A lens arrangement for an optical unit operating in a predetermined spectral range, includes at least two lenses (11-14, 114) of material, which transmits in the spectral range, and a common casing (15), in which the lenses are arranged sequentially. The lenses are at least substantially aligned radially, axially and angularly inclined relative to a common optical axis. Adjacent lenses in the sequence are mounted to allow relative movement therebetween. Abutment faces (2) of the lenses rest against one another. An elastic tensioner (21) pretensions the sequence of lenses in the axial direction. Only one of the lenses (11) in the sequence is axially aligned by way of the common casing. Only a portion of the lenses (11, 114) in the sequence are radially aligned by the common casing; the remaining lenses are aligned with respect to one another by the abutment faces of the respectively adjacent lenses.