HD Pentax-DA Fish-eye 10-17mm F3.5-4.5
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. Its shape will influence the look of the bokeh, especially around highlights and light sources.
Extreme wide lenses struggle to create noticeable bokeh thanks to their deep depth of field. The six straight aperture blades of the HD DA 10-17mm also won’t be particularly effective to create rounded highlights. Its close focusing capabilities will mitigate this to some extent.
Bokeh Test
In order to evaluate the characteristics of the background blur, we took pictures at varying apertures, using these test parameters:
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| F4 |  |
| F5.6 |  |
| F8 |  |
| F11 |  |
| F16 |  |
| F22 |  |
The HD DA 10-17mm Limited's out-of-focus rendering is a pleasant surprise. The lens manages to create nicely rounded highlights, and the background is devoid of harsh transitions. Even as the aperture closes down to F16 and F22, the highlights remain mostly circular and the texture is never busy. Beautiful results, certainly.
More examples can be found in our Samples Gallery.
Verdict
Despite being an ultra wide fisheye with only moderately fast apertures, the HD DA 10-17mm produces pleasing and smooth bokeh at all apertures. In particular, the highlights are mostly circular, without distracting edges or shapes.
