My quick study of this matter a few years ago had
Originally Posted by ic-racer
me turn my attention to the purchase of an OM-10.
A more thorough study this pass confirms the
equation you use to be THE one to use. Print
size divided by negative size is specified
to be the method for deriving M&m.
Although a + 1 in each term appears to compensate
for aperture changes and the equation is described
as being accurate, I've not encountered any claims
of it being exact. So I wonder if the equation is
the last word?
Without the + 1s results will equal those of the
equation Nt = Ot x Ne^2/Oe^2; where the terms
are Old, New, time, and edge.
For more information on this subject and derivation
of other exposure related variables search Google
for, exposure enlargement calculations . Dan