Pentax-D FA 100mm F2.8 Macro WR

Bokeh

One of the most desirable attribute of a macro lens is a smooth, uniform background blur. That "blur" is referred to as "bokeh" in photographic circles. Some lenses (such as the DA 21mm Limited) produce a bokeh that can only be called "busy", with lots of textures and somewhat sharply defined edges. Macro lenses, on the other hand, are expected to deliver a featureless, even bokeh. You'll hear about "creamy" and "buttery" bokeh. Dairy products aside, it would be a poor macro lens that would let the background take precedence over the subject.

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: 100mm
  • Camera Mode: Aperture Priority
  • Shutter Speed: Determined by camera
  • ISO: 100
  • Distance to subject : 70 cm

The scene provides interesting features, both in and out of focus. The focus point selected is the horizontal light bulb in the first quarter on the left side of the image. Focus was obtained using live view and locked into place. Click on the images to see larger versions.

f2.8 f2.8
f4 f4
f5.6 f5.6
f8 f8
f11 f11

Other examples of the lens's performance regarding bokeh can be found in the Sample gallery. Here is one demonstrating the smooth transition from in-focus to out of focus.

Bokeh

Verdict

The 100mm macro WR is a macro lens with curved aperture blades. It would be alarming if the bokeh was anything less than superb. Luckily, this is not the case. The bokeh is smooth, even and pleasing at all apertures. It is, in short, just what anyone is entitled to expect from a lens such as this one.

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


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