Adolf Luther, 'Zwei Brennpunkte', 1968, 2 layers of 16 square concave mirrors (in 2 sizes: 17 x 17 cm on 35 x 35 cm) mounted on a black wooden plate, with acrylic glass hood, 150 x 150 x 11 cm, Photo: setform.de, Adolf Luther, Kinetisches Spiegelrelief, 1974, 13 over 12 round concave mirrors over 16 square mirorrs (with rounded corners), mounted on a black wooden plate. With electric drive, transmission belt and acrylic glass hood, 104,5 x 104,5 x 17,5 cm, Photo: setform.de, Adolf Luther, Hohlspiegelobjekt (Concave mirror object), 1968, 6 x 6 cm concave mirrors on black wooden plate in aluminum frame, 71 x 71 x 11 cm, Photo: Archive, Adolf Luther, Hohspiegelobjekt, 1969, 3 x 3 semitransparent concave mirror lenses and flat mirror in acrylic glass box, 118,5 x 118,5 x 5 cm, , Adolf Luther, Sphärisches Hohlspiegelobjekt (beleuchtet), 1979, 8 x semitransparent mirrorstripes, 1 flat mirror, plexiglass, flourescent lamp, 40 x 40 x 16.5 cm , Signature: Luther 79, Stamp: Sehen ist schön, Photo: Archiv Adolf-Luther-Stiftung, Krefeld, Adolf Luther, Hohlspiegelobjekt (silver blue), 1976, mixed media, 61 x 50 cm, , Adolf Luther, Adolf Luther, 1968, mixed media, 45 x 45 cm, , Adolf Luther, Adolf Luther, 1975, mixed media, each 75 cm diameter, ,