Shadow Noise

The Sony A77 uses a newly developed 24MP CMOS sensor. This follows on from the last-generation 16MP sensor which has impressed us greatly in the original SLT-A55, the Nikon D7000 and the recently-reviewed NEX-5N. As we can see from the example images below, all taken at base ISO, at a pixel level the A77 is a close match for the Nikon D7000 (and by extension all of the cameras which use the same sensor - the A55, Pentax K5 and Sony NEX-5N amongst others) but slightly superior to the older Canon EOS 7D. You can clearly see that shadow areas in our sample scene which are contain detail in the A77 are becoming 'blocked up' in the 7D, and detail in colored areas is visibly better defined.

This might seem like extreme pixel-peeping and of course in a way it is, but there are practical ramifications. It means that you can draw more detail from the shadow areas of the A77's raw files than you might expect from older DSLRs (like the A700), and with less of a penalty in noise (remember the images below were converted from raw files with Adobe Camera RAW NR turned off). Accordingly, you can use functions like Sony's Dynamic Rage Optimization (DRO) confident that you won't give shadow noise an unpleasant boost.

Compared to Canon EOS 7D (18MP) @ ISO 100

Sony SLT-A77 - ACR+3.0EV (ACR NR: 0) Canon EOS 7D - ACR+3.0EV (ACR NR: 0)
100% crop 100% crop
100% crop 100% crop

Compared to Nikon D7000 (16MP) @ ISO 100

Sony SLT-A77 - ACR+3.0EV (ACR NR: 0) Nikon D7000 - ACR+3.0EV (ACR NR: 0)
100% crop 100% crop
100% crop 100% crop