A sight aid including a supplementary sight alignment indicator having a projection plane and a projection device adapted to project a supplementary sight alignment indicator and at least one reference point on the projection plane, the supplementary sight alignment indicator is axially-centered with respect to the sight alignment indicator and spaced apart therefrom on the optical axis for forming a composite image with the image of the sight alignment indicator, the target image being viewable together by the user by means of the ocular lens and the projection plane is disposed at a distance from the sight alignment indicator. An adaptor secures the supplementary sight alignment indicator to a portion of the projectile device or the housing.