The invention describes an observation device, having two tubular observation parts, wherein the longitudinal axes of the observation parts in the region of the ocular sides are spaced apart by a distance of at least 54 mm. At least one observation part has a flared portion on an external side, wherein the flared portion is located inside a subsection of between 20% and 80% of an overall length of the observation part. The flared portion lies in an annulus section having a normal distance to the optical axis of the objective of between 130% and 250% of the radius the objective lens.