Aperture: Wide Open or Closed?

[mrca]

Keen, certainly, if the background gives context and isn't cluttered or distracting, by all means include it with the subject. Contrast of sharpness between subject and bg with good bokeh makes the subject stand out.

 

[KmH]

Aperture: Wide Open or Closed?

Middle apertures - f/4 to f/11 - stopping down from f/1.8, f/2, or f/2.8.
Fast lenses that delivers their sharpest focus at their widest aperture are rare.

 

[petrochemist]

If circumstances permit I'll try to chose an aperture that gives the DOF required, but lighting, movement, lens & time to make adjustments all force compromises.

Several of my lenses have no aperture adjustment, currently they all just get used at whatever they give but I have plans to add control for a few of them such as my 40mm/2.8 shift lens, 85mm/2.8 and my 50mm/1.2. The mirror lenses & microscope objectives have less to gain from bolt on modifications.

In portraits I often want the background to be slightly softened but still quite recognizable, other times loosing the background completely is more important than keeping the ear lobes sharp.
Much the same can be said for wildlife, but with this there can be foreground elements to get rid of too.
For motorsports shutter speed is usually king, wanting as fast as possible for some shots & the maximum I can smoothly pan with for others. In many locations there is crash netting to be blurred out of shot too.
With macro & micro it's usually difficult to get enough DOF, on one occasion I found even with focus stacking I couldn't get the whole of my subject's foot joint sharp (is it an ankle still with a fly?). Smaller focusing movements than used to get 5 shots were unfortunately not practical with the hardware in use.

To date I've tried apertures from f/1.2 to f/128+. In time this range will no doubt be increased a little further, but still MOST of my shots are between f4 & f11.