At effective aperture f/5.6, an aberration-free lens would be way out-resolving the sensor. So this situation is exactly what I described, "the Airy disk is small compared to the classic circle of confusion and/or sensor resolution
By the way the column in Rik's last-posted tables marked "Step Size" should be "DOF" I think, looking at the numbers.
The questions I get all refer to step size. It's a matter of taste whether the step size is equal to the 1/4-lambda DOF, versus somewhat larger or smaller. I've used "equal" because that seems to be a reasonable compromise. Chris S. would run smaller, seta666 would run larger.
The f numbers in the chart all seem a good stop too big.
The f numbers in the chart correspond to effective f/10.7 on a 15 megapixel APS-C sensor and f/14.2 on a 23 megapixel full-frame sensor. Those correspond pretty closely to "Diffraction Limits Standard Grayscale Resolution" at CambridgeInColour's diffraction calculator
. A user who wants sharper images at the cost of shooting more frames will prefer wider apertures, corresponding to fewer pixels across the circle of confusion.
One thing I hadn't realised is that if using microscope objectives, (ie about 2x NA 0.1, up) then all that determines the DOF is the NA. Forget the magnification. The Wave calculation rules so a 10x 0.45 gives the same dof as a 50x 0.45. (Need to check that!)
The wave calculation rules only if the captured images are diffraction-limited. 10X NA 0.45 is effective f/11. CambridgeInColour shows that an image at f/11 is affected by diffraction on a 15-18 megapixel APS-C sensor, but we know from the demo HERE
that f/11 is also sensor-limited by almost a full stop. In contrast, 50X NA 0.45 is effective f/56, which is strongly diffraction limited by everybody's evaluation. The 1/4-lambda DOF will be the same for 10X NA 0.45 and 50X NA 0.45, but it will be a lot harder to tell that with the 10X setup, using current sensors.