Enlarging lens barrel

An enlarger lens barrel has a cavity provided with an outwardly directed window and a longitudinal bore defining a light passageway between the cavity and the enlarger light source. A diaphragm aperture adjusting ring is rotatable on the barrel and carries a transparent indicator ring provided with aperture designating characters which are movable with the indicator ring across the window. Housed in the cavity is a transparent light guide member having a cylindrically concave radially extending face confronting the bore and a transversely ribbed inside face including longitudinally and slightly radially spaced transverse faces reflecting light incident thereon from the passageway to the window to longitudinally spread the light incident thereon which is transversely diverged by the concave face. The rings are longitudinally shiftable between increment and continuous adjustment positions.