I use
a DoF calculator on my iPodTouch and old manual focus prime lenses.
This is one of the few instances where Peterson's going off experience in the film days with manual focus lenses, rather than dealing with the current lenses a new dSLR user faces. The 18-55 kit lenses, for example, have no distance scales at all.
For me, I think everywhere Peterson uses f/22 in
UE ought to be replaced with f/16, because of our ability to see the diffraction effect, now that we're working at higher resolutions than we did with film, but he's never gonna change that setting; he loves f/22.
The thing is, back in the (older) film days, we were working not only with manually focused lenses, but also all primes, and we were all using the same image size (35mm film). So the lenses could look like this:
On the bottom: the aperture setting ring.
On the top: the focus ring with the distance scale, marked off in both feet (yellow) and meters (white).
In the middle: the DoF scale.
To set this lens to hyperfocal distance (on a full-frame body), all I have to do is put the ∞ symbol on the distance scale opposite the aperture I'm using on the right hand side of the DoF scale. Then I'm set to hyperfocal, and where my aperture on the left is on the distance scale is my near focus distance. (Ain't sliderule technology grand?)
Of course, this doesn't work on a crop body camera (sigh). Hence my need for a DoF calculator/
chart in the field.
Remember that hyperfocal depends on three things: Your aperture, your sensor size, and your focal length. With a prime lens and film, two of those values are fixed, so you could have a DoF scale like that. With zooms, it's kind of impossible.
Distance scales are far less useful these days, because everything's optimized for autofocus, which means shorter distance "throws" (I.e., the full focus range on the lens above is about 270° or so (I.e., the ring twists 3/4 of the way around the barrel going from the smallest focus distance to infinity)--I can manually focus with great precision. On my 18-55, the full focus throw is maybe 30°. That's why modern distance scales on autofocus lenses are kinda/sorta useless--too tiny to mark off or use with any precision. But it helps make the autofocus faster and easier on the mechanics.