Pentax SMC P-D FA 50mm f/2.8 Macro Lens Review

Pentax SMC P-D FA 50mm f/2.8 Macro Performance

At maximum aperture, sharpness in the centre of the frame is already outstanding, and clarity towards the edges of the frame approaches excellent levels. Stopping down to f/8 results in outstanding sharpness across the frame.

CA@50mm

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 Pentax K-5 IIs using Imatest.

Chromatic aberrations are well controlled, with fringing remaining just exceeding half a pixel width at maximum aperture, towards the edges of the frame. This low level of fringing should barely be visible, even in large prints, or harsh crops from the edges of the frame.

CA@50mm

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 Pentax K-5 IIs using Imatest.

Falloff of illumination is well controlled for a lens with an f/2.8 maximum aperture. At f/2.8 the corners of the frame are 0.984 stops darker than the image centre and visually uniform illumination is achieved with the lens stopped down to f/5.6 or beyond.

A virtually indistinguishable amount of barrel distortion is present in images taken with this lens. Imatest detected 0.097% barrel distortion, which will be very hard to spot, even if straight lines very near the edges of the frame run absolutely parallel with the frame border.

During testing, this lens proved itself very resistant to flare and contrast levels remain good, even when shooting into the light. A deep circular lens hood comes supplied as standard, but as this lens controls flare so well, you probably won't need one, which is just as well, as the hood may get in the way when shooting at close distances.

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