Here are the images I promised earlier. These were shot at rather high ISO, because I was in fading light on an overcast day. ISO was typically 3200. That would have no effect on the bokeh, of course. These were processed with DxO Photolab 2, but with nearly all corrections turned off. I left the tonality sliders to adjust the curves. No sharpening, no noise reduction, and no other adjustments that might introduce artifacts.
Japanese maple series:
Leaf with distant landscape as background, at f/4. The background is at least 30 feet away, and some of it farther:
Leaves with other leaves behind them. The leaf in focus is about a foot or two from the camera, the background leaves are 8-15 feet away, with overcast sky showing through. I made two of these. The first one shows the foreground leaf in focus, and the bokeh is neutral--the edges are neither faded nor brightened. That means the edge of the blurred spot is rather crisp, which can introduce false patterns as the spots overlap.
But when the foreground is out of focus, things get a big wild. Here, I adjust the focus to a point about halfway between the foreground leaf and the background leaves. The foreground leaves really went nuts with all sorts of diffraction artifacts.
Azalea series:
I set up the tripod and photographed an azalea leaf at three apertures. The leaf is focused at 1:1--minimum focus for the 120 Macro. The shutter speed ranged from 1/25 to 0.6 seconds. The background is quite nice on all of these.
F/4:
F/8:
F/11:
Birdhouse series:
As above, but focused to about two or three feet, with a background 70-400 feet distant. The shutter speed was 1/8 at the smallest aperture, and the birdhouse was swaying slightly, so there is a tiny bit of horizontal motion blur. The bokeh for these gets a bit clumpy, but not objectionably so.
F/4:
F/8:
F/11:
Chain series:
Here, the chain is about a foot from the camera, and the little cedar bush in the background is about 3 or 4 feet from the camera. Same three apertures. Here, the bokeh is a bit clumpy, but again not objectionably so.
F/4:
F/8:
F/11:
Bush and Dogwood series:
Two pairs of photos, here. For the first, the subject is at about 4 feet, background is at 20 feet. The branches in the background are rendered with neutral bokeh--neither bright nor faded edges. But those clean edges are still edges. Faded-edge bokeh would be much prettier here.
F/4:
F/11--I'll take neutral bokeh over insufficient selective focus to isolate the subject:
Here, the subject is at 2 feet and the background at 4 feet. Those edges really create some false patterns here:
F/4:
F/8--again, too little subject isolation. But the bokeh patterns are small enough not to add together in distracting ways:
Th 120 Macro performs like most highly corrected lenses. The out of focus spots expand into an even disk with no fading or brightness at the edges.
With a classic (read: old) Sonnar, the edges would be faded at wider apertures. With some really vintage lenses (Heliars, for example), the out of focus patterns would be distorted into tangential ovals, creating a swirly pattern.
But with many lenses, the out-of-focus highlights are bright. In this image, the highlights are bright-edged, but are tolerable because they are small. This photo was made with an otherwise superb 121mm f/8 Super Angulon on 6x12 Velvia, mounted on a Sinar view camera, shot at f/16:
(It's the same Japanese Maple, but in a much more colorful year. And then there's the Velvia effect.)
And from my article, here's a 180mm f/2.8 Carl Zeiss Jena Sonnar (aka, Wide Smooth Brush), at f/4, showing the effects of the faded edge at wide apertures:
Rick "we report; you decide" Denney