I'm starting a project to calculate my own DOF tables. And of course, it all comes down to one's choice for the circle of confusion, "c".

What's a typical choice for "c"? I'm getting my formulae from an article that's decades old (not sure of the source), and they recommend using c=0.033mm. Does this value sound about right? (Not sure.) I would probably select a single value of "c" for the negative. If I decide to take into account enlargement factors for different formats, I can use multiples of this value.

I plan to calculate separate tables for each lens, and for each f-stop. Each table would include the near and far distances of acceptable sharpness, and the hyperfocal length.