A wafer handler comprising: a wafer loading station for loading a wafer mounted on a tacky film; a tensioner for tensioning the tacky film; a picking module for successively picking a plurality of devices from said wafer; a vision system (5, 50) with one or several cameras for capturing a first image of said wafer or of portions of said wafer, said first image comprising a plurality of devices, wherein said vision system is arranged for determining from said first image the individual position of a plurality of devices, and wherein the wafer handle further comprises an additional camera positioned proximate to said picking module and arranged for capturing an second image of a device to be picked, characterised in that the vision system is configured to use the first image to move the wafer in a first movement so that a device to be picked is moved towards a position under the pick-up module, and, to use the second image to move the wafer in a second movement which is finer than said first movement, for fine adjustment of the wafer, so that the device to be picked is centered under the picking module; characterised in that the vision system (5, 50) is further configured to capture an image of the wafer after the picking module has picked one or more devices from the wafer, and wherein the wafer handler further comprises a processor which is configured to, compare the captured image of the wafer to an expected result to identify if all devices, which should have been picked by the picking module from the wafer, have been picked; and determine a number of error made by the picking module based on the comparison between the captured image to an expected result. a wafer loading station for loading a wafer mounted on a tacky film; a tensioner for tensioning the tacky film; a picking module for successively picking a plurality of devices from said wafer; a vision system (5, 50) with one or several cameras for capturing a first image of said wafer or of portions of said wafer, said first image comprising a plurality of devices, wherein said vision system is arranged for determining from said first image the individual position of a plurality of devices, and wherein the wafer handle further comprises an additional camera positioned proximate to said picking module and arranged for capturing an second image of a device to be picked, characterised in that the vision system is configured to use the first image to move the wafer in a first movement so that a device to be picked is moved towards a position under the pick-up module, and, to use the second image to move the wafer in a second movement which is finer than said first movement, for fine adjustment of the wafer, so that the device to be picked is centered under the picking module; characterised in that the vision system (5, 50) is further configured to capture an image of the wafer after the picking module has picked one or more devices from the wafer, and wherein the wafer handler further comprises a processor which is configured to, compare the captured image of the wafer to an expected result to identify if all devices, which should have been picked by the picking module from the wafer, have been picked; and determine a number of error made by the picking module based on the comparison between the captured image to an expected result.