Robert Meier wrote:
>
> --- Lars Michael <[EMAIL PROTECTED]> wrote:
> > Depth of field is a function of magnification ration
> > (subject to film/sensor) during exposure, and does
> > not
> > depend on the size of the print.
>
> Well, it DOES depend on the size of the print and the
> viewing distance. The reason why these two factors are
> usually not mentioned is because of the way DOF
> historically was defined. The DOF as we know it is
> based on the assumption of a certain print size and
> the corresponding viewing distance. If you do not
> comply with these assumptions you will have to take
> these factors into account as well.
>
> Robert
Exactly what I was driving at. The size of the allowable Circles of
Confusion for the limits of DOF are based on an expected viewing
distance, which is assumed to be a function of print size. Of course
these traditional values of CoC were also based on very old film with
pretty low resolution. Harold Merklinger has some interesting, and kind
of wierd, articles on DOF that treat this and other aspects of the
problem. Sorry, I don't have the URLs handy, but a search should turn
it up if anyone is interested.
Thanks Robert.
Mike
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