Patrick asked: "Let's say I want to under/overexpose a shot by 1/3 of a stop on an MZ-S how do you you do it ?"
You can get precise exposure adjustments by adjusting the ISO speed. For example, to give it just a little more light, adjust the ISO to 90 for ISO 100 slide film. Setting it to ISO 110 would give you just a little less light. Tom Reese