An add-on device for an image scanner for scanning barcodes, the image scanner having a standard range lens, the standard range lens having a lens front and an optical axis; the add-on device comprising: a housing, the housing mounted to the standard range lens front on the image scanner; a lens holder with a first position for holding a first lens, a second position being an aperture, and a third position for holding a second lens; a high-density lens mounted in the first positon; an extended range lens mounted in the third position; the lens holder being mounted in the housing and being transverse to the optical axis of the image scanner; the lens holder being movable within the housing to alternately position the high-density lens, the aperture, and the extended range lens to be in alignment with the optical axis of the standard range lens of the image scanner; and characterized in that the image scanner is provided with a laser aimer and an illuminator; the laser aimer, the illuminator and the standard range lens being in a first linear relationship; the add-on device further comprising an aimer lens; the lens holder being provided with an aimer lens holder; the aimer lens being disposed in the aimer lens holder; the aimer lens holder being in a second linear relationship with the third position; the first position, the second position and the third position being in a third linear relationship; the second linear relationship being perpendicular to the third linear relationship; the second linear relationship corresponding to the first linear relationship, such that when the third position is in alignment with the optical axis of the image scanner, the aimer lens is in alignment with the laser aimer. a housing, the housing mounted to the standard range lens front on the image scanner; a lens holder with a first position for holding a first lens, a second position being an aperture, and a third position for holding a second lens; a high-density lens mounted in the first positon; an extended range lens mounted in the third position; the lens holder being mounted in the housing and being transverse to the optical axis of the image scanner; the lens holder being movable within the housing to alternately position the high-density lens, the aperture, and the extended range lens to be in alignment with the optical axis of the standard range lens of the image scanner; and characterized in that the image scanner is provided with a laser aimer and an illuminator; the laser aimer, the illuminator and the standard range lens being in a first linear relationship; the add-on device further comprising an aimer lens; the lens holder being provided with an aimer lens holder; the aimer lens being disposed in the aimer lens holder; the aimer lens holder being in a second linear relationship with the third position; the first position, the second position and the third position being in a third linear relationship; the second linear relationship being perpendicular to the third linear relationship; the second linear relationship corresponding to the first linear relationship, such that when the third position is in alignment with the optical axis of the image scanner, the aimer lens is in alignment with the laser aimer.