Pentax-D FA 100mm f/2.8 Macro WR Lens Review

Pentax-D FA Macro 100mm f/2.8 WR Performance

Sharpness is already excellent in the centre of the frame and good towards the edges of the image at f/2.8 and stopping down as far as f/5.6 improves performance further. Here sharpness is outstanding in the centre of the frame and excellent towards the edges.

MTF @ 100mm

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 extremely well controlled, barely exceeding 0.25 pixel widths. This low level of fringing will be difficult to spot, even in harsh crops, or large prints.

CA @ 100mm

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 also well controlled for a lens of this maximum aperture. At f/2.8 the corners of the frame are only 0.71 stops darker than the image centre and visually uniform illumination is achieved with the lens stopped down to f/5.6 or beyond.

Distortion is virtually negligible. Imatest was only able to detect 0.07% pincushion distortion, which is an extremely low level and should not require correction, even by the most discerning photographers.

During testing, this lens proved itself very resistant to flare and contrast levels are retained well, even when shooting into the light. The hood also does an excellent job of shading the lens from extraneous light that may cause issues.

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