How exactly do you decide where to focus and what f-stop to use, especially when you want lots of DOF, for example for a landscape?
I'm interested in what people actually do in the field, rather than underlying theory or a link to an article showing someone else's technique.
Assume shutter speed and ISO are not concerns (e.g., on a tripod with a stationary subject). Assume we all know the basics of DOF. Don't forget diffraction.
1) Guess, shoot, chimp with magnification, adjust, repeat. A 3" LCD isn't the best viewer, but it's what you have.
2) Use rules of thumb, such as focus 1/2 or 1/3 of the way into the scene and use something around f/11 or f/16 for deep DOF. This could be the main method or a first step in method (1).
3) Use a DOF calculator (readily available on most smartphones). Limitations include estimating distance (just what is 60m away) and determining an appropriate circle of confusion (calculator defaults may not be appropriate for your purposes)
4) Use Merklinger's method: focus at infinity (or the furthest thing you want to be sharp), decide the size of the smallest near object you want to be identifiable, divide focal length by that size (in mm), result is f-stop. For example, if you are shooting at 22 mm and want a 2mm near object to be identifiable, shoot at f/11