A thin viewfinder device includes, in order an object side to a viewing eye side,
a first prism, and a second prism disposed separately from the first prim across
an air gap. The first prism, the air gap and the second prism are arranged in such
a manner that an object light flux obtained within a viewing field passes through
the first prism, the air gap and the second prism so as to reach the viewing eye,
while an object light flux obtained outside the viewing field is totally reflected
by surfaces of the first prism so as to be prevented from reaching the viewing eye.
