Abstract: An eyepiece for use in a viewfinder optical system has a wide dioptric power adjustment range. The eyepiece is provided with, from a side of a secondary-image plane formed by a first, a second, and a third relay lens, a first, a second, and a third eyepiece lens having a positive, a negative, and a positive refractive power, respectively. For dioptric power adjustment, the positive first eyepiece lens or the negative second eyepiece lens is moved in an optical axis direction.

Abstract: An objective lens system particularly adapted for photography with a frontal aperture stop is provided. The lens system includes four lens components including a positive doublet. A diaphragm is provided in front of the first lens component and the lens system satisfies the following relationships;1.84 > N.sub.1 > 1.6 (1) 65 > V.sub.1 > 44 (2)0.7 > d.sub.1 + d.sub.2 /.SIGMA.d > 0.3 (3) 1.5 > .vertline.R.sub.3 .vertline./R.sub.4 > 0.5 (4)0.25 > .vertline.n.sub.3 - n.sub.4 .vertline. > 0.03 (5) 25 > .vertline.V.sub.3 - V.sub.4 .vertline. > 5 (6)0.0005 > n.sub.4 - n.sub.3 /r.sub.6 < 0.0035 (7) 1.0 > R.sub.5 /R.sub.7 > 3.0 (8)wherein, N, is the index of refraction, V is the Abbe number, D are axial distances along the optical axis and R is the radii of curvature. The subnumbers refer to consecutive measurements along the optical axis.