The ε ring is the brightest and densest part of the Uranian ring system, and is responsible for about two-thirds of the light reflected by the rings. While it is the most eccentric of the Uranian rings, it has negligible orbital inclination. The ring's eccentricity causes its brightness to vary over the course of its orbit. The radially integrated brightness of the ε ring is highest near apoapsis and lowest near periapsis. The maximum/minimum brightness ratio is about 2.5–3.0. These variations are connected with the variations of the ring width, which is 19.7 km at the periapsis and 96.4 km at the apoapsis. As the ring becomes wider, the amount of shadowing between particles decreases and more of them come into view, leading to higher integrated brightness. The width variations were measured directly from "Voyager 2" images, as the ε ring was one of only two rings resolved by Voyager's cameras. Such behavior indicates that the ring is not optically thin. Indeed, occultation observations conducted from the ground and the spacecraft showed that its normal optical depth varies between 0.5 and 2.5, being highest near the periapsis. The equivalent depth of the ε ring is around 47 km and is invariant around the orbit.