The problem that I have discovered for myself is that the meters as they are manufactured do not see in the same way that panchromatic film does. In fact they will tend to give evergreen (pine) tree foliage too little exposure. The reason is that the evergreen foliage radiates a great deal of IR radiation. The meter sees it but the film does not. At the other end of the extreme these same meters will tend to give red too great exposure. Which is all good once we determine that is what is happening. For instance if one were to place the aforementioned green foliage at a zone III placement with even a brand new meter the negative and consequently the print will be more akin to a I 2/3 placement. The modification that Zone VI did to the Pentax meters went a long way to solving this problem through the use of sharp cutting filters as well as UV and IR filters and baffling. I have used several meters over the years and have found nothing aside from the modified meters that sees light in the same way as the film does. For that reason if one were to meter through filters with a unmodified meter the result would probably not be as accurate as one would hope. This has all been verified in my experience.