HD Pentax-D FA 24-70mm F2.8 ED SDM WR

Bokeh

Bokeh is a Japanese term which refers to the quality, look and texture of the background blur. It does not relate to the depth of field but to the areas in the image that are beyond the range that is expected to be in focus.

A smoother bokeh is generally perceived as being of a higher quality. Bokeh is influenced by the lens design, with a significant role being played by the aperture blades. Their number and shape will influence the look of the bokeh, especially around highlights and light sources.

The Pentax 24-70mm features 9 curved aperture blades, which should offer superb results regarding bokeh.

Bokeh Test

In order to evaluate the characteristics of the background blur, we took pictures at varying apertures, using these test parameters:

  • Tripod
  • 2s Timer
  • Focal Length: 70mm
  • Camera: K-1
  • Camera Mode: Aperture priority
  • Shutter Speed: Set relative to aperture
  • ISO: 100
  • Distance to subject: 2 meters

Results are directly transferable to APS-C cameras.

Pentax at 70mm
F2.8 Pentax F2.8
F4 Pentax F4
F5.6 Pentax F5.6
F8 Pentax F8
F11 Pentax F11
F16 Pentax F16
F22 Pentax F22

Our test lens produces a beautiful rendering of the out of focus areas. Highlights in particular are pleasing, with a beautiful circular shape created by the nine rounded aperture blades. Some people have reported of ring patterns in those highlights; this is not something that we observed during our tests. There is also no deformation of the highlights in the corners, the shape remains circular.

In general, the bokeh is smooth, especially at wide apertures. Without reaching the levels of quality of a dedicated macro lens, there are no harsh transitions or overly defined borders. These results are above expectations for a zoom lens.

Verdict

The bokeh produced by this lens is pleasingly smooth. Its main quality is that it is unobtrusive, with beautifully shaped highlights and gradual transitions.

Further examples of the performance of this Pentax lens can be found in the sample gallery near the end of this review.


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