Some enlarging meters are also very good B&W densitometers:

http://www.darkroomautomation.com/em.htm

If you are enlarging the negatives then the proper place to
read the density is at the enlarger's easel. It gives you
the effective density in your equipment - taking into account
flare and calier effects.

If you are doing zone system calibration then what you want
is the EI and development time that gives perfect prints on
#2 paper in your enlarger, not some arbitrary set of densities.

You also need to find the total exposure to the paper
that results in almost not white and almost but not quite
totally black. The difference in exposure in stops between
these points is equal to the difference in negative density
you want for spanning Zone I to Zone IX.

--
Nicholas O. Lindan
Cleveland Engineering Design, LLC
Cleveland, Ohio 44121