Hi Russel
I can't remember actually using a Tukon tester before, so bear that in mind
I think the objective lens factor (correction for eye piece Filar measurement) is not the same as the objective lens magnification ie x10, X20, X50. Usually, (could be wrong with your model) the standard measuring objective lens will be X50 giving you an image magnification of ~X500 with a x10 eye piece or X625 with a x12.5 eye piece (x100, x200, x500 or x125, x250, x625 magnification sets). Using X50 objective I would expect the Filar units to be directly in micrometres ie correction factor x1. The X10 objective would have correction factor x5 and x20 objective x2.5.
It would be wise to check/calibrate the optical measuring system using a accurate stage micrometer or with micro samples of known dimension. That way you know for sure how to convert your Filar units. Then do some hardness checks using a calibrated hardness test block.