The Effect of Lighting and Low Power Magnification on Inspection Performance

Ten subjects tried to identify c's (defects) in a matrix of o's (good items) with five letter sizes, three magnification levels (none, 2***X and 4X) and three illumination levels (1100, 2200 and 4400 lux). Using time as the criterion, when the target gap was larger than 2.S min of arc, no magnification was best; below 2.5, 4X was best. Time was 43.9 s for 1100 lux, 41.2 for 2200 lux and 39.9 for 4400 lux. Using errors as a criterion, no magnification was best for gaps larger than 2.5 min of arc; below 2.5, 4X was best. Illumination had no effect on errors.