Potential

To view potential lines, use a color scheme that varies rapidly. "Spectrum stripes" color scheme varies linearly and so, like contours, each color change represents a fixed change of potential. "Spectrum stripes log" varies logarithmically. This means that changes of color depend on the ratio of potential, not the absolute value. Therefore it is good for showing equipotentials, which vary slowly far from the boundary of the set and quickly closer to the boundary.

It is interesting to use a low magnification (say 0.1) and very low iterations: 2,4,8,16, etc. Then gradually increase magnification.