Sigma 19mm f/2.8 EX DN m43

Sigma 19mm f/2.8 EX DN Performance

Sharpness in the centre of the image area is already outstanding at maximum aperture and the clarity towards the edges is very good. Stopping down the lens improves sharpness towards the edges further, with peak quality across the frame being achieved between f/5.6 and f/8.

MTF Chart

How to read our charts The blue column represents readings from the centre of the picture frame at the various apertures and the green is from the edges. Averaging them out gives the red weighted column. The scale on the left side is an indication of actual image resolution. The taller the column, the better the lens performance. Simple. For this review, the lens was tested on a Panasonic Lumix GF3 using Imatest.

Chromatic aberrations are reasonably well controlled, just exceeding 0.75 pixel widths towards the edges of the frame at f/5.6. This low level of CA should pose few issues, even in large prints, or harsh crops from near thee edges of the frame.

CA Chart

How to read our charts Chromatic aberration is the lens' inability to focus on the sensor or film all colours of visible light at the same point. Severe chromatic aberration gives a noticeable fringing or a halo effect around sharp edges within the picture. It can be cured in software. Apochromatic lenses have special lens elements (aspheric, extra-low dispersion etc) to minimize the problem, hence they usually cost more. For this review, the lens was tested on a Panasonic Lumix GF3 using Imatest.

Falloff of illumination towards the corners of the frame is reasonably well controlled for a wide aperture lens. At f/2.8 the corners are 1.08 stops darker than the image centre and visually uniform illumination is achieved by f/5.6.

Imatest detected 1.1% barrel distortion, which is a relatively high amount for a fixed focal length lens, although this should still be a low enough level of distortion to pose issues day to day. The distortion is uniform across the frame, so it should be quite straightforward to correct in image editing software if absolutely straight lines are required.

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