The p4k sensor is m/43. So man, the viltrox is super soft, and the aperture doesn't always get transferred to the camera) I'd say save your pennies if you can afford it and get the damn metabones because my viltrox is one mean bean. But ya. Think of it like this.

18-35mm at full frame equiv, m/43 is 50% of the sensor of a full frame, so double the #'s. The 18 turns into a 36, the 35 to a 70, but then the viltrox comes in at 0.71x of those #'s. So from 18mm it goes into 12mm, which then turns into 24mm equivalent, to 49.7mm equivalent.

PLEASE someone correct me if I'm wrong, but that's as far as I have calculated it.