5. When the image is out of focus

Bokeh relates to the fashion in which the out-of-focus areas of the image is rendered. The word itself is of Japanese origin, and the importance and even existence of 'good' bokeh have been a hotly debated topic for years. Suffice to say that some lenses have it, some not and some like it hot.

Amongst the Nikkors, the AFD 85 mm f/1.4 lens has long enjoyed a well-deserved reputation for its superb bokeh. Thus, in images taken with that lens, the sharply focused subject is set against a pleasingly silky smooth background. The transition from in-focus to out-of-focus occurs gradually. A good example of poor bokeh is the AFS 300 mm f/2.8 Nikkor, which despite its excellent sharpness tends towards producing hash backgrounds when it is stopped down. A large number of aperture blades gives a more circular opening when the lens is stopped down, but this in itself is not sufficient as witnessed by the 85 and 300 mm Nikkors both of which have a 9-bladed aperture.

It became quickly obvious the 70-200VR had a very pleasing image rendition, in fact, the images showed an attractive bokeh up with the very best of lenses. I did a test series in which the reigning bokeh champion, AFD 85 mm f/1.4 Nikkor, was pitched against the VR newcomer. To make realistic assumptions I shot only hand-held with or without VR activated (hence a slightly different composition of the test images), and delibrately shot branches set against a bright background. This is a very revealing subject for bokeh and most lenses will render out-of-focus lines in a harsh and unpleasant manner. Not so the VR lens, as depicted below. Clearly seen also is that VR mode does have a bearing on bokeh. The more active the VR, the less attractive the bokeh. And the king on the hill, AFD 85/1.4, still holds it top position against the new challenger. The difference isn't that great, however.

	AFD Nikkor 85 mm f/1.4 1/1500 sec, f/2.8 (Note the absolutely marvellous, creamy rendition of the out-of-focus background. The attractive bokeh is a hallmark of this superb portrait lens)
	AFS 70-200 mm f/2.8 G Nikkor VR @85 mm 1/1500 sec, f/2.8, VR off

	AFS 70-200 mm f/2.8 G Nikkor VR @85 mm 1/1500 sec, f/2.8, VR Normal
	AFS 70-200 mm f/2.8 G Nikkor VR @85 mm 1/1500 sec, f/2.8, VR Active

Because VR influences, and may degrade, bokeh, the photographer should have this fact in mind while shooting details are planned. If utmost image smoothness is required, you might consider switching VR off and work with a tripod-mounted lens instead.

Towards 200 mm the background blurring attained by the 70-200 VR was creamy and silky smooth, entirely up to the bokeh of the very best performers. VR mode once again did influence bokeh, but less obvious as with the shorter focal settings of the lens.

The Long March Towards Revolution: AFS 70-200 mm f/2.8 G ED IF VR Nikkor Reviewed