For satisfactory vision the minimium illumination accepted is -
An illumination of 15 to 20 foot-candles is accepted as a minimum basic requirement for satisfactory vision. 1 FC = 10.76 Lux Park's Textbook of Preventive and Social Medicine, 25th Edition, Pg 799
15 to 20 foot candles
30 to 40 candles
40 to 50 candles
70 to 90 candles
Environment and health