A crane comprising: a carrier unit; a superstructure mounted on the carrier unit, the superstructure including a boom having a boom nose; a cable extending from the free end of the boom; a lifting appliance coupled to the cable and suspended from the boom; and an optical detection system comprising: an image capture device positioned to have a field of view in which the lifting appliance is disposed, and configured to capture an image; and an optical detection computer comprising a processor and a computer-readable storage medium, wherein the optical detection computer is configured to: detect one or more objects in the captured image, the one or more objects selected from: the lifting appliance, the cable, a load coupled to the lifting appliance, an object remote from the crane and a marker; analyze the one or more detected objects; and determine a condition of a crane component based on the analysis of the one or more detected objects, wherein a detected object of the one or more detected objects is the lifting appliance; characterized in that the lifting appliance is analyzed to determine a distance between the lifting appliance and the boom nose, wherein the determined condition of the crane component includes one or more of a two-block condition, an absence of a two-block condition, an approaching two-block condition, and the condition is determined based on a comparison of the determined distance between the lifting appliance and the boom nose and a threshold distance stored in the computer readable storage medium. a carrier unit; a superstructure mounted on the carrier unit, the superstructure including a boom having a boom nose; a cable extending from the free end of the boom; a lifting appliance coupled to the cable and suspended from the boom; and an optical detection system comprising: an image capture device positioned to have a field of view in which the lifting appliance is disposed, and configured to capture an image; and an optical detection computer comprising a processor and a computer-readable storage medium, wherein the optical detection computer is configured to: detect one or more objects in the captured image, the one or more objects selected from: the lifting appliance, the cable, a load coupled to the lifting appliance, an object remote from the crane and a marker; analyze the one or more detected objects; and determine a condition of a crane component based on the analysis of the one or more detected objects, wherein a detected object of the one or more detected objects is the lifting appliance; characterized in that the lifting appliance is analyzed to determine a distance between the lifting appliance and the boom nose, wherein the determined condition of the crane component includes one or more of a two-block condition, an absence of a two-block condition, an approaching two-block condition, and the condition is determined based on a comparison of the determined distance between the lifting appliance and the boom nose and a threshold distance stored in the computer readable storage medium. an image capture device positioned to have a field of view in which the lifting appliance is disposed, and configured to capture an image; and an optical detection computer comprising a processor and a computer-readable storage medium, wherein the optical detection computer is configured to: detect one or more objects in the captured image, the one or more objects selected from: the lifting appliance, the cable, a load coupled to the lifting appliance, an object remote from the crane and a marker; analyze the one or more detected objects; and determine a condition of a crane component based on the analysis of the one or more detected objects, wherein a detected object of the one or more detected objects is detect one or more objects in the captured image, the one or more objects selected from: the lifting appliance, the cable, a load coupled to the lifting appliance, an object remote from the crane and a marker; analyze the one or more detected objects; and determine a condition of a crane component based on the analysis of the one or more detected objects, wherein a detected object of the one or more detected objects is the lifting appliance; characterized in that the lifting appliance is analyzed to determine a distance between the lifting appliance and the boom nose, wherein the determined condition of the crane component includes one or more of a two-block condition, an absence of a two-block condition, an approaching two-block condition, and the condition is determined based on a comparison of the determined distance between the lifting appliance and the boom nose and a threshold distance stored in the computer readable storage medium.