Samsung 20mm f/2.8 NX iFunction Pancake

Samsung 20mm f/2.8 NX iFunction Pancake Performance

At maximum aperture, sharpness in the centre of the image area is already very good, although the clarity towards the edges of the frame lags behind somewhat, just reaching fair levels of sharpness.

Stopping the lens down improves sharpness across the frame until f/4 and the clarity towards the edges of the frame continues to improve until the lens is stopped down to f/8. Resolution towards the edges is good between f/4 and f/8.

Resolution at 20mm

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 Samsung NX11 using Imatest.

Chromatic aberrations are relatively high for a lens of this type. Fringing exceeds one pixel width in area at apertures of f/8 and below, which may become visible in high contrast areas towards the edges of the frame.

Chromatic aberration at 20mm

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 Samsung NX11 using Imatest.

Falloff of illumination towards the corners of the frame is well controlled for a lens with an f/2.8 maximum aperture. The corners are only 0.768 stops darker than the image centre at f/2.8 and visually uniform illumination is achieved at apertures of f/4 or beyond.

Distortion is also very well controlled, with only 0.231% pincushion distortion detected by Imatest. This mild distortion shouldn't pose too many issues for general photography. If absolutely straight lines are paramount, you'll be glad to discover that the distortion pattern is uniform across the frame, which should make corrections easy to apply in image editing software afterwards.

Flare isn't an issue with this lens and contrast levels hold up well when shooting into the light.

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