between the D5200's image quality and that of the three other cameras selected here are much more subtle than the JPEG comparisons. Up to ISO 3200 there isn't much to choose between them from the point of view of critical image quality. The D5200's 24MP sensor gives more detail though, although the difference between the Nikon and Canon's T4i isn't as great as the 6MP disparity in pixel count might suggest. The Canon holds its own until ISO 12800, where noise swamps detail to the point where the 24MP D5200 just has the edge in terms of detail reproduction (but only just).
Up through ISO 1600, there is little in terms of detail retention to separate the D5200 from its peers. Beginning at ISO 3200, however, the D5200 sacrifices less detail to chroma noise than either the Sony SLT-A57 or Canon T4i. At the camera's extended ISO settings (12,800 and 25,600) the dropoff in detail becomes pronounced, with the maximum ISO sensitivity obscuring significant portions of the image sample.