Pentax HD FA* 70-200mm f/2.8 ED DC AW Review

Pentax HD PENTAX-D FA* 70-200mm f/2.8 ED DC AW Performance

At 70mm, sharpness levels are just a shade below excellent in the centre of the frame, with performance towards the edges reaching good levels. Stopping down to f/5.6 results in outstanding sharpness in the centre and excellent sharpness towards the edges of the frame at this focal length.

Zooming to 135mm, sharpness drops to very good levels in the centre of the frame, with performance towards the edges of the frame remaining good. Peak performance is achieved between f/5.6 and f/8 where sharpness is outstanding in the centre of the frame and excellent towards the edges.

Finally, at 200mm, the way this lens performs similarly to the way it does at 135mm, but at slightly reduced levels of sharpness overall. At maximum aperture sharpness is good in the centre, but only fairly good towards the edges of the frame. Sharpness is excellent in the centre between f/5.6 and f/8 and very good towards the edges of the frame between f/5.6 and f/11.

MTF@70mm
 

MTF@135mm
 

MTF@200mm
 

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-3 using Imatest.

Chromatic aberrations may become visible under certain circumstances, with fringing exceeding 1.25 pixel widths at 200mm and f/2.8. Although this is a still a reasonably low level of fringing, it may become visible along high contrast regions of images on close inspection. Chromatic aberrations are well controlled throughout much of the rest of the zoom range.

CA@70mm
 

CA@135mm
 

CA@200mm
 

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-3 using Imatest.

Falloff of illumination towards the corners of the frame is well controlled. At 70mm the corners are only half a stop darker than the centre of the frame and at 200mm the corners are only 0.9 stops darker. Visually uniform illumination is achieved with the aperture stopped down to f/5.6 or beyond throughout the zoom range.

Distortion is very well controlled at both ends of the zoom range. Imatest detected 0.9% barrel distortion at 70mm, which is replaced by 0.2% pincushion distortion at 200mm. The distortion pattern is uniform across the frame, which should make it relatively easy to apply corrections in image editing software afterwards if absolutely straight lines are necessary.

During testing, this lens proved itself very resistant to flare and contrast levels are good, even when shooting into the light, thanks to the combination of Pentax HD and the new Aero Bright optical coatings, which give reflections on optical surfaces a red hue, similar to what you may have seen on binoculars of a certain vintage. The petal-shaped hood does a good job of shading the lens from extraneous light that may cause issues.

Value For Money

Being priced at around £1850, this lens does cost more than equivalent optics available for Canon and Nikon camera systems, by around £300.

There is very little competition from third party manufacturers left as Sigma have discontinued their current Pentax mount version of their 70-200mm f/2.8.

Tamron's 70-200mm f/2.8 Di LD IF is currently pretty much the only equivalent lens available for Pentax at the moment. It may lack weather sealing, fancy optical coatings and even silent focusing, but it is substantially less expensive, being available for around £470.

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