Noise, sensitivity and resolution
The Sony Alpha 57 has a sensitivity range of 71⁄3 EV at ISO 100-16,000, which can be extended to ISO 25,600 in the multi-frame noise-reduction setting.
With virtually the same sensor as cameras such as the Alpha 55, Nikon D7000 and Pentax K-5, it comes as no surprise that the Alpha 57 is capable of resolving a high level of detail. At ISO 100, the camera reaches the 26 marker on our resolution charts in raw and JPEG format.
Levels of luminance noise are inevitably higher than equivalent DSLRs at higher ISO ratings, due to the use of a fixed translucent mirror. However, luminance noise is only really noticeable at ISO 1600, and images are usable at this setting.
Higher levels of noise affect the resolved detail at higher ISO ratings, and for both raw and JPEG files the camera reaches the 24 marker at ISO 3200 and only 20 at ISO 12,800.
These images show 72ppi (100% on a computer screen) sections of images of a resolution chart, captured using the Sigma 105mm f/2.8 macro lens. We show the section of the resolution chart where the camera starts to fail to reproduce the lines separately. The higher the number visible in these images, the better the camera’s detail resolution at the specified sensitivity setting.
