An optoelectronic sensor (10) for safe detection of objects (32, 34) of a minimum size in a monitoring area (12), the sensor (10) having an image sensor (16a-b) for acquiring image data of the monitoring area (12) and an evaluation unit (24) configured to detect, in the image data, both finely detected objects (34, 36) with a fine detection capability and coarsely detected objects (32) with a coarse detection capability, the coarse detection capability being coarser than the fine detection capability, and to ignore finely detected objects (36) which are not in a vicinity (38) of a coarsely detected object (32).