<p>The first lens group (I) has a positive refractive power and comprises a first lens unit (1) consisting of a meniscus lens convexly curved to an object, and a positive refractive power in relation to the object. The second lens unit (2) has a negative refractive power and is fixed to the third lens unit (3) consisting of a biconvex lens with positive refractive power. The fourth lens unit (4) consists of a biconvex lens with positive refractive power. The second lens group (II) has negative refractive power and comprises a fifth lens unit (5) which has a meniscus lens convexly curved towards the picture side and positive refractive power. The sixth lens unit (6) is convexly curved towards the picture side. A seventh lens unit (7) consists of a meniscus lens convexly curved towards the picture side, and possessing a negative refractive power. The image can be magnified or reduced by altering the space between the first and second lens groups.</p>
