Irix 11mm F4 Firefly & Blackstone
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 are generally not sought after for their bokeh, since the short focal length yields a large depth of field. Nonetheless, in the right circumstances subject isolation is possible. At F4 and 11mm, our test subject isn't likely to be particularly impressive.
Bokeh Test
In order to evaluate the characteristics of the background blur, we took pictures at varying apertures, using these test parameters:
|
|
Results are directly transferable to APS-C cameras.
| F4 |  |
| F5.6 |  |
| F8 |  |
| F11 |  |
| F16 |  |
| F22 |  |
Our observations made with the Irix 15mm almost completely correspond to what we observe with the 11mm. The nine, round aperture blades produce mostly circular highlights, only deformed by the lens' distortion. The blur is more than adequate (notice the texture of the building on the lens) especially at larger apertures.
Considering the extreme nature of the lens' focal length, these results are above expectations.
More examples can be found in our Samples Gallery.
Verdict
The Irix 11mm's out-of-focus rendering exceeds our expectations. Considering the 11mm focal length, the bokeh, transitions and highlight definitions are simply better than we had any right to wish for.
