Lensbaby Burnside 35mm F2.8

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.

The Burnside is designed to offer a distinctive, unusual bokeh rendering. This evaluation with therefore be of paramount importance.

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: 35mm
  • Camera: K-1
  • Camera Mode: M mode
  • Shutter Speed: Set relative to aperture
  • ISO: 100
  • Distance to subject: 1.5 meters

Results are directly transferable to APS-C cameras.

The secondary aperture can be tuned continuously. However, the lens offers four soft clicks to mark extreme and intermediate positions. We will test these four settings separately.

Secondary iris open

F2.8
F4
F5.6
F8
F11
F16


Secondary iris closed by a third

F2.8
F4
F5.6
F8
F11
F16


Secondary iris closed by two thirds

F2.8
F4
F5.6
F8
F11
F16


Secondary iris fully closed

F2.8
F4
F5.6
F8
F11
F16


The Burnside 35mm's out-of-focus rendering is interesting, to say the least. The swirly effect which is the hallmark of this lens is evident at wider apertures, and it becomes more subdued at F8 and beyond. The strong field curvature is at least in part responsible for this swirl: as the secondary aperture closes (and perceived depth of field increases accordingly) the swirl becomes less prominent.

In other words, to maximize the swirly effect, one should in theory use a wide aperture and leave the secondary iris open. However, since closing the secondary iris makes objects near the edges slightly sharper, in many cases it might be better to close that iris partially, as can be seen in the images below, shot at F2.8.

Open
Closed by a third
Closed by two thirds
Closed

There is no single, ideal recipe. Users will get better results after some experimentation. And "better" might be too strong a word: there is no single best way to use the Burnside. It all depends on the desired rendering.

In summary, the swirly effect will be present in most cases, and can be reduced by closing down the main or secondary apertures. Closing the latter will also have the effect of increasing dramatically vignetting, which can also be used creatively.

Much more examples can be found in our Samples Gallery.

Verdict

The Burnside 35mm delivers pleasing bokeh with soft transitions and a smooth texture nearer to the center. Closer to the edges the Petzval design makes the bokeh more dynamic, with the unmistakable swirly effect. Even without curved aperture blades, the eight blades of the Burnside help deliver results that are certainly better than average, especially at wider apertures. The swirl creates a unique rendering which helps to isolate the subject in an unusual way.


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