Mark Cassino <[EMAIL PROTECTED]> wrote: >If you don't mind showing me how aperture diameter (as opposed to f stop) >fits in, I'd like to see.
Well, aperture (physical size), f-stop and focal length are mathematically related: If you know any two you can calculate the third. The same is true of focal length, subject distance and magnification. I have seen a formula for calculating DOF based on f-stop, focal length and subject distance (this is the most convenient one to use in the field), but a little algebra should suffice to generate other formulae. You have to know the focal length (obviously!), desired COC and either f-stop or aperture AND either subject distance or magnification. There would seem to be four possibilities: Focal length, aperture, subject distance Focal length, aperture, magnification Focal length, f-stop, subject distance Focal length, f-stop, magnification Here's a page that shows the formula with focal length, f-stop and subject distance. Math buffs should be able to calculate the others! http://dfleming.ameranet.com/equations.html -- Mark Roberts Photography and writing www.robertstech.com
