Optical sighting instrument with means for producing a sighting mark

An optical instrument comprising a lens means having a concave light reflecting surface serving as a semi-transparent mirror, and a light source for directing light beams to the semi-transparent mirror which is arranged to produce an image of the light source, such that said image to an observer who has his eye directed to the concave mirror surface appears to lie far in front of the mirror to serve as a sighting mark on a sighting line between the observer's eye and a target; the lens means with the semi-transparent concave mirror surface and the light source being arranged such in relation to each other and in relation to the sighting line that the optical main axis from the light source to the lens means intersects the sighting line substantially on the semi-transparent mirror surface and intersects the theoretical optical main axis of the lens means in a point situated close to the focus of the concave mirror surface, and such that the focus and said point are transversely spaced from the sighting line whereby sighting errors as a result of misalignment of the observer's eye in relation to said sighting line will be reduced to a minimum.