The formula for calculating the maximum depth is universal for all resistivity meters. The exploration depth depends on the survey line length. the survey depth is usually 20-25% of the survey line total length.
For example, for 10m takeout cables, the total length of the cable is 10m*63=630m and this means the exploration depth is 0.2*630m to 0.25*630m.
The resolution is 10% of the exploration depth or half of the takeout spacing, the best resolution will decrease as the exploration depth becomes deeper.