Sigma DP2 Quattro: lens sharpness
The Sigma DP2 Quattro would have benefited from a faster lens, especially for focussing in low light. f/2.8 is what you’d expect for a fixed zoom lens and not for a fixed 30mm prime, but the good news is that it’s very sharp in the center at this aperture, and the corners are not bad at all.
At f/2.8, the center image is already very sharp. There is some slight vignetting visible, and a small degree of curvature in straight lines. Corners are already decently sharp.
f/3.2 seems to be somewhat of a sweet spot, as both center and edges are sharp and there is vignetting has virtually disappeared.
Similar performance up to f/9 with some slight variation at different apertures in vignetting, but both center and edges remain very sharp.
Around f/11, diffraction starts dulling the image, with a loss of that signature Sigma sharpness pop. Both center and corners have equal performance though.
performance is similar up to f/16, the smallest aperture.
There is no camera that works in every situation. If you’re looking for a camera with a fixed lens that will work more-or less OK in every situation, don’t go for this one.
The Sigma DP2 Quattro will provide you with fantastic images in decent light if you stay below ISO 800 and f/11.