Pentax-DA* 200mm F2.8 Review

Bokeh

Bokeh derives from the Japanese word "boke", which means blur. In a photography context, bokeh refers to the qualities of the out of focus areas of an image. These qualities are dependent on various aspects of the lens' design, such as shape and number of aperture blades, spherical aberration correction, etc.

In order to evaluate the bokeh of the Pentax SMC DA* 200mm f/2.8 ED [IF] SDM, we took images of a test scene at various apertures. The test scene was made so it contained mainly background elements with textures, some foreground element, and specular highlights (which are necessary to observe the effect of the aperture blades on the image). Bokeh samples:

f/2.8		f/4.0
f/5.6		f/8.0
f/11		f/16
f/22

Verdict

As can be observed in the above images, the bokeh of the Pentax SMC DA* 200mm f/2.8 ED [IF] SDM is fairly smooth and there are no signs of harsh contrast or color transitions. The rendition of the highlights is fairly pleasant as well, no obvious texture can be seen. Because of the relatively shallow depth of field of this lens, the effect of the 9 straight aperture blades can be easily observed when stopping down. 

We can observe that the quality of the bokeh is maintained all across the frame, which would indicate that this lens is very well corrected for most optical aberrations. In this regard, the bokeh of this lens is fairly neutral (which is very typical of modern lens designs) since it does not introduce foreign shapes or textures in the out of focus areas (such as "swirls"). It is also worth mentioning the very symmetrical bokeh highlights (or "bokeh balls"), which generally is a very desirable trait.

In conclusion, we are very pleased with the bokeh of the Pentax SMC DA* 200mm f/2.8 ED [IF] SDM and we consider that this is one of many strengths of this lens, though it would certainly be interesting to see a version of this lens with rounded aperture blades.