Resolution, dynamic range and noise
Sigma dp2 Quattro review – Resolution
The Quattro’s resolution is hugely impressive at low ISO settings, at around 3600lp/ph, which is about as high as it could possibly record given its pixel count.
In raw it gradually falls at higher ISO settings, to about 2400lp/ph at ISO 400. But in JPEGs, it literally halves at ISO 1600 to 1800lp/ph due a change in processing mode, then drops to about 1600lp/ph at ISO 6400.
Sigma dp2 Quattro review -Dynamic range
The pattern here confirms the Quattro as a low ISO camera. Dynamic range is very respectable at ISO100, at about 1.6EV, but it falls off very quickly from ISO 400 onwards. A value of 8.7 EV at ISO 800 isn’t great for an APS-C sensor, and dynamic range falls monotonously thereafter, indicating a lack of ability to record shadow detail.
Sigma dp2 Quattro review -Noise
At low ISO settings, the Quattro gives extremely clean images, but things start to go badly awry at ISO 1600 and above. JPEGs are practically unusable at ISO 3200 and 6400, and while raws aren’t so bad, they show exceptionally high luminance noise.
