Sigma 30mm f/2.8 EX DN

Sigma 30mm f/2.8 EX DN Performance

At maximum aperture, sharpness is already outstanding in the centre of the image, and very good towards the edges. Stopping down the lens improves sharpness across the frame as far as f/5.6, where the clarity is outstanding across the frame.

Sigma 30mm DN MTF

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 kept low at all aperture, peaking at just over 0.75 pixel widths at f/16 and f/22. This low level should pose few issues, even with large prints and harsh crops from near the edges of the frame.

Sigma 30mm DN CA

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 well controlled. At f/2.8 the corners are only 0.9 stops darker than the image centre and visually uniform illumination is achieved by f/5.6. Mild barrel distortion of 0.821% is present, which shouldn't pose issues in normal shooting. If absolutely straight lines are required, the distortion is quite simple to correct as it is uniform across the frame.

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