Micro 4/3 Lumix Focus Bracketing setting question

[Paul-H]

Hi all.

I have a question about the settings when using the focus bracket option on my Lumix G90.

I did ask this over on mu43 and didn't get the answer so it might be an unknown question so apologies for that, but here goes just in case.

There are two settings one for number of shots in the bracket sequence and that is an obvious one, but the other one is for the amount the focus steps between each shot, anyone know how to find out just how much the step is for each of the available settings, is it for example 1mm between shots at setting 1, 10mm at setting 2, 20mm at setting 3 etc, or something else.

Thanks for any help with this.

Paul

 

[archaeopteryx]

In all manufacturer's implementations I'm aware of the step size parameter controls frame to frame overlap as a percentage of depth of field. Step distances therefore vary with magnification (or, equivalently, focal length and focus distance) and aperture as well as the size parameter. The most detailed work up I've encountered is for Olympus, some of it in this DPR thread (see also the collection of links at its end).

At moderate magnifications it's probably easiest to focus bracket a ruler of suitable length for measuring step sizes (don't forget to correct for viewpoint geometry). For magnifications below that it's probably looking at the frames in the bracket and measuring camera to subject distances. At higher magnifications consider microscope stage calibration slides and similar.

Edit: Had a minute to look up and add the link.