Top: analytically derived radial profiles of normal optical depths on the (dashed lines) apastron and the (solid lines) periastron sides as a function of distance. Grains are assumed to originate from belts with r₀ = a_b = 100 au and eccentricities e_b of (red) 0.0, (blue) 0.2, and (black) 0.4. The ratio of drag and collision timescales is set to η = 100. At the belt edges, i.e. at the right ends of the curves, optical depth starts at finite values. Bottom: the ratios of optical depths on opposing sides for the same set of parameters. The dashed lines show the contribution from drag alone.