Really nice job folks. It’s a tough subject, but defining the area of focus is part of composition.

I grew up with the Scheimpflug principle and view cameras, so today with these new fangled cameras I prefer a tripod, neutral density filters, manual focus and exposure (handheld meters) and the occasional use of PC lenses which give swing and tilt capabilities to DSLRs.

All that aside, there are a few tricks from the past that still hold to this day especially when there’s a desire to quickly establish what focus range is going to be produced. To keep the math out of the equation, I scan the areas of focus I want from front to back and note them on the lens barrel with my fingernails. Since the general rule of thumb for the focus range is 1/3 in front and 2/3s in back of the focus point, I use the depth of field scale on the lens to reproduce that range, setting the aperture appropriately. Then I look with the aperture stopped down before shooting. This isn’t for the macro examples in your post where the depth of field is measured in inches, but for scenes where you either want everything tack sharp, or a subject floating in a mist of diffusion.