A charging apparatus having a charging device for contact charging a rotatable member. Under the optimizing method, an optimizing function which takes at least one birefringence-related image aberration into account is minimized. The main tank supplies the recording liquid. In the thickness direction of the active material layer, porosity Pc of the current collector side lower half of the active material layer and porosity Ps of the surface side upper half of the active material layer satisfy Pc<Ps. The fluid inlet may further include an enclosure defining a vertically descending channel from the nozzle toward a bottom of a tub of the dishwasher and one or more dampers within the enclosure such that the water exiting the nozzle cascades down onto and over the dampers and out of the enclosures through one or more outlets of the enclosure to the bottom of the tub. Mz nMzn where M is Al, Si, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ge, Zr, Nb, Mo, Sn, Sb, Ta, W, Pb or Ce; z is the atomic valence of M; R1 and R3 are each an alkyl group of 1-5 carbon atoms, an acyl group of 1-6 carbon atoms or an aryl group of 1-9 carbon atoms; R2 is a monovalent organic group of 1-8 carbon atoms; n is an integer of from 1 to ; and R1, R2 and R3 may be the same or different.