An electronic device comprising a lens and a selector ring is disclosed. The selector ring is mounted for rotation about the lens and comprises a plurality of tabs projecting inwards towards the lens which engaging with and are held within a tab receiving groove comprising a plurality of spaced notches. Each of the notches is dimensioned to receive one of said tabs. A wave spring positioned between an annular ledge of the lens and the selector ring which biases the plurality of tabs against the groove and such that when each of the plurality of tabs is positioned adjacent a respective one of the notches, the tabs are biased into the notches thereby preventing said selector ring from being rotated. A user disengages the tabs from the notches by pressing said selector ring against the bias of the wave spring, thereby allowing the selector ring to be rotated.