A camera has a lens system that includes a lens barrel incorporating therein an image taking lens, the lens barrel being variable in a barrel length between a collapsed state in which the barrel length is relative short and a photographic state in which the barrel length is relative long. The lens barrel comprises a light quantity control member that controls quantity of photographic light passing through the image taking lens, and a light quantity control member saving and advancing mechanism that provides such a control that when the lens barrel changes over from the photographic state to the collapsed state, the light quantity control member is saved from a photographic optical axis, and when the lens barrel changes over from the collapsed state to the photographic state, the light quantity control member is advanced to the photographic optical axis.