The present invention relates to a telescopic sight for a firearm for firing in a downward arc comprising: —a first movable mirror defining a first optical axis, the angle of said first movable mirror being adjustable so as to transmit, during use, the image of a target at an angle of 90°−α with respect to the axis of the barrel of the firearm, α being the desired angle of elevation for a given shot; —an objective lens, on the first optical axis; —a second mirror at 45° with respect to the first optical axis, defining a second optical axis that is parallel to the axis of the barrel of the firearm; —an ocular lens on the optical pathway defined by the mirrors projecting the image of the target to infinity.