[Paid Software Announcement and Discussion] GerritMaarten:
Some investigation on step sizes

Thx for ur explanation on the way your app handles the focusing. The problems are clear.

For your information:

The following data for the Canon 6D - 100mm macro L IS USM combination were found.

Ratios small medium and large step (from measuring focus points on a ruler):

> : >> : >>> = 56 : 7 : 1

Stepping from 0.30m to infinity needs:

> 4358 steps

>> 373 steps

>>> 66 steps

Below normalized ratio's for the different step sizes:

56 : 4.8 : 0.85

82 : 7 : 1.2

66 : 5.7 : 1

From the previous measurements I noted that 1 >> step just covered the DOF with aperture set at f=2.8.

Remembering the engraved apertures showing the DOF regions on manual focus lenses, the idea arose ratio step size wouldn't change much as function of the object distance.

For different distances the >> step size DOF ratio ranges (at f=2.8) from 1.1 at .3m, 1.2 at .5m to 1.4 at 2m. This means >> step size doesn't change much in relation to object distance. The >> step size is slightly smaller than the DOF at all distances. That is required for producing an all focused stack from individual pictures.

From the above one must conclude that for stacking purposes pictures taken at 1 >> step from each other can be stacked without blurring. And that is true at every distance of the object. That assumption proved to be workable.

The step size for different f values is D=integer(f/2.8) >> steps

The minimum number of pictures (n) needed from A to B (or from B to A which makes no difference for stacking purposes) if those points have a distance of P >> steps, is n=1+integer(P/D).

To get this working for any lens camera combination, one must determine at the lowest f value the step size that is just a bit smaller than the DOF.

Here is a way:

Place a centimeter ruler in front of your camera lens combination. Make sure it is in focus using the 10x magnification tool to determine the DOF in mm. Set A. Use > to set B at DOF distance from A. In focus bracketing you find the number of shots(= number of > steps).

Repeat this with >> and >>>. The lowest number of steps (greater or equal to 1) that just cover the DOF with the accompanying step size are the parameters that should be used for that camera – lens combination.

So maybe in a file of the camera-lens combinations that value could be written and used if so required in focus bracketing (for example: Canon 6D – 100mm L IS USM – 1 >>)

Remarks:

In the Canon 6D video doesn't simultaneous work with the use of WiFi.

After having shot a series of focus bracketing, it seems u have used up your A or B parameter so it cannot be used for shooting the same thing again. Could you copy the A and B for your internal calculations so the originals remain where they are and can be used again? If the points A and B were set using for example >> it would be nice those >> reappear with the previous set points A and B in the focusing screen.

Btw sometimes the focus points A and B unset appear as lower case(initially), sometimes as capitals (after returning from focus bracketing).

If possible it would be nice that after having done an auto-focus, in the background that sets point A, and that one after having done that one can go to the manual focus screen. (that is now blocked)

Unsetting A or B is only necessary after moving the lens away from B or A respectively, then check the step size and add that to your internal counter or if done so manually by pressing the button or by AF.