Extech hd450 heavy duty data logging light meter with pc interface extech hd 450 p the extech lux meter hd450 is suitable to measure the light in working places offices and public buildings by using the precision silicon photodiode and a spectral filter brings precise measuring data with this equipment p p the hd 450 is both robust and double insulated for the field service in addition the device functions as a data logger that can store up to 16 000 measured values continuously an