We shoot a specially designed chart in carefully controlled conditions and the resulting images are analysed using DXO Analyzer software to generate the data to produce the graphs below.
A high signal to noise ratio (SNR) indicates a cleaner and better quality image.
JPEG Signal to noise ratio
JPEG images from the Sony Alpha 77 show signal to noise ratio results that are on par with the Canon EOS 7D and Pentax K-5. These results show that noise is well controlled up to a sensitivity of ISO 3200, above this sensitivity value noise starts to become more apparent, but images still have lots of detail.
Raw signal to noise ratio
Raw images (after conversion to TIFF) from the Sony Alpha 77 have a better signal to noise ratio than the Canon EOS 7D and Nikon D300s. Although the Pentax K-5 has a slightly better score, the difference is marginal.
JPEG dynamic range
This chart shows that the Sony Alpha 77's JPEGs capture a wide tonal range up to a sensitivity of ISO 3200, at ISO 6400 the amount of tonal detail captured in the shadows and highlights deteriorates. This graph shows that from a sensitivity of ISO 100 to 1600 the Sony Alpha 77 JPEGS capture a greater tonal range than the Canon EOS 7D and the Nikon D300s, which is impressive given its higher pixel count.
Raw dynamic range
This chart shows that the Sony Alpha 77's raw images (after conversion to TIFF) capture a wide tonal range up to a sensitivity of ISO 6400, beating the Canon EOS 7D and Nikon D300s by as much as 2Ev. At the higher end of the sensitivity range the Pentax K-5 just has the edge.
For more more details on how to interpret our test data, check out our full explanation of our noise and dynamic range tests.