Which Gossen do you compare it to?

Hi Chan:

Comparison to a Gossen Lunasix 3 and Luna-Pro F. They agree with each other at the EV 14 setting. This is just a "static" comparison of what exposure is displayed at a EV 14 level on either meter, if that makes sense.

From your other comments it sounds like the Pentax output may not be a direct EV comparison, thus the difference.