Consolidating Sony’s entry-level SLT line-up, the Alpha 58 replaces both the Alpha 37 and Alpha 57. Phil Hall finds out how successful the merger has been. Read the Sony Alpha 58 review...
Sony Alpha 58 review – Noise, resolution and sensitivity
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.
The new 20.1-million-pixel sensor delivers very good levels of detail. It can resolve to around 28 lines per mm (lppm) at ISO 100, only tailing off to just over 22lpmm at its highest ISO of 16,000, which compares favourably to its rivals.
At its base ISO of 100, images from the camera are virtually noise-free, though subtle signs begin to appear at ISO 800. Above that, the gritty texture of noise appears in raw files at ISO 1600. This increases further as the sensitivity is increased, with luminance noise compromising fine detail and chroma noise deteriorating the image. This is to such an extent that I’d think twice about shooting at ISO 6400 and above, with the Alpha 58 displaying noticeably more image noise than its rivals at identical sensitivities.
The Alpha 58 tries to combat this when shooting JPEG files at these higher sensitivities, but the camera’s in-camera processing delivers mushy-looking files with considerable loss of detail.