As described on the previous page,
Bokeh is the term used to desribe the quality of the background blur in a photo.
This page is an attempt to show how background and foreground blur differ,
and how it affects the bokeh of a lens .. in this case the Nikon AF-D 80-200mm f2.8 -
used here at f4 with studio lighting. The camera body is a tripod-mounted Nikon D100.
A single photograph was been reduced in size to show the set-up, and the following detail
photos are unmanipulated and are actual size edits of the single original image -
so no artifacts were introduced by post-production.
foreground and background blur
In short - if the background blur is softer than the foreground blur, as in these photos, then the bokeh is good. If the background blur displayed by a lens has wiry edges to it, (similar to that seen here in the foreground photo), then the bokeh is regarded as poor.
The overall set-up with a figurine in the middle on which I focused. The toy tree and paper-clip to the left of the figurine is in the background and the toy tree and paperclip on the right is in the foreground. Both the foreground images are 10 cm in front of the figurine, and both the background images are 15 cm to the back of the figurine. (This photo has been reduced in size from the original image file.)
This is the background image. Notice how the blur of paperclip is much smoother than the blur in the next photo. The blurred tree also looks smoother than in the next photo. (This photo is a same-size edit from the original image file.)
This is the foreground image. Notice how the blur of paperclip is more 'wiry' and has sharper edges to it than the blur of the previous photo. The round shape of the tree doesn't seem to fade into a soft blur like in the photo above, but seems to have a more sudden edge to it. (This photo is a same-size edit from the original image file.)
In short, this lens shows soft creamy out-of-focus background areas - and this is good bokeh.
The foreground isn't normally considered in terms of bokeh.
However, if the background looked as 'wiry' and harsh as the foreground image here, then the bokeh would be considered poor.
Please feel free to e-mail me with comments & questions.
Neil van Niekerk