DxOMark review for the Sony Alpha 850Thursday August 27 2009 Sensor Review
Sony was the first brand to deliver a very high resolution full-frame camera with the Sony Alpha 900. They now add the Sony Alpha 850. Although this is a new camera, it has the same resolution, the same body, and the same ISP as the Sony Alpha 900. In short, the announced differences seem very slight between these two twins.
DxOMark Sensor analysis shows that as far as sensor is concerned, the two cameras are indeed very similar, if not identical. The Sony A850 obtains the same DxOMark Sensor score (78.9)
Key sensor characteristics
The Sony A850 features a 24.5 Mpix CMOS sensor, which is the highest resolution for full-frame sensors currently available.
Key performance factors
The global performance of the Sony A850 is comparable to the Sony Alpha 900. It remains near the top for every DxOMark Sensor metric: very high Color Depth (23.8, 8th in DxOMark rankings), Dynamic Range (12.2, 12th in DxOMark rankings), and a good Low-Light ISO score of 1415 (8th place).
In comparison with other full-frame sensors, it is worth noting that the Low-Light score for the Sony Alpha twins is a bit low. Thus a final image shot at high ISO settings could be slightly noisier than those taken with other full-frame sensors.
Just as for the Sony Alpha 900, noise autocorrelation shows that the Sony Alpha 850’s RAW data has been processed before RAW is actually delivered by the camera, even if denoising options are switched off. The green channel does not seem affected by this denoising. The DxOMark scores for the Sony Alpha 850 are not impacted by noise processing.
3D view of the autocorrelation of the red channel ISO 100. The expected peak has been smoothed by noise reduction filtering (which explains the larger base of the peak).
3D view of the autocorrelation of the green channel ISO 100. As shown by the single peak (denoting white noise only), the A850’s noise reduction filtering is too low to influence DxOMark measurement.
3D view of the autocorrelation of the blue channel ISO 100. As with the red channel, noise reduction filtering smoothed the expected single peak.
Such noise removal processing can seriously increase the visual aspect of low frequency chroma noise after raw conversion, especially for high ISO, depending on how the RAW converter takes this denoising into account. The limiting resolution can decrease, too, and some small details can be lost.
Disclaimer: This dxomark review evaluates only the selected camera’s RAW sensor performance metrics (i.e., Color Depth, Dynamic Range, and Low-Light ISO), and should not be construed as a review of the camera’s overall performance, as it does not address such other important criteria as image signal processing, mechanical robustness, ease of use, flexibility, optics, value for money, etc. While RAW sensor performance is critically important, it is not the only factor that should be taken into consideration when choosing a digital camera.
Sony alpha 850 DxOMark review – August 27th, 2009