Originally posted by reh321 . . . total message of "f/8 and be there" is to have your gear set up so the mechanics of taking a picture will require zero attention from you . . .
. . . unless or until you have time to refine that solution with better tools and technique. That goes without saying, doesn't it?
Let's not loose sight of @Panonski's original request for advice on determining and optimizing the window of satisfactory sharpness. No matter what your tools or technique, the answer lies in understanding the
principles of DOF/HDF and applying that information in a practical manner.
Sure, AE, AF and auto-ISO options are extremely useful tools -- in many cases they're the
best tools available today -- but they're not the ONLY tools. The basic principles of optics and photography haven't changed and thoughtful anticipation is always the first step toward success in
any task.
Pre-setting a logical combination of exposure and focus using the best available tools is a
practical philosophy of preparedness; not a final solution for either function. Just as was choosing to load a certain type of film to suit the expected conditions in the days before on-the-fly ISO and WB selection. (Thanks, digital gear. Swappin' out a film cassette in the field was a real PITA !
)
As for the potential accuracy of lens range scales, I don't recall EVER using the scale itself to set focus. Much easier and more intuitive to simply set manual focus on an anticipated point of interest through the VF and optimize DOF constrained by the allowable aperture determined by lighting conditions and desired shutter speed.
Even locking AF on a pre-planned point (maybe even an HFD point?) may have advantages in preventing focus hunting in some conditions -- especially with macro lenses.
Then there's also a certain degree of finesse in using CIF if you have pre-planned the target and desired DOF window/bokeh results. It certainly has helped if I have ready reference to a DOF chart
calibrated by my own prior personal experience with the gear in hand. That's chimping the old fashioned way -- before the shot!