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-308), middle gray matched. We estimate the accuracy of these results to be +/- 1/6 EV (the margin of error given in the ISO specifications). We found that measured ISO from the NEX-5N matches the camera-stated ISO throughout the range (so ISO 100 = 100, etc). This means that, given identical exposure settings, the 5N at ISO 100 should give you the same result as another camera with the same rated ISO.
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.
Here, we're looking at the Sony Alpha NEX-5N's noise performance compared to three of its closest competitors, the Olympus PEN E-PL3, NEX-C3 and Nikon D3100 at default noise reduction settings.
As you can see the NEX-5N's JPEG performance in terms of noise is very near what we see from the NEX-C3 and marginally better than the Nikon D3100. At ISO settings 3200 and above the NEX-5N performs near the top of the group in chroma and grey noise reduction, producing far cleaner images than the D3100, especially at ISO 12,800.
At ISO 200 - 400 noise is well controlled and has nearly no impact on overall image quality. At around ISO 800 noticeable graininess begins to show, however detail is still mostly unaffected. Noise begins to affect critical image quality at about ISO 3200, but remains well managed all the way up to ISO 25,600. As you can see at ISO 6400 and above, the noise reduction algorithm used in the 5N is different to the one used in the C3. Rather than a convolution of noise in the C3 the 5N utilizes a more sophisticated method of noise reduction that helps to maintain the appearance of fine detail.
Sony has changed the nomenclature of it's noise-reduction settings in the 5N compared to previous NEX models. They are now listed as 'Standard' and 'Low'.
Raw noise (ACR 6.5, noise reduction set to zero)
Here we look at the raw files processed through Adobe Camera Raw (in this case version 6.5). 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 RAW mode the NEX-5N produces a nearly identical result to the NEX-C3, and performs measurably better than the Olympus PEN E-PL3, in both chrominance and luminance noise reduction at all but the lowest ISO settings where signal to noise ratio is high enough to make any noise that is there essentially invisible. In both JPEG and RAW noise management the NEX-5N is a excellent performer, rivaling many higher-end DSLR cameras.