Noise, resolution and sensitivity
The 24.3-million-pixel sensor in the NEX-7 is the same as that used in the Alpha 77 SLT (single lens translucent) model.
The main difference between the cameras is that the Alpha 77 directs 30% of its light away from the sensor to the phase-detection system. With more light on the sensor, the mirror-free NEX-7 should perform better in low light.
At ISO 100, the NEX-7 hits an impressive 32 on our resolution chart with both JPEG and raw files – matching that of the Alpha 77.
By ISO 3200, resolution starts to fall, but only to a respectable 26 (the Alpha 77 resolved to 24). At ISO 12,800, the NEX-7 stays slightly ahead, remaining at 24 for the raw and JPEG compared to 22 and 18 respectively for the Alpha 77.
Noise is very well controlled in the JPEG files, remaining completely free of colour noise even at the highest ISO 16,000 setting and repressing luminance noise effectively even at ISO 6400, although detail suffers because of it.
Even in raw files, with noise reduction turned off, noise only starts to become destructive above ISO 3200 and colour noise is only present in the top two settings.
For most scenes it is quite safe shooting at ISO 100-1600, although the lowest setting should still be chosen for optimum performance.
Sony NEX-7 Resolution
Resolution & Noise: These images show 72ppi (100% on a computer screen) sections of images of a resolution chart, captured using the standard 18-55mm f/3.5-5.6 kit lens at 38mm f/8 setting. 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 is at the specified sensitivity.