Abstract: A lens system comprising, as viewed from the object side, a first positive lens member having its convex surface facing the object side, a second positive lens member having its convex surface facing the object side, a third lens member, and a fourth positive lens member. The distance between the surface of the first lens member which faces the object side and the surface of the third lens member which faces the image side is from 0.4 times to 0.53 times the distance between the surface of the first lens member which faces the object side and the surface of the fourth lens member which faces the image side. The third lens member may comprise a positive lens and a negative lens which are joined together and which satisfy additional conditions.

Abstract: In a single lens reflex camera having a focusing plate, a pentaroof-prism and an eyepiece, an optical system for indicating information within the view field of the finder includes first prism means disposed on the principal optical axis of the finder between the pentaroof-prism and the eyepiece. The incidence surface of the first prism means is parallel to the emergence surface of the pentaroof-prism and the emergence surface of the first prism means forms a predetermined angle .alpha. with a horizontal plane containing the principal optical axis of the finder. A reflector member is disposed at the upper end of the front reflective surface of the pentaroof-prism and outwardly of the boundary point of the finder's view field light. An indicator member is disposed above the first prism means. Second prism means is disposed on the optical axis of the finder between the first prism means and the eyepiece.